Download Atoms Introduction

Tuesday, August 23, 2016
Atoms/Elements
Chemistry
1.) Which of the following is true about an individual atom?
a.) An individual atom should be considered to be a solid.
b.) An individual atom should be considered to be a liquid.
c.) an individual atom should be considered to be a gas.
d.) The state of the atom depends on which element it is.
e.) An individual atom cannot be considered to be a solid, liquid, or gas.
Justify your choice, and for choices you did not pick, explain what is wrong
with them.
2.) Which (if any) of the following can be determined by knowing the number
of protons in a neutral element? Explain your answer.
a.) The number of neutrons in the neutral element.
b.) The number of electrons in the neutral element.
c.) The name of the element.
3.) Which of the following explain how an ion is formed? Explain your
answer.
a.) Adding or subtracting protons to/from an atom.
b.) Adding or subtracting neutrons to/from an atom.
c.) Adding or subtracting electrons to/from an atom.
4.) A chemist in a galaxy far, far away performed the Millikan oil drop
experiment and got the following results for the charges on various drops.
Use these data to calculate the charge of the electron in zirkombs.
2.56 x 10-12 zirkombs
7.68 x 10-12 zirkombs
3.84 x 10-12 zirkombs
6.40 x 10-13 zirkombs
Tuesday, August 23, 2016
5.) Write the atomic symbol

A
Z
X  for each of the following isotopes.
a.) number of protons = 27, number of neutrons = 31
b.) the isotope of boron with mass number 10
c.) Z = 12, A = 23
d.) atomic number 53, number of neutrons = 79
e.) Z = 20, number of neutrons = 27
f.) number of protons = 29, mass number 65
6.) Complete the following table:
Number of Number of
Number of Net
Symbol Protons in Neutrons in
Electrons Charge
Nucleus
Nucleus
238
92
U
20
20
2+
23
28
20
35
44
36
15
16
89
39
Y
3-
Tuesday, August 23, 2016
7.) Naturally occurring iron has 4 primary isotopes. The information for each
isotope is presented in the table below.
Isotope
54
Fe
56
Fe
57
Fe
58
Fe
Atomic Mass Units (u)
53.9396127
55.9349393
56.9353958
57.9332773
Atom %
5.845
91.754
2.119
0.282
Using Example 3.1 as a guide, compute the average mass of iron
(u/atom). Show your work.
8.) The element magnesium (Mg) has three stable isotopes with the following
masses and abundances:
Isotope Mass (amu) Abundance
24
23.9850
78.99%
Mg
25
24.9858
10.00%
Mg
26
Mg
25.9826
11.01%
Calculate the average atomic mass (the atomic weight) of magnesium
from these data.
9.) The element europium exists in nature as two isotopes: 151Eu has a mass of
150.9196 amu, and 153 Eu has a mass of 152.9209 amu. The average
atomic mass of europium is 151.96 amu. Calculate the relative abundance
of the two europium isotopes.