Practice Test (Key)
I. Matching
Column A
__J__ 1. electron
__C__ 2. nucleus
__E__ 3. isotopes
__G__ 4. atomic number
__A__ 5. mass number
__H__ 6. ion
__D__ 7. neutron
__B__ 8. proton
Column B
A. sum of the number of protons and the number of neutrons in the nucleus of an
atom
B. positively charged subatomic particle
C. dense, positively charged center of atom
D. subatomic particle with zero charge
E. atoms with same number of protons but different numbers of neutrons
F. negatively charged ion
G. number of protons in the nucleus of an atom
H. atom with a charge
I. positively charged ion
J. negatively charged subatomic particle
II. Multiple Choice Choose the one best answer and write its letter in the blank. (2pts each)
__B__ 9) Which of the following is a compound?
a) Fe
b) CO
c) O2
d) K
__D__ 10) Which element’s symbol begins with a different letter than its name?
a) oxygen b) neon
c) fluorine
d) sodium
__D__ 11) Which is the most abundant element (by mass) in the earth’s crust?
a) carbon b) silicon
c) neon d) oxygen
__C__ 12) Which of the following is NOT part of Dalton’s atomic theory?
a) all elements are composed of atoms
b) atoms of the same element are identical
c) atoms are in constant motion
d) when atoms combine they do so in simple whole number ratios
__C__ 13) The element chlorine belongs to which of the following groups?
a) alkali metals
b) noble gases
c) halogens
d) alkaline earth metals
__B__ 14) Which of the statements (a - c) is NOT true about a carbon-14 atom?
a) It contains 6
b) It contains 6 neutrons. d) All of the above are true.
protons.
c) It contains 6 electrons.
__D__ 15) An ion always contains
a) equal numbers of protons and electrons
b) equal numbers of protons and neutrons
c) unequal numbers of protons and neutrons
d) unequal numbers of protons and electrons
__C__ 16) The identity of an element is determined by its
a) mass number
b) number of neutrons
c) atomic number
__B__ 17) Which of the following statements is true?
a) the proton and the neutron have opposite charges
b) the proton and the electron have opposite charges
c) the electron and the neutron are found in the nucleus
d) atoms gain or lose protons when they form ions
__A__ 18) Which of these atoms has the greatest number of neutrons in its nucleus?
d) atomic mass
III. Short Answer
19)
chlorine ion
Cl
17
35
hydrogen ion
H
1
1
11
11
12
23
-1
0
11
0
Calculations: (Work must be shown for credit)
20) What is average atomic mass of Lithium if 7.42% exists as 6Li (6.015 amu) and 92.58% exists as 7Li (7.016 amu)?
(7.42)(6.015 amu) + (92.58)(7.016 amu)
= 6.94 amu
100
21) Neon has two major isotopes, Neon-20 and Neon-22. Out of every 250 neon atoms, 225 will be Neon-20 (19.992 amu),
and 25 will be Neon-22 (21.991 amu). What is the average atomic mass of Neon?
(225)(19.992 amu) + (25)(21.991 amu)
= 20.192 amu
250
22) What is the atomic mass of Hafnium if out of every 200 atoms, 10 have mass 176.00 amu, 38 have mass
177.00 amu, 54 have mass 178.00 amu, 28 have mass 179.00 amu, and 70 have mass 180.00 amu?
(10)(176.00 amu) + (38)(177.00 amu) + (54)(178.00 amu) + (28)(179.00 amu) + (70)(180.00 amu)
= 178.55 amu
200