Chapter 4 - Atoms
Ancient Greek Models of Atoms (page 100)
they could not be divided.
Dalton’s Atomic Theory (page 101)
2. Is the following sentence true or false? John Dalton gathered evidence
for the existence of atoms by measuring the masses of elements that
reacted to form compounds.
3. Dalton’s theory suggests that all matter is made up of individual
particles called , which cannot be .
4. Circle the letters of the sentences that represent main points of Dalton’s
theory of atoms.
a. All elements are composed of atoms.
b. In a particular compound, atoms of different elements always
combine the same way.
c. All atoms have the same mass.
Thomson’s Model of the Atom (pages 102–103)
5. Use the words in the box below to fill in the blanks. Objects with like
electric charges ______, and objects with opposite electric
charges . ______
attract deflect
reflect repel
6. Thomson concluded that the particles in the glowing beam had a(n)
------charge because they were attracted to a positiveplate.
7. Circle the letter of the sentences that describe Thomson’s model of the
atom.
a. An atom is filled with positive matter.
b. An atom is mostly space with a small nucleus.
c. Negative charges are scattered throughout an atom.
Rutherford’s Atomic Theory (pages 104–105)
8. An ______is a fast-moving particle that carries a positive charge.
9. Circle the letters of the sentences that describe what happened when
Marsden directed a beam of particles at a piece of gold foil.
a. More alpha particles were deflected than expected.
b. None of the alpha particles were deflected.
c. Some alpha particles bounced back toward the source.
10. Circle the letter of the sentence that states what Rutherford
concluded from the gold foil experiment.
a. An atom’s negative charge is concentrated in its nucleus.
b. An atom’s positive charge is concentrated in its nucleus.
c. An atom’s positive charge is spread evenly throughout the atom.
Properties of Subatomic Particles (pages 108–109)
1. What are three subatomic particles?
a. ______
b. ______
c. ______
2. Circle the letter that identifies a subatomic particle with a positive
charge.
a. nucleus
b. proton
c. neutron
Comparing Subatomic Particles (pages 109–110)
3. Circle the letters of properties that vary among subatomic particles.
a. color
b. location in the atom
c. charge
4. Circle the letter of the expression that accurately compares the masses of
neutrons and protons.
a. mass of 1 neutron = mass of 1 proton
b. mass of 2000 neutrons = mass of 1 proton
c. mass of 1 electron = mass of 1 proton
Atomic Number and Mass Number (page 110)
5. Is the following sentence true or false? Two atoms of the same element
can have different numbers of protons.
6. The______number of an element equals the number of protons in
an atom of that element.
7. Is the following sentence true or false?
Two different elements can have the same atomic number.
8. The ______number of an atom is the sum of the protons and
neutrons in the nucleus of that atom.
9. Complete the equation in the table below.
Number of neutrons ______= Mass number
Isotopes (page 112)
Use the words below to fill in the blanks in questions 10–12.
Electrons isotopes
Neutrons protons
10. Every atom of a given element has the same number of ______
And______.
11. Every atom of a given element does not have the same number of ______
12. ______are atoms of the same element that have different
numbers of neutrons and different mass numbers.
13. All oxygen atoms have 8 protons. Circle the letter of the number of
neutrons in an atom of oxygen-18.
a. 8
b. 10
c. 18
14. Is the following sentence true or false? Isotopes of oxygen have
different chemical properties.
WordWise
Use the clues and the words below to help you write the vocabulary terms from
Chapter 4 in the blanks. Then find and circle the terms in the puzzle. The terms
may occur vertically, horizontally, or diagonally.