Name: ___________________________________
Date: __________________ Period: ___________
How Atoms Differ
1. Define an atom. __________________________________________________________
_______________________________________________________________________.
2. Which subatomic particle identifies an atom as that of a particular element? How is this
particle related to the atom’s atomic number? __________________________________
_______________________________________________________________________
_______________________________________________________________________.
3. What happens if the number of protons an atom has changes?
_______________________________________________________________________.
4. What is an isotope? Give an example of an element with isotopes.
_______________________________________________________________________
_______________________________________________________________________.
5. Dalton believed that all atoms of the same element were identical. Does the existence of
isotopes contradict this part of Dalton’s original atomic theory? Explain.
_______________________________________________________________________
_______________________________________________________________________
_______________________________________________________________________.
6. How do isotopes of a given element differ? How are they similar?
_______________________________________________________________________
_______________________________________________________________________.
7. In the isotope notation below, label the superscript, subscript, and letter according to
what they represent.
40
19
K
Name: ___________________________________
Date: __________________ Period: ___________
8. Nitrogen has two naturally occurring isotopes, nitrogen-14 and nitrogen-15. The atomic
mass of nitrogen is 14.007 amu. Which isotope is more abundant in nature? Explain.
_______________________________________________________________________
_______________________________________________________________________
_______________________________________________________________________.
9. How many e-, p+, and n0 are contained in each of the following atoms?
a.
132
b.
59
Cs
________ e-
________ p+
_________ n0
Co
________ e-
________ p+
_________ n0
55
27
10. How many e-, p+, and n0 are contained in each of the following atoms?
a. gallium-64
________ e-
________ p+
_________ n0
b. fluorine-23
________ e-
________ p+
_________ n0
11. Silver has two isotopes.
107
47
Ag has a mass of 106.905 amu (52.00%) and
109
47
Ag has
a mass of 108.905 amu (48.00%). What is the atomic mass of silver? Show all your
work!
12. Data for chromium’s four naturally occurring isotopes is provided in the table below.
Calculate chromium’s atomic mass. Show all your work!
Chromium Isotope Data
Isotope
Percent
Abundance
Mass (amu)
chromium-50
4.35%
49.946
chromium-52
83.79%
51.941
chromium-53
9.50%
52.941
chromium-54
2.36%
53.939