$$1.51 \times 10$$^{24}$$ atoms

Question 1

Which of the following statements best describes the octet rule?

Accepted Answer

Atoms tend to gain, lose, or share electrons to achieve eight electrons in their outermost energy level.

Question 2

What is the maximum number of electrons that can occupy the third energy level ($$n=3) of an $$atom?

Accepted Answer

$$18$$

Question 3

A neutral atom of oxygen has 8 protons and 8 electrons. If it gains two electrons, what is the resulting charge and electron count?

Accepted Answer

Charge: $$-2$$, Electrons: $$10$$

Question 4

Which of the following ions is isoelectronic with neon ($$Ne$$)?

Accepted Answer

$$F^-$$

Question 5

What is the formula for the ionic compound formed between magnesium and nitrogen?

Accepted Answer

$$Mg_3N_2$$

Question 6

Which of the following correctly names the compound $$CuO$$?

Accepted Answer

Copper(II) oxide

Question 7

How many moles are present in $$36.03$$ grams of water ($$H_2O$$)? (Molar mass of $$H_2O = 18.02 g/$$mol)

Accepted Answer

$$2.00$$ moles

Question 8

Which of the following molecules has a bent shape according to VSEPR theory?

Accepted Answer

$$H_2O$$

Question 9

What is the electronegativity difference required for a bond to be considered ionic?

Accepted Answer

Greater than or equal to $$1.8$$

Question 10

Which of the following compounds is a polar molecule?

Accepted Answer

$$H_2O$$

Question 11

What is the correct name for the covalent compound $$N_2O_4$$?

Accepted Answer

Dinitrogen tetraoxide

Question 12

Which of the following statements about polyatomic ions is TRUE?

Accepted Answer

Polyatomic ions are groups of nonmetals with a net charge.

Question 13

How many atoms are present in $$2.5$$ moles of sodium ($$Na$$)? ($$N_A = 6.02 	imes 10$$^{23}$$ atoms/mol)

Accepted Answer

$$1.51 	imes 10$$^{24}$$ atoms

Question 14

Which of the following best explains why $$CH_4 ($$methane) is a nonpolar molecule?

Accepted Answer

The molecule is tetrahedral and the bond dipoles cancel out.

Question 15

What is the molar mass of $$C_6H_{12}O_6$ (glucose)? (C: 12.01 g/mol, H: 1.01 g/mol, O: 16.00 g/mol)

Accepted Answer

$$180.16 g/$$mol

Question 16

Which of the following is the correct Lewis structure for $$NH_3$$?

Accepted Answer

Nitrogen with three single bonds to hydrogen and one lone pair.

Question 17

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

Accepted Answer

Ionic compounds result from electron transfer between metals and nonmetals; covalent compounds result from electron sharing between nonmetals.

Question 18

If a transition metal forms more than one ion, how is the charge indicated in the compound's name?

Accepted Answer

By a Roman numeral in parentheses after the metal's name.

Question 19

Which of the following bonds is considered nonpolar?

Accepted Answer

$$C-H$$

Question 20

A molecule has a central atom with three charge clouds and no lone pairs. What is its molecular geometry?

Accepted Answer

Trigonal planar

Chapter 3: Compounds—How Elements Combine (GOB Chemistry Study Notes)

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