Name
Date
Class
Key Concept Builder
LESSON 1
Discovering Parts of an Atom Key Concept What is an atom? Directions: Label this diagram by writing the correct term from the word bank on each line.
electron cloud
neutron
nucleus
proton 3.
1.
4.
2.
Directions: Answer each question or respond to each statement on the lines provided.
5. Early Greeks, such as Aristotle, thought all matter was made of which four elements?
Copyright © Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc.
6. How do modern scientists describe the makeup of matter?
7. Define atom.
8. Identify the parts of an atom.
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Understanding the Atom
Name
Date
Key Concept Builder
Class
LESSON 1
Discovering Parts of an Atom Key Concept How would you describe the size of an atom?
Copyright © Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc.
Directions: Each set of items includes one that is larger than the other. Circle the larger item in each set of items.
1. atom
neutron
2. quark
neutron
3. nucleus
atom
4. nucleus
proton
5. electron cloud
atom
6. electron
nucleus
7. atom
electron
8. proton
atom
9. nucleus
neutron
10. proton
quark
Directions: Answer each question on the lines provided.
11. Is it possible to see atoms with your eyes? Explain.
12. What is an STM?
13. How have STMs helped scientists study atoms?
Understanding the Atom
19
Name
Date
Class
Key Concept Builder
LESSON 1
Discovering Parts of an Atom Key Concept How has the atomic model changed over time? Directions: Complete the chart by writing the name of the person who developed each theory.
Name of Developer
Theory • Atoms are small solid objects that cannot be divided, created, or destroyed. • Atoms are constantly moving in empty space. • Different types of matter are made of different types of atoms.
2.
• Empty space does not exist. • Matter is made of fire, water, air, and earth.
3.
• During a chemical reaction, atoms of one element cannot be converted into atoms of another element. • Atoms of one element are identical to each other and different from atoms of another element. • Atoms combine in specific ratios.
4.
• An atom is a sphere that contains positive and negative charges. • The positive charge is evenly spread throughout the atom. • Negatively charged electrons are mixed through the positive charge.
5.
• Most of an atom’s mass and positive charge is concentrated in a small area in the center of the atom called the nucleus. • The nucleus contains positively charged particles called protons. • Negatively charged electrons move in the empty space surrounding the nucleus.
6.
• In addition to protons, the nucleus contains neutrons. • Neutrons are neutral particles that exist in the nucleus of the atom.
7.
• Electrons move in circular orbits, or energy levels, around the nucleus. • Electrons that are closer to the nucleus have less energy than electrons that are farther away from the nucleus.
20
Understanding the Atom
Copyright © Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc.
1.
Name
Date
Key Concept Builder
Class
LESSON 1
Discovering Parts of an Atom Key Concept How has the atomic model changed over time? Directions: Place the events in chronological order from earliest to most recent by writing a number 1 through 7 on the line before the statement that describes each event.
J.J. Thomson investigates the electrical charges of atoms.
Democritus challenges the popular idea that matter is made of fire, water, air, and earth.
Niels Bohr investigates the energy level of electrons.
Students of Ernest Rutherford conduct the gold foil experiment.
Copyright © Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc.
John Dalton finds evidence to support the theory that all matter is made of atoms that cannot be divided, created, or destroyed.
Scientists discover that protons and neutrons are made of quarks.
James Chadwick discovers that in addition to protons, the nucleus also contains neutrons. Directions: Answer each question on the lines provided.
8. Where are electrons found in the modern atomic model?
9. Do you think that the modern atomic model will change in the future? Explain.
Understanding the Atom
21
