6
Name ______________________________
Period ________
Intro to Chemistry: Atoms & the Periodic Table Accelerated Science 8 Page
Assignment Title Mercury: Mysterious and Deadly Article & Homework Questions Notes: Introduction to the Modern Atom Identifying Sub-atomic Particles of an Atom Evolution of Atomic Theory Periodic Table Scavenger Hunt Notes: Periodic Table of the Elements Notes: Lewis Dot Structures Lewis Dot Structures Notes: Bohr Model Diagrams Simple Bohr Model Diagrams Notes: Physical & Chemical Properties of Elements Identifying Physical vs. Chemical Properties Physical Properties of the Elements Lab Notes: Ions, Acids, and Bases pH Lab: Acids vs. Bases
2-3 4 5-6 7-8 9 10 11 12-13 14 15-16 17 18 19-23 24 25-28
Type of Assignment
Date Due
Grade Received
Article/EDMODO notes EDMODO notes/EDMODO activity notes notes HOMEWORK notes HOMEWORK notes EDMODO LAB/EDMODO notes LAB/EDMODO
Atoms: 5.1 5.2 5.3 5.4
TSW explain that matter is composed of tiny particles called atoms. TSW describe the characteristics of protons, neutrons, and electrons based on their relative mass, charge, and location in the atom. TSW develop an operational description of the atomic theory. TSW explain that atomic theories have changed over time.
The Periodic Table: 5.6 5.7 5.8 5.9 5.10 5.11 5.12
TSW recognize that within a period on the periodic table, the atomic number of elements increase by one proton going from left to right. TSW recognize that groups on the periodic table contain elements with similar properties. TSW use the periodic table to find the symbols for elements. TSW recognize the symbols for carbon, oxygen, hydrogen, sodium, and chlorine. TSW relate the structures (# of protons) and properties of atoms to their positions in the periodic table. TSW use the periodic table to classify elements as metals or non-metals. TSW recognize the periodic table as a tool for organizing information.
Describing Elements & their Properties: 6.1 6.3 6.14 6.15 6.18
TSW explain that elements combine to form all known living and non-living substances. TSW explain that atoms and molecules are in constant motion. TSW demonstrate the properties that can be used to identify matter: density, acidity, and magnetism. TSW calculate density using a variety of solids. TSW accurately measure and describe mass, volume, and density. 1
Mercury: Mysterious and Deadly Excerpt reprinted with permission from “The Genie in a Bottle,” by Dr. Joe Schwartz Not long ago, I traced down some research papers authored by Karen Wetterhahn, and I was amazed by their diversity. Wetterhahn, the first female professor of chemistry ever hired at Dartmouth, was interested in fields ranging from biochemistry to toxicology. She was an expert on the cancer-causing potential of chromium, and, like numerous chemists before her, she was fascinated with the chemistry of mercury and its compounds. The Ancient Greeks were well aware of the properties of this liquid metal. They could make a glob of it scatter into tiny droplets so quickly (hence the term “quicksilver”) that they named it after Mercury, the fleet messenger of the gods. The Chinese were also intrigued by the appearance of mercury, and thought that it held the key to longevity and perhaps even immortality. They were wrong. In fact, the Romans had already noted that the men who mined cinnabar (mercuric sulfide), the naturally occurring ore from which mercury is extracted, had a short life expectancy. Accordingly, the sent only the worst criminals off to toil in the quicksilver mines of Spain. Some of these men would suffer from tremors, excessive salivation, fits of hostility and memory loss. Indeed, the outward beauty of mercury belies its extreme toxicity. The alchemists of the Middle Ages learned about this the hard way. They believed that all metals were mixtures of mercury and other substances, and they struggled to combine mercury with sulfur to make gold. Instead of wealth, they acquired mercury poisoning. The great Isaac Newton may well have been among them. Most people connect Newton with falling apples, but the man also dabbled in alchemy. In his notebooks,
he recorded numerous mercury experiments and described his concoctions as being “sweetish,” “saltish,” and “vitriolic.” He obviously tasted his products, so we should not be too surprised that in 1692 he started to betray signs of mental illness. Newton suffered delusions, periods of melancholy, sleeplessness, and loss of appetite – all typical symptoms of mercury poisoning. When Newton left his laboratory to become Master of the Mint in London, the symptoms disappeared and his brilliance returned. But not everyone exposed to mercury was so lucky. Some were driven mad by the lustrous metal. Hatters, for example. Lewis Carroll’s fictional Mad Hatter could well have been based upon some real people. In those days, the felt used for hat-making was made from rabbit, hare, or beaver fur, which the hatter would mat by treating it with hot mercuric nitrate. Erratic behavior, along with swollen gums and tremors, became the recognized consequences of hatting. Today we no longer tinker with alchemy, and mercury has long been abandoned by hat manufacturers. But this doesn’t mean that we don’t still have to contend with mercury exposure. The chemical industry employs the metal as a catalyst, and mercury is an integral part of the process used to produce chlorine and lye (sodium hydroxide) from salt. It is also found in electrical switches, dental amalgams, batteries, detonators, and, of course, thermometers. One would not think that a shiny little sliver of mercury sealed in a thermometer could cause problems, but broken thermometers have resulting in a number of hospitalizations. Children are especially susceptible to the effects of mercury vapor, because of their 2
small size. The symptoms they experience may include loss of appetite, drooling, excessive perspiration, listlessness, itchiness, and swollen, reddish, cold extremities. Rapid heartbeat and elevated blood pressure may also occur. Unfortunately, mercury poisoning is not always the first thing that comes to a physician’s mind when he or she is confronted with such symptoms. A proper diagnosis may take some time. Clearly, prevention is
the best protection. We should clean up a mercury spill immediately. Vacuuming is generally not the best cleaning method, because a vacuum cleaner will separate the mercury into tiny droplets and spread them throughout the air via the exhaust; but if the spill is on the carpet, there is really no alternative. Remove the used bag from the vacuum cleaner right away, place it in a plastic bag, and discard it as toxic waste. Most municipalities have special arrangements for disposing of such waste.
Mercury: Mysterious and Deadly Homework Questions (10 pts)
1. Justify what makes each of the elements unique. ______________________________________________________________ 2. How did Mercury get the nickname “quicksilver?” ______________________________________________________________ 3. The Chinese were intrigued by Mercury’s appearance and properties. However, what was one misconception they had about its ability to do? __________________________________________________________________________________ 4. What is “Alchemy?” __________________________________________________________________________________ 5. Why did alchemists struggle to make Gold using other elements? __________________________________________________________________________________ 6. Many people over time were found to have health problems (including Sir Isaac Newton!). What was eventually found to be the cause of it? __________________________________________________________________________________ 7. What are some of the side-effects of Mercury exposure? __________________________________________________________________________________ 8. Why would thermometers now contain alcohol (with red dye) rather than the element Mercury (silver in color)? __________________________________________________________________________________ 9. Why should you NOT vacuum up a Mercury spill? How should you clean it instead? __________________________________________________________________________________ 10. What does this article have to do with the Chemistry? __________________________________________________________________________________ 3
Notes: Intro to the Modern Atom 5.1 - TSW EXPLAIN THAT MATTER IS COMPOSED OF TINY PARTICLES CALLED ATOMS. Chemistry is the science of ____________________ dealing with the composition of substances, their ____________________, and how they _____________________ with other substances An atom is the smallest part of an _________________ that can be broken down, and still have the characteristics of that __________________ o ______ _______________ in the universe are made up of atoms o Atoms of the same element are _____________________ to one another o Atoms of different elements are made up of __________________ atoms 5.2 - TSW DESCRIBE THE CHARACTERISITICS OF PROTONS, NEUTRONS, AND ELECTRONS BASED ON THEIR RELATIVE MASS, CHARGE, AND LOCATION IN THE ATOM.
Sub-Atomic Particles All atoms are made up of __________ smaller pieces called “sub-atomic particles” A PROTON is a _________________ charged sub-atomic particle o Located in the center (______________ ) of the atom o They have a mass of ___________ (“amu” = “atomic mass unit”) o The number of _____________ in an atom is what gives each atom its different _______________ o RULE #1: The ______________ ________________ of an atom is determined by looking at the number of ____________ in an atom A NEUTRON is a _____________________ charged sub-atomic particle o Located in the ________________ of the atom o They have a mass of _______________ (Same size as the __________________) The NUCLEUS of an atom is the ________________ part of an atom o RULE #2: The _____________ ______________ of an atom is found by adding the # of _______________ to the # of ___________________ o The nucleus is ___________________ charged (Takes on the charge of the (+)_________________, NOT the (0)_________________) o The most __________________ part of the atom The ELECTRONS are _______________ charged particles that are found in the _______________ ____________ o Located in __________________ that spin around the nucleus o Are ________________th the size of a proton or neutron o RULE #3: As a general rule, the number of _____________ is usually equal to the number of ___________, making the atom have an overall ______________ charge. o Electrons revolve around ___________ in imaginary paths called ________ or ________ o VALENCE ELECTRONS are electrons that orbit the atom in the __________________ ________________, and are responsible for ____________________ with other atoms 4
Identifying Sub-Atomic Particles in an Atom Each element is made up of just one type of atom, but every atom, regardless of the element it makes up, is made up of even smaller units called sub-atomic particles. In this worksheet, you will practice finding the number of each of the types of sub-atomic particles, and see how similar – yet how different – each atom is to one another!
Part One: Background Knowledge
An atom is the… _____________________________________________________________________ ___________________________________________________________________________________
_____________________________________ is made up of atoms.
Atoms of the same element are ____________________________.
Atoms of different elements are ____________________________.
All atoms are made up of _________________________________________________.
Fill out the parts of the atom based on the information you have filled out in the table above.
Complete the following chart based on the information we have discussed in class. Mass
Charge of Sub-Atomic Particle
Location Within the Atom
Sub-Atomic Particle Yes
No
Positive (+)
Negative (-)
Neutral (0)
Inside Nucleus
In Electron Cloud
Proton Electron Neutron Nucleus
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Fill out the information below based on the rules we discussed in class. 1. Rule #1: The Atomic Number of an atom is determined by looking at the number of ______________. 2. Rule #2: The Atomic Mass of an atom is found by adding the number of ____________________ to the number of ________________. 3. Rule #3: As a general rule, the number of ___________________ is usually equal to the number of __________________, making the atom have an overall neutral charge.
Part Two: Identifying Sub-Atomic Particles Use the Periodic Table, and the information from Part One to help you fill in the blanks in the table below.
Element
Symbol
1. Hydrogen 2. Helium
# of Protons
# of Electrons
1 He
3. Lithium
2
6
1
N
6
7
14 8
7. Potassium
19
19
P
15
9. Aluminum
14
11. Calcium
20
13
29
35
79 Ag
31
13 26
56
11
23
12
24
29
14. Magnesium 15. Gold
19
20
12. Sodium Cu
16
15
10. Iron
16.
1
7
8
13.
Atomic Mass
2
6. Oxygen
8.
Atomic Number
3
4. Carbon 5.
# of Neutrons
197 61
47
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Evolution of the Atomic Theory Scientist:
Democritus
Diagram of Model:
Year of Theory: Name of Model: Experiments/Observations:
Discovery: Description of Model:
Scientist:
John Dalton
Diagram of Model:
Year of Theory: Name of Theory: Name of Model: Experiments/Observations:
Discovery: Description of Model:
Scientist:
J.J. Thomson
Diagram of Model:
Year of Discovery: Name of Model: Experiments/Observations:
Description of Model: Discovery:
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Scientist:
Ernest Rutherford
Diagram of Model:
Year of Discovery: Name of Experiment: Name of Model: Experiments/Observations:
Description of Model: Discovery:
Scientist:
Niels Bohr
Diagram of Model:
Year of Discovery: Name of Model: Experiments/Observations:
Description of Model: Discovery:
Louis de Broglie & Erwin Schrodinger Scientist:
Diagram of Model:
Year of Discovery: Name of Model(s): Experiments/Observations:
Description of Model: Discovery:
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Periodic Table Scavenger Hunt
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Notes: Periodic Table of the Elements 1.3 – THE STUDENT WILL DESCRIBE HOW SCIENTIFIC KNOWLEDGE HAS BEEN REVISED BASED ON EVIDENCE. Element (def.) – A substance that is made up of one kind of ____________ o Cannot be broken down by ____________ or ____________ means All listed in the __________ ____________: ~____ natural; ~____ synthetic (artificial) Organizing the Elements: Arrangement of the Periodic Table Thales (600 B.C.) – Believed _______________ was one of the original “elements” Xenophanes (500 B.C.) – Added _______________ to the things that made up the world around him Empedocles (440 B.C.) – Developed the idea of ____________ elements: ________________, __________________, ___________________, ________________ Democritus (400 B.C.) – Hypothesized the existence of a smaller particle that made up the four “_____________” in the world around him o Since “______________” is Greek for “indivisible,” Democritus called these particles “____________” Robert Boyle (1661) – Redefined elements to mean what we know now: o An ________________ is a substance that cannot be broken down by __________________ or __________________ means o Defined by ________________________, NOT theory o Scientists grouped elements with similar ___________________ into what they called “____________” or “____________________” Johann Wolfgang Dobereiner (1829) – Grouped known elements into __________________ of triads of elements with similar __________________ John Newlands (1865) – Ordered the elements by increasing __________________ o Grouped the elements into ________________ vs. ____________________ o Noticed every ____________ element was similar to the one that came next Mendeleev (1869) – Grouped the 63 known elements at that time based on their similar _________________ __________________________ o Arranged elements in order of increasing _________________ ______________ o He also left some spaces blank so that new elements could be added where he predicted they’d occur o He also predicted the ____________________ and ___________________ properties for undiscovered elements, which allowed for his theories to be tested Henry Moseley (1913) – Reordered the elements based on their increasing _________________ ____________ 5.6 - TSW RECOGNIZE THAT WITHIN A PERIOD ON THE PERIODIC TABLE, THE ATOMIC NUMBER OF ELEMENTS INCREASE BY ONE PROTON GOING FROM LEFT TO RIGHT. 5.7 - TSW RECOGNIZE THAT GROUPS ON THE PERIODIC TABLE CONTAIN ELEMENTS WITH SIMILAR PROPERTIES. Modern Periodic Table The Period Law: The ____________________ and ____________________ properties of an element is directly related to its __________________ ______________________ o An element’s properties can be ________________ from its __________________ in the periodic table!
(NOTES FOR THE PERIODIC TABLE CONTINUE ON STUDENT COPY OF THE PERIODIC TABLE) 10
Notes: Lewis Dot Structures Review: The Electron Cloud o Surrounds the ________________________ o ______________________ charged region of space Made up of mostly ___________________ __________________ Probable region where __________________ may be found o Electrons orbit the nucleus in ____________________ ____________________ The Valence Electron Shell is the ______________________ level in which electrons orbit the nucleus o Valence Electrons determine how the atom will ___________________ with other atoms o Represented by ____________ o Group A Elements follow a pattern when identifying the number of valence electrons Group 1 (IA) has ___________ Valence Electron Group 2 (IIA) has ___________ Valence Electrons Group 13 (IIIA) has ___________ Valence Electrons Group 14 (IVA) has ___________ Valence Electrons Group 15 (VA) has ___________ Valence Electrons Group VIA has ___________ Valence Electron Group VIIA has ___________ Valence Electrons Group VIIIA has ___________ Valence Electrons Lewis Dot Structures (Electron Dot Diagrams) – One way to visually represent the number of __________________ __________________ in an atom o Made up of a ___________________ (surrounded by)… o The number of _______________ _____________________ Rules for Drawing Lewis Dot Diagrams: The ________________ _________________ is drawn in the center ________________ _________________ are added beginning on the right hand side of the symbol, and then continue counter-clockwise to the symbol, one dot at a time Once each dot has a pair, that side is _______________ The maximum number of valence electrons is ____________ Group 1 # of V.e’ = ______
Group 2 # of V.e’ = ______
Group 13 # of V.e’ = ______
Group 14 # of V.e’ = ______
Group 15 # of V.e’ = ______
Group 16 # of V.e’ = ______
Group 17 # of V.e’ = ______
Group 18 # of V.e’ = ______
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Lewis Dot Structures Uses of Lewis Dot Structures in Chemistry: 1. Determine the type of covalent bonds (sharing) that an element may form 2. Predict the type of ionic bond (transfer) that an atom might make when it forms an ion
Each dot diagram consists of: 1. Kernel - the element symbol in the center 2. Valence Electrons - the outermost electron shell of the atom; represented by a group of 1-8 dots
Organization of a Lewis Dot Structure: 1. Each "side" of the symbol represents an orbital in the outermost energy level of the atom. 2. Each orbital can hold only two electrons, so the sides of the dot diagram can only hold two dots 3. Place the first two dots on the right side, but the rest of the dots should be placed in a counterclockwise manner, with no side receiving two dots until each side gets one.
Group
# of Valence Electrons
1 (IA) 2 (IIA) 13 (IIIA) 14 (IVA) 15 (VA) 16 (VIA) 17 (VIIA) 18 (VIIIA)
Example: Phosphorus Group: 15 # of Valence Electrons: 5
Below are examples for how to fill in the dots on dot diagrams for elements with 1-8 valence electrons.
Write the group number, and number of valence electrons for each element. Then draw the Lewis Dot Structure for each.
Step One
Step Two
Step Three
Step Four
X
X
X
X
Step Five
Step Six
Step Seven
Step Eight
X
X
X
X
Practice Problems: Aluminum Symbol: ______ Group #: ______ # of Valence e-: _____
Krypton Symbol: ______ Group #: ______ # of Valence e-: _____
Iodine Symbol: ______ Group #: ______ # of Valence e-: _____
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Homework Problems: Arsenic
Barium
Symbol: ______ Group #: ______ # of Valence e-: _____
Symbol: ______ Group #: ______ # of Valence e-: _____
Xenon
Lead
Symbol: ______ Group #: ______ # of Valence e-: _____
Symbol: ______ Group #: ______ # of Valence e-: _____
Sodium Symbol: ______ Group #: ______ # of Valence e-: _____
Carbon Symbol: ______ Group #: ______ # of Valence e-: _____
Oxygen Symbol: ______ Group #: ______ # of Valence e-: _____
Hydrogen Symbol: ______ Group #: ______ # of Valence e-: _____
Sulfur Symbol: ______ Group #: ______ # of Valence e-: _____
Lithium Symbol: ______ Group #: ______ # of Valence e-: _____
Chlorine Symbol: ______ Group #: ______ # of Valence e-: _____
Nitrogen Symbol: ______ Group #: ______ # of Valence e-: _____
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Notes: Bohr Models Drawing a Bohr Model is another way to represent what an ________________ looks like Bohr Model diagrams show: o The number of ________________ and ___________________ in the nucleus o The number of ___________________ (from the ____________________ the atom is located in) o The number of __________________ in each ______________________ Bohr Models represent: o The nucleus will show the number of ___________________ and _________________ Can be shown using the exact amount of __________________ to represent each Can be represented by __________________ of each o Electrons are drawn as ______________ in each orbital o Each orbital can only fit a certain number of electrons: After the first shell becomes full, it “grows” another orbital, and begins to fill that shell as well! Orbital 1: _______ electrons Orbital 2: _______ electrons Orbitals 3: _______ electrons Orbitals 4-6: _______ electrons [Valence Shell: _______ electrons] NOTE: Transition metals will often start filling a new shell, even if their current shell is not full! Here is another reason they are considered “B” (bad) elements! Drawing Bohr Models o Step 1: Identify the __________ you wish to draw! o Step 2: Draw a ______________ to represent your nucleus o Step 3: Using the Atomic Number, determine the number of ____________ in the nucleus, and record inside the circle o Step 4: Using the Atomic Mass, calculate the number of _______________ in the nucleus and record inside the circle o Step 5: Identify the number of _______________ in the atom (*Hint: Find the Period that the atom exists in!) o Step 6: Draw _____________ around the nucleus to represent the number of orbitals o Step 7: Using the number of protons, determine the total number of __________________ o Step 8: Fill in the Orbitals with the correct number of ________________ Level 1: Can only hold ________ electrons Level 2: Up to ________ electrons Level 3: Up to ________ electrons Level 4-6: Up to ________ electrons Valence Shell: Can hold up to ________ electrons o Step 9: Double check your work!
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Simple Bohr Model Diagrams
How many electrons fit in each shell?
1st shell = 2 2nd shell = 8 3rd shell = 18 4th shell = 32 nth shell = 2n2
For each element, check the Periodic Table to find out how many electrons each element actually has and write the total number of electrons on the line. Then, color/draw in the correct number of electrons for each orbit. Remember, fill the orbit closest to the nucleus first, but never exceed the number each orbit can hold. Practice Problems: Color in the correct number of valence electrons found in each shell. Phosphorous (P) ______
Silicon (Si) ______
Oxygen (O) ______
Chlorine (Cl) ______
Argon (Ar) ______
Magnesium (Mg) ______
Practice Problems: Practice drawing the correct number/placement of valence electrons found in
each shell.
Helium (He) ______ P = _______, N = ________
Carbon (C) ______ P = _______, N = ________
Potassium (K) ______ P = _______, N = ________
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Silicon (Si) ______
Calcium (Ca) ______
Oxygen (O) ______
Sodium (Na) ______
Magnesium (Mg) ______
Argon (Ar) ______
Bohr Model Diagrams Use the information provided to draw Bohr Model diagrams for each of the elements listed. Draw the individual electrons on the appropriate energy levels (keep in mind the maximum number of electrons allowed on each level).
Beryllium Atomic #: 4; Atomic Mass: 9
Sulfur Atomic #: 16, Atomic Mass: 32
Fluorine Atomic #: 9, Atomic Mass: 19
Nitrogen Atomic #: 7; Atomic Mass: 14
Aluminum Atomic #: 13, Atomic Mass: 27
Boron Atomic #: 5; Atomic Mass: 11
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Notes: Physical Properties of Elements Physical Property is a ____________________________ of an object’s appearance, or an __________________ that can be made WITHOUT changing the object at the _____________________ ____________________ o They are observed using the ______________________ (Ex: ___________________, __________________, ____________________) o Used to observe and ___________________ matter What it is (Ex: _____________________________________________) What it looks like (Ex: _____________________________________________) What it can do (Ex: _____________________________________________) TRUE / FALSE. The substance is changed when you observe a physical property Words to Describe Physical Properties Color
Magnetic (def.) –
Luster (def.) –
Paramagnetic- __________ to magnets
Odor (def.) –
Diamagnetic- __________ by magnets
State of Matter (def.) –
Malleable(def.) –
Texture (def.) –
Ductile (def.) –
Mass (def.) –
Freezing Point (def.) –
Volume (def.) –
Melting Point (def.) –
Density (def.) –
Boiling Point (def.) -
Formula: Buoyancy (def.) –
Solubility (def.) – Conductivity (def.) –
Chemical property describes how a substance ______________ with something else o When you observe a chemical property, you end up _____________________ the substance and its __________________ o You ___________________ get the substance back Ex: The ability of iron to rust after it has reacted with oxygen, heat of combustion, reactivity with water, pH Qualitative Observation – one that can be measured with the _________________________ o Is _______________ precise o Ex: _________________________________________ Quantitative Observation – one that involves ________________________ the quantity or amount of something o It ________ precise o Ex: _________________________________________
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Identifying Physical vs. Chemical Properties Accelerated Science 8 A physical property is something that is observed with the senses and can be observed without destroying the object. For example, an object’s appearance such as its shape and length, are examples of physical properties. A chemical property, however, is something that is observed only when an object is fundamentally changed by a chemical reaction. For example, the ability of iron to rust is a chemical property. The iron has reacted with oxygen, and the original iron metal has changed into iron oxide, a completely different substance. Part One: Classifying Physical or Chemical Properties
Complete the chart below. Define each of the terms, and identify if they represent a physical or chemical property, using a “P” for a Physical Property, and a “C” for a Chemical Property.
Property of Substance
Definition or Description of Property
Identify Property as Physical (P) or Chemical (C)
1. Ability to rust 2. Boiling Point 3. Buoyancy 4. Color 5. Conductivity 6. Density 7. Ductility 8. Elasticity 9. Flammability 10. Hardness 11. Luster 12. Magnetism 13. Mass 14. Malleability 15. Melting Point 16. Odor 17. Reactivity with acid 18. State of Matter 19. Texture 20. Volume
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Physical Properties of Elements Lab Accelerated Science 8 Objectives: Explain that some properties can be used to describe substances, and that some can be used to identify substances. (6.12) Classify substances using their properties. (6.13) Background Knowledge: A physical property of an object is what can be measured or perceived about that substance, without changing the object itself. In this lab, we will spend time looking at some of the physical properties of various elements found within the walls of our own classroom. Use the vocabulary terms discussed in class to describe each of the properties below. Be sure to read and follow all directions! Elements to Observe: 1 Aluminum strip 1 Copper strip 1 Iron strip 1 Lead strip
1 Nickel coin & Nickel strip 1 bag filled with “Nitrogen”(*Please keep inside the plastic bag ) 1 Tin strip 1 Zinc strip
Lab Part 1: Physical Properties from the Senses Often physical properties are only described using the five senses you possess. Work with your partner to fill out the chart below. You will only use your senses of sight, smell and touch. 1. Record the atomic symbol for each of the elements you are observing today. 2. For each state of matter, label each element as being a solid, a liquid or a gas. 3. For the texture, look at each object underneath the hand lens. Does your element have a smooth texture or is the surface rough and pitted? 4. Look at each of the elements in front of you. Describe the color for each of the objects, being as descriptive as you can. (Ex: Dull yellow, dark gray, light silver, etc.) 5. Test the element’s luster by looking at its surface. If the element has luster, it will appear shiny. You may need to scrape or rub the element’s surface with your finger to get the luster to appear. If the element does not “shine,” it may be said to have a dull appearance.
6. Next, sniff each of the objects. What odor does each element possess? Often, if something smells “good,” the odor is said to be pleasant, while things that have a “bad” smell are unpleasant. If an object has a distinct, specific odor, such as a metallic smell, try to describe it.
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Data Table 1: Physical Properties from the Senses (24 pts) Aluminum
Copper
Iron
Lead
Nickel
Nitrogen
Tin
Zinc
Atomic Symbol State of Matter Texture Smooth or Rough
Color
Luster Shiny or Dull Odor Pleasant or Unpleasant
N/A (Don’t open the bag)
Lab Part 1: Conclusion Questions (6 pts)
1. Were any of the elements you observed today changed on a molecular level as you checked their physical properties? How can you tell? (2 pts) _______________________________________________________________________________________ _______________________________________________________________________________________
2. Which of the elements you observed today had luster? What does luster mean in terms of how light reflects off of the surface of the element? (2 pts) _______________________________________________________________________________________ _______________________________________________________________________________________
3. Which properties did the majority of elements have in common? Based on what you know about the Periodic Table, why do you think this is? (2 pts) ______________________________________________________________________________________ ______________________________________________________________________________________
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Lab Part 2: Physical Properties through Measurements For this part of the lab, you and your partner will need to go beyond simply what you can see, smell or touch. You will test the elements for different physical properties they possess that must be measured or tested. Through each observation, the elements will remain the same, even if their shape changes. As you complete this portion of the lab, be thinking about ways the elements are grouped on the Periodic Table of Elements and how they correspond to the properties you discover. Materials: (1 per group) (Same element samples from Part 1) Periodic Table of Elements Triple-beam balance Metric Ruler 1 Circular Magnet 1 Pie Tin 250mL Beaker of Water Procedures: 1. Use your triple beam balance to find the mass of each element sample. Record your measurement in grams (g). 2. Use a metric ruler to find the volume of each element sample. Record your measurement in cubic centimeters (cm3). *NOTE: You may need to find the thickness of each sample in millimeters, and then convert your answer into centimeters. 3. Determine the density of each element by dividing the mass by the volume. Record your answer in g/cm3. 4. Use a magnet to test each of the samples to see if they possess magnetic properties. Do any of the objects attract or repel the magnet? If the sample does not react when touched with the magnet, simply write, “no.” 5. Using your hands, GENTLY try to bend each of the objects. Another name for the flexibility of an object is its “malleability.” Objects that are flexible (malleable) are easy to bend. Those that are not are usually said to be non-malleable. 6. Test each element’s buoyancy by placing it into a shallow pan of water. Does the sample sink or float? Objects that are less dense than water will float when placed in a pan of water, and are said to be “Buoyant.” Objects that are denser than water will sink, and are considered “Not Buoyant.” 7. Using the observations you have made so far, as well as your Periodic Table, classify each element as being a Metal, Non-Metal, or Metalloid.
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Data Table 2: Physical Properties through Measurements (24 pts) Aluminum
Copper
Iron
Lead
Nickel
Nitrogen
Tin
Zinc
Mass (g)
Volume (cm3)
Density Mass ÷ Volume (g/cm3)
Magnetism Yes or No
Malleable Yes or No
Buoyancy Buoyant or Not Buoyant
Classification Metal, Non-Metal or Metalloid
Check for Understanding: (6 pts) 1. An object with low luster should look ____________, and one with high luster should look __________. 2. An object that is buoyant is able to _____________________________________________. 3. An object that is not malleable cannot _______________________________________________. 4. What tool do you use to test if the metals had magnetic properties? ___________________ 5. Calculate the density of an object with a mass of 120g and a volume of 7cm3? SHOW YOUR WORK. ______________ 22
Lab Part 2: Conclusion Questions (6 pts) 1. The strip of pure nickel is MAGNETIC / NOT MAGNETIC, while the U.S. nickel coin you tested is MAGNETIC / NOT MAGNETIC. Why do you think there might be a difference between these samples? (3 pts) __________________________________________________________________________________ __________________________________________________________________________________ 2. Some objects that are malleable are also found to be ductile. This means that they can be stretched or pulled into a cord, most often to be used in piping or electrical cords. Which of the malleable objects that you tested might be ductile as well? Explain your logic. (2 pts) _________________________________________________________________________________ __________________________________________________________________________________ 3. You are cleaning up at the end of class and find one of the strips of metal from the lab on the floor. The symbol has rubbed off, but you know that you can identify this substance using the observations you have made in class so far. After making a few observations, you see that the element is: Solid Dull Not magnetic Dark gray Malleable Density of Rough Not buoyant 11.3 g/cm3 The element you have found is: _____________________ (1 pt)
Extra Credit Extensions: 1. Observe the physical properties for other element samples in the classroom. Create a data table to organize your information. Relate the physical properties you observe to the elements’ location on the Periodic Table. (Max 8 points extra credit) 2. Explore the properties and purposes of various elements within breakfast foods. Elements like Iron, Zinc, Magnesium, and Phosphorous are commonly found in breakfast cereals. Explore the physical properties of these elements and find out why we would need them as a part of a healthy diet. (Max 10 points extra credit) 3. Discover the elements found in common objects around your house. Look in your shampoo, dish soap, laundry detergent, cooking spray, etc., and record the compounds with the names of elements you recognize. (i.e. – Body Lotion from Bath & Body Works includes a compound called “Sodium Hydroxide,” or lye!) Using what about what you know about these elements and information you find online, explore how or why the element is in this substance. (Max 5 points extra credit) 4. Create your own extension to further explore physical properties of common elements. (Extra credit points will be awarded based on the complexity and depth of assignment.)
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Notes: Ions, Acids, and Bases Ion (def.) – an atom that has _________________ or _________________ electron(s) o Why? Because every atom wants __________ electrons in their ________________ _______________ An atom with more electrons than protons – it has a more ____________________ charge An atom with more protons than electrons – it has a more ____________________ charge So to become neutral… the atoms must either _____________ or _____________ electrons so that the charges balance out! Anion – atoms that ____________ electrons to become more _____________________ charged o Anions are ___________________ charged, because they have more electrons than protons Ex: Chlorine (Cl) can be an anion because it easily gains an electron to become stable as Cl Ex. Element X as an anion: X Cation – atoms that ____________ electrons to become more _____________________ charged o Cations are __________________ charged, because they have more protons than electrons Ex: Hydrogen (H) can be a cation because it easily loses its one valence electron to become H+ Ex. Element X as a cation: X+
Property Definition: When added to water, it produces… The strength is based on the concentration of… (The higher the concentration, the stronger the substance!) Corrosive to skin & tissues? (Yes or No) Tastes… Can neutralize… Can dissolve… Turns litmus paper… Has a pH value… Feels like… Examples:
Acid
pH Scale (def.) 0 - 6.9 = _______________ 7 = ___________________ Litmus paper (def.) – Acids - turn litmus paper a shade of __________________ Bases - turn the paper a shade of __________________
Base (Alkalines)
7.1 - 14 = ________________
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pH Lab: Acids vs. Bases Accelerated Science 8 Objectives: After completing this lab, you will be able to Identify acids and bases using pH (litmus) paper Interpret degrees of color change in litmus paper Compare the strengths of various household acids and bases
Background Knowledge: The arrangement of elements on the periodic table is one of the most important advancements in chemistry throughout the past few hundred years. Physical and chemical properties of various elements occur in patterns throughout both groups/families, as well as the periods themselves. We can determine from these arrangements then, that these elements closer to each other in these rows and columns share many of the same characteristics, while those that are farther away from one another have very dissimilar properties. The elements in Group I and Group II are also known as Alkali and Alkaline Earth Metals because of their shared characteristics. One common property that each of these metals share is that they react strongly with other elements to accept or lose hydrogen ions. Acids and bases can be found in medicines, household cleaners, bleaches, detergents, drain cleaners, and even as preservatives in the foods that we eat. Acids differ from bases by the amounts of H+ and OH- ions they contain. A pH scale is a numeric scale from 0 to 14 that is used to distinguish between acids and bases, and their relative strengths. An acid is a material with a pH less than 7, while bases are those that are greater than 7. An object that is said to be neutral is one with a pH equal to 7. In chemistry, this means that substances that have a lower pH have a greater concentration of H+ ions, and are stronger acids. Bases are those substances with a greater concentration of OH- ions. Special paper called litmus paper can be used to identify acids and bases. The paper contains certain dyes that change to different colors according to the concentration of the ions present in the substances being tested. In this investigation, you will use pH paper to determine whether various household substance are acids or bases and how strongly acidic or basic they are. Materials: 1 pH Color Chart 7 strips of Litmus paper, torn in ½ Safety goggles Paper towels 0.25 M HCl (hydrochloric acid)
0.1 M NaOH (sodium hydroxide) Distilled water Corn Oil Lemon Juice Tomato Juice Milk Soda
Vinegar Rubbing Alcohol (diethyl alcohol) Milk of Magnesia Tap Water Ammonia Your own saliva!
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Procedure: 1. Before you begin, you must use your knowledge of the properties of acids and bases to predict which of the common household materials will be acids, which will be neutral, and which will be bases. Fill in your answers in the first column in the data collection table. 2. CAUTION: Put on safety goggles before handling any of the chemicals from this lab. If you get any chemicals on your skin, rinse immediately with plenty of cool water. 3. Place a piece of pH (litmus) paper on a dry paper towel. Place 1 drop of hydrochloric acid on the litmus paper. Note the color change in the litmus paper. What color does the litmus paper immediately turn to? _________________ Using your color chart, determine the pH of the acid and record the value in the appropriate space in the table below. What is the pH of HCl? ______________ 4. Place a fresh piece of litmus paper on a dry paper towel. Place 1 drop of sodium hydroxide on the litmus paper. What color does the litmus paper immediately turn to? _________________ Match the color of the paper to the color chart, and record the value in the table below. What is the pH of NaOH? ______________ 5. Place a fresh piece of litmus paper on a dry paper towel. Test a sample of distilled water by placing a drop of water on the pH paper with a clean dropper. Record your results in the table. What is the pH of the distilled water? ______________ What does this figure tell you about distilled water? __________________________________________ 6. Remembering to clean the dropper and to use fresh pH paper for each sample, test and record the pH values for the following substances: Distilled Water Vinegar Corn oil Rubbing Alcohol Lemon juice Milk of Magnesia Tomato juice Tap Water Milk Ammonia Soda Saliva
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Data Table: (14 points) Material Tested
Prediction: acid/neutral/base
Approximate Color
Results:
pH
Results: acid/neutral/base
Prediction is: Accepted
Rejected
Hydrochloric Acid (HCl) Sodium Hydroxide (NaOH) Distilled Water Corn Oil Lemon Juice Tomato Juice Orange Juice Milk Soda Vinegar Rubbing Alcohol Milk of Magnesia Tap Water Ammonia Saliva
7. On the pH scale below, enter the names of all of the substances tested. Place the names as closely as possible to their correct pH value. *Note: Remember to add sodium hydroxide and hydrochloric acid to the scale! (7 points)
STRONG ACID
NEUTRAL
STRONG BASE
Check for Understanding 1. Acids and Bases are found in the 1st and 2nd most reactive groups in the periodic table. In which groups (number and name) are acids and bases typically located? ________________________ ______________________________________________________________________________ 2. What scale do scientists use to tell how acidic or basic a substance is? ______________________ 3. What is the pH range for: a. Acidic substances? _____________ b. Neutral substances? _____________ c. Basic substances? _____________ 4. Acids have a greater concentration of __________________ ions, while bases have a greater concentration of _____________________ ions.
Conclusion Questions 1. Why do you think you were asked to include HCl and NaOH in a test of household products? ________________________________________________________________________________ ________________________________________________________________________________ 2. Lemons and oranges have nearly the same pH. Why might it be easier to eat an orange than a lemon? ________________________________________________________________________________ ________________________________________________________________________________ 3. Why are most body fluids (i.e. - saliva, blood, tears) have a pH that is neutral/almost neutral? ________________________________________________________________________________ ________________________________________________________________________________ Testing the pH of liquid substances in your cupboards and cabinets: Take home one strip of litmus paper and tear it into 6 small pieces. Paying close attention to the safety warnings on each substance, look in your home for 6 different liquid substances of which you wish to test the pH level. Fill in the chart below and glue or tape your litmus strips in the appropriate column, when they are dry. Name of Substance Tested
What is the substance used for?
Approximate Color
Results: pH #
Results: acid/neutral/base
Litmus Paper *Attached Here*
