Question 1

Which of the following statements best explains why the mass number ($$A) of an $$atom is usually a whole number, while the atomic mass listed on the periodic table is often a decimal?

Accepted Answer

The mass number is the sum of protons and neutrons in a single atom, while atomic mass is the weighted average of all naturally occurring isotopes.

Question 2

Which of the following ions is a polyatomic ion with a $$-2$$ charge?

Accepted Answer

Carbonate, $$\mathrm{CO_3$^{2-}}$$

Question 3

A neutral atom of chlorine has an atomic number $$Z = 17$$ and a mass number $$A = 37. $$How many neutrons does it contain?

Accepted Answer

$$20$$

Question 4

Which of the following best describes the difference between ionic and covalent compounds?

Accepted Answer

Ionic compounds are held together by electrostatic attraction between ions, while covalent compounds are held together by shared electrons.

Question 5

Which of the following is the correct formula for iron(III) sulfate?

Accepted Answer

$$\mathrm{Fe_2$(SO_4$)_3}$$

Question 6

Which of the following compounds is named correctly?

Accepted Answer

CO: carbon monoxide

Question 7

A sample contains $$2.0$$ moles of $$\mathrm{NaCl}. $$How many formula units are present in the sample? ($$N_A = 6.022 	imes 10$$^{23}$$)

Accepted Answer

$$1.2 	imes 10$$^{24}$$

Question 8

Which of the following statements about valence electrons is correct?

Accepted Answer

Valence electrons determine the chemical reactivity of an element.

Question 9

Which of the following best explains why sodium forms a $$+1$$ ion and chlorine forms a $$-1$$ ion in $$\mathrm{NaCl}$$?

Accepted Answer

Sodium loses one electron to achieve a noble gas configuration, while chlorine gains one electron.

Question 10

Which of the following is a correct example of a Type II cation and its name?

Accepted Answer

$$\mathrm{Fe$$^{2+}$$}$$: iron(II)

Question 11

Which of the following is the correct name for $$\mathrm{N_2O_5}$$?

Accepted Answer

Dinitrogen pentoxide

Question 12

Which of the following statements about the periodic table is true?

Accepted Answer

Halogens are found in Group 17.

Question 13

Which of the following is a homogeneous mixture?

Accepted Answer

Salt water

Question 14

Which of the following is the correct formula for ammonium carbonate?

Accepted Answer

$$\mathrm{(NH_4$)_2CO_3}$$

Question 15

Which of the following best describes why Roman numerals are used in the names of some ionic compounds?

Accepted Answer

To indicate the charge of a Type II cation that can have more than one possible charge.

Question 16

Which of the following is the correct formula for chromium(VI) oxide?

Accepted Answer

$$\mathrm{$$CrO_3$$}$$

Question 17

Which of the following is NOT one of the seven diatomic elements?

Accepted Answer

Sulfur

Question 18

A sample of hydrogen peroxide contains $$3.0$$ grams of $$\mathrm{O_2$^{2-}}$$ ions. If the molar mass of $$\mathrm{O_2$^{2-}} is$$ $$32.0 g/$$mol, how many moles of $$\mathrm{O_2$^{2-}}$$ are present?

Accepted Answer

$$0.094$$ moles

Question 19

Which of the following best describes where most of the mass and most of the volume of an atom are located?

Accepted Answer

Most of the mass is in the nucleus; most of the volume is in the electron cloud.

Question 20

Which of the following is the correct name for $$\mathrm{K_2CrO_4}$$?

Accepted Answer

Potassium chromate

Atoms, Ions, Compounds, and Nomenclature: Exam 2 Study Guide

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