Completion
1.
According to Dalton’s atomic theory, elements are composed of tiny particles called
_______________.
2.
Atoms of each element are ________________ from the atoms of all other elements. Atoms of different elements can form _______________ by combining in whole-number ratios.
3.
Chemical reactions occur when _____________ are separated, joined, or rearranged.
True-False
(State whether each is true or false and give a justification below as to why or why not)
________ 4. Atoms of one element change into atoms of another element during
chemical reactions.
________ 5. Atoms combine in one-to-one ratios to form compounds.
________ 6. Atoms of one element are different from atoms of other elements.
7. In what type of ratios do atoms combine to form compounds?
8. How many copper atoms would you have to line up side by side to form a line 1 m long if
100,000,000 copper atoms side by side would produce a line only 1 cm long?

Matching
(Match each description in Column B to the correct term in Column A)
Column A
________ 9. atom
________ 10. Dalton’s atomic theory
________ 11.
John Dalton
________ 12.
Democritus
Column B a. theory to explain the reactive behavior of elements b. teacher in ancient Greece c. the smallest particle of an element that retains the
properties of that element. d. 19th-century English school teacher who formulated a
theory to describe the structure and chemical reactivity
of matter in terms of atoms

Completion
1.
Dalton theorized that atoms are indivisible, but the discovery of
_______________ particles changed this theory. Scientists now know that atoms are made up of electrons, which have a _____________ charge; _____________, which have a positive charge; and _____________, which are neutral. The latter two particles are found in the ______________ of the atom.
2.
It was __________________ who discovered the nucleus of the atom. The nucleus, which has a ______________ charge, occupies a very small volume of the atom. In contrast, the negatively charged ______________ occupy most of the volume of the atom.
True-False
(State whether each is true or false and give a justification below as to why or why not)
______ 4. According to Dalton’s atomic theory, atoms are composed of protons,
electrons, and neutrons.
______ 5. Atoms of elements are electrically neutral.
______ 6. The mass of an electron is equal to the mass of a neutron.
______ 7. The charge on all protons is the same.
8. Which subatomic particles are found in the nucleus of an atom?
9. Which subatomic particles are charged?

10. Describe Rutherford’s model of the atom, including the location of protons, neutrons, and electrons with respect to the nucleus. How does this model explain the deflection of alpha particles by gold foil?
Matching
(Match each description in Column B to the correct term in Column A)
Column A
________ 11. electrons
________ 12. cathode ray
________ 13. protons
________ 14. neutrons
________ 15. nucleus
Column B a. a beam that travels from a cathode to an anode b. the central core of an atom, which is composed of
protons and neutrons c. negatively charged subatomic particles d. subatomic particles with no charge e. positively charged subatomic particles.

1.
The number of ____________ in the nucleus of an atom is the atomic
____________ of that element. Because atoms are electrically neutral, the number of protons and ____________ in an atom are equal.
2.
The sum of the _____________ and neutrons is the mass number.
3.
Atoms of the same element are identical in most respects, but they can differ in the number of ____________ in the nucleus. Atoms that have the same number of protons but different mass numbers are called _______________.
4.
The __________________ of an element is the weighted average of the masses of the isotopes of that element. Each of the three known isotopes of hydrogen has
_________ proton(s) in the nucleus. The most common hydrogen isotope has
_________ neutrons. It has an atomic mass of ________ amu and is called hydrogen-1.
True-False
(State whether each is true or false and give a justification below as to why or why not)
________ 5. The atomic number of an element is the sum of the protons and
electrons in an atom of that element.
________ 6. The atomic number of an atom is the total number of protons in an
atom of that element.
________ 7. An atom of nitrogen has 7 protons and 7 neutrons.
________ 8. Relative atomic masses are expressed in amus.
________ 9. The number of neutrons in the nucleus can be calculated by
subtracting the atomic number from the mass number.

Matching
(Match each description in Column B to the correct term in Column A)
Column A
________ 10. atomic number
________ 11. mass number
________ 12. isotopes
________ 13. atomic mass unit (amu)
________ 14. atomic mass
Column B a. atoms that have the same number of protons but
different numbers of neutrons b. weighted average mass of the atoms in a naturally
occurring sample of an element c. the total number of protons and neutrons in an atom d. one-twelfth the mass of a carbon-12 atom e. the number of protons in the nucleus of an atom of
an element
15. How many neutrons are in the following atoms? a.
108 Ag
47 b.
80
35
Br c.
207 Pb
82
16. Express the composition of each atom in shorthand form a.
fluorine-19 b.
beryllium-9

17. Identify the number of electrons for each of the following a.
16 O
8 b.
32 S
16 c.
108 Ag
47

1. Given the relative abundance of the following naturally occurring isotopes of oxygen,
calculate the average atomic mass of oxygen: oxygen-16: 99.76% oxygen-17: 0.037% oxygen-18: 0.204%
2. There are three isotopes of silicon; they have mass numbers of 28, 29, and 30. The atomic mass of silicon is 28.086 amu. Comment on the relative abundance of these three isotopes.
3. The element copper has naturally occurring isotopes with mass numbers of 63 and 65.
The relative abundance and atomic masses are 69.2% for mass= 62.93 amu, and 30.8% for mass= 64.93 amu. Calculate the average atomic mass of copper.

4. An atom is identified as platinum-195 a.
What does this number represent? b.
Symbolize this atom using superscripts and subscripts
5. List the number of protons, electrons, and neutrons in each pair of isotopes a.
6 Li 7 Li
3 3 b.
42 Ca 44 Ca
20
20 c.
78 Se 80 Se
34 34
6. The atomic masses of elements are generally not whole numbers. Explain why.