$$12.01 + 2 \times 16.00 = 44.01$$ amu

Question 1

Which of the following statements best describes the modern atomic theory?

Accepted Answer

Atoms are the smallest form of stable matter and combine in whole-number ratios to form compounds.

Question 2

Which subatomic particle is responsible for the identity of an element?

Accepted Answer

Proton

Question 3

A neutral atom of magnesium has an atomic number of 12 and a mass number of 24. How many neutrons does it have?

Accepted Answer

$$24 - 12 = 12$$

Question 4

Which of the following is the correct symbolic (isotopic) notation for an atom of oxygen with 8 protons and 10 neutrons?

Accepted Answer

$$^{18}_{8}\mathrm{O}$$

Question 5

Which of the following best describes an isotope?

Accepted Answer

Atoms of the same element with different numbers of neutrons.

Question 6

What is the molecular mass of $$\mathrm{CO}_2 ($$carbon dioxide)? (Atomic masses: C = 12.01 amu, O = 16.00 amu)

Accepted Answer

$$12.01 + 2 	imes 16.00 = 44.01$$ amu

Question 7

Which of the following is a correct name for the compound $$\mathrm{N}_2\mathrm{O}_5$$?

Accepted Answer

Dinitrogen pentoxide

Question 8

A sodium atom loses one electron to form an ion. What is the charge and name of this ion?

Accepted Answer

Positive, sodium cation

Question 9

Which of the following formulas represents an ionic compound formed between magnesium and nitrogen?

Accepted Answer

$$\mathrm{Mg}_3\mathrm{N}_2$$

Question 10

What is the correct name for the compound $$\mathrm{FeCl}_3$$?

Accepted Answer

Iron(III) chloride

Question 11

Which of the following statements about the structure of an atom is correct?

Accepted Answer

Protons and neutrons are clustered in the nucleus, while electrons occupy the electron cloud.

Question 12

Which of the following is the correct formula for barium chloride?

Accepted Answer

$$\mathrm{BaCl}_2$$

Question 13

A chlorine atom gains one electron. What is the resulting ion called?

Accepted Answer

Chloride ion

Question 14

Which of the following is a diatomic molecule?

Accepted Answer

$$\mathrm{O}_2$$

Question 15

What is the total number of electrons in a neutral atom of calcium (atomic number 20)?

Accepted Answer

$$20$$

Question 16

Which of the following best explains why ionic compounds are electrically neutral?

Accepted Answer

The total positive charge equals the total negative charge.

Question 17

What is the correct name for $$\mathrm{SiO}_2$$?

Accepted Answer

Silicon dioxide

Question 18

Which of the following is the correct formula for copper(I) nitride?

Accepted Answer

$$\mathrm{Cu}_3\mathrm{N}$$

Question 19

If a neutral atom of sulfur (atomic number 16) gains two electrons, what is the symbol and charge of the resulting ion?

Accepted Answer

$$\mathrm{S}^{2-}$$

Question 20

Which of the following is the correct name for $$\mathrm{N}_2\mathrm{O}_4$$?

Accepted Answer

Dinitrogen tetroxide

Atoms, Molecules, and Ions: Foundations of Chemistry

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