# Introductory Chemistry

## Educators

Problem 1

Does the nucleus of an atom strongly affect its chemical properties? Explain.

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Problem 2

How large is a typical atomic nucleus, and how does the size of the nucleus of an atom compare with the
overall size of the atom?

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Problem 3

What does the atomic number of an atom represent?

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Problem 4

What does the mass number of a nucleus represent?

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Problem 5

What is meant by saying an element exists in several isotopic forms? Do isotopes of a given element have similar chemical properties? Explain.

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Problem 6

Using Z to represent the atomic number and A to represent the mass number, give the general symbol for
a nuclide of element X. Give also a specific example of the use of such symbolism.

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Problem 7

Write the nuclear symbol for an alpha particle.

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Problem 8

To which nuclear particle does the symbol $_{-1}$ e refer?

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Problem 9

When a nucleus emits a beta particle, by how many atomic mass units does the mass of the nucleus change? By how many units does the atomic number of the nucleus change? Explain.

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Problem 10

When a nucleus emits a neutron, does the atomic number of the nucleus change? Does the mass number of the nucleus change? Explain.

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Problem 11

What is a decay series?

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Problem 12

What changes, if any, take place to the atomic number and the mass number of an unstable nucleus
when the nucleus emits a gamma ray?

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Problem 13

What is a positron? What are the mass number and charge of a positron? How do the mass number and
atomic number of a nucleus change when the nucleus produces a positron?

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Problem 14

What do we mean when we say a nucleus has undergone an electron capture process? What type of electron is captured by the nucleus in this process?

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Problem 15

Naturally occurring sulfur consists primarily (94.9%) of the isotope with mass number 32, but small amounts of the isotopes with mass numbers 33, 34, and 36 also are present. Write the nuclear symbol for each of the isotopes of sulfur. How many neutrons are present in each isotope? Is the average atomic
mass of sulfur (32.07 g) consistent with the relative abundances of the isotopes?

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Problem 16

Although naturally occurring potassium consists mostly of the isotope of mass number 39 (93.25%), isotopes of mass number 41 (6.73%) and 40 (0.01%) also are present. Write the nuclear symbol for each of the isotopes of potassium. How many neutrons are present in each isotope? Is the average atomic mass of potassium (39.10 g) consistent with the relative abundances of the isotopes?

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Problem 17

Naturally occurring magnesium consists primarily of three isotopes, of mass numbers 24, 25, and 26. How many protons does each of these nuclides contain? How many neutrons does each of these nuclides contain? Write nuclear symbols for each of these isotopes.

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Problem 18

Consider the three isotopes of magnesium discussed in Exercise 17. Given that the relative natural abundances of these isotopes are 79%, 10%, and 11%, respectively, without looking at the inside cover of this book, what is the approximate atomic molar mass of magnesium? Explain how you made your prediction.

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Problem 19

Give the nuclear symbol for each of the following.
a. a beta particle
b. an alpha particle
c. a neutron
d. a proton

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Problem 20

Name the particle that has the following nuclear symbol.
.$$a-_{1}^{0} e \qquad c. -_{1}^{0} e \qquad b. _{1}^{0} \mathrm{e}\qquad d. ^{1}_{1} \mathrm{H}$$

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Problem 21

Complete each of the following nuclear equations by supplying the missing particle.
a. $226 \mathrm{Ra} \rightarrow ?+\frac{222}{8} \mathrm{Rn}$
b. $^{9} \mathrm{Be}+_{1}^{1} \mathrm{H} \rightarrow ?+_{2}^{4} \mathrm{He}$
c. $^{17}_{8} \mathrm{O}+? \rightarrow_{6}^{14} \mathrm{C}+_{1}^{3} \mathrm{H}$

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Problem 22

Complete each of the following nuclear equations by supplying the missing particle.
a. $^{23}_{13} \mathrm{Al} \rightarrow_{+1}^{0} \beta+?$
b. $^{1}_{1} \mathrm{H}+_{2}^{4} \mathrm{He} \rightarrow ?$
c. $_{14}^{28} \mathrm{Si}+_{0}^{1} \mathrm{n} \rightarrow \frac{25}{12} \mathrm{Mg}+?$

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Problem 23

Complete each of the following nuclear equations by supplying the missing particle.
a. $^{210}_{89} \mathrm{Ac} \rightarrow_{2}^{4} \mathrm{He}+?$
b. $^{131}_{53} \mathrm{I} \rightarrow_{54}^{131} \mathrm{Xe}+?$
c. $_{35}^{88} \mathrm{Br} \rightarrow_{35}^{87} \mathrm{Br}+?$

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Problem 24

Complete each of the following nuclear equations by supplying the missing particle.
a. $^{23}_{13} \mathrm{Al} \rightarrow_{+1}^{0} \beta+?$
b. $^{1}_{1} \mathrm{H}+_{2}^{4} \mathrm{He} \rightarrow ?$
c. $_{14}^{28} \mathrm{Si}+_{0}^{1} \mathrm{n} \rightarrow \frac{25}{12} \mathrm{Mg}+?$
d. $^{137}_{57} \mathrm{La}+^{0}_{-1} \mathrm{e} \rightarrow ?$

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Problem 25

Each of the following nuclides is known to undergo radioactive decay by production of a beta particle, $^{0}_{-1}{e}$ . Write a balanced nuclear equation for each process.
a. $^{14}_{6} \mathrm{C}$ $\quad$ b. $_{55}^{140} \mathrm{Cs}$ $\quad$ c. $^{234}_{90} \mathrm{Th}$

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Problem 26

Each of the following nuclides is known to undergo radioactive decay by production of an alpha particle,
$^{4}_{2} \mathrm{He}$ . Write a balanced nuclear equation for each process.
$\begin{array}{lll} {\text { b. }^{234}_{92} \mathrm{U}} & {\text { b. } ^{222}_{86} \mathrm{Rn}} & {\text { c. } ^{162}_{75} \mathrm{Re}}\end{array}$

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Problem 27

Each of the following nuclides is known to undergo radioactive decay by production of a beta particle, $^{0}_{-1} \mathrm{e}$ . Write a balanced nuclear equation for each process.
a. $\underset{74}{188} \mathrm{W}$ $\quad$ b. $^{222}_{86} \mathrm{Rn}$$\quad$ c. $\underset{79}{198} \mathrm{Au}$

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Problem 28

Each of the following nuclides is known to undergo radioactive decay by production of a beta particle, $^{0}_{-1} \mathrm{e}$ . Write a balanced nuclear equation for each process.
a. $^{212}_{82} \mathrm{Pb}$ $\quad$ b. $^{212}_{81} \mathrm{Tl}$ $\quad$ c.$^{228}_{88}\mathrm{Ra}$

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