Question 1

Which of the following statements best explains why sodium (Na) forms a $$+1$$ ion when it reacts with chlorine (Cl) to form table salt?

Accepted Answer

Sodium has one valence electron, which it loses to achieve a stable octet configuration.

Question 2

Which of the following ions is isoelectronic with neon ($$\mathrm{Ne}$$)?

Accepted Answer

$$\mathrm{Na^+}$$

Question 3

A magnesium atom ($$\mathrm{Mg}) $$reacts to form an ion. What is the correct symbol for this ion, and how many electrons does it have?

Accepted Answer

$$\mathrm{Mg$$^{2+}$$}$$, 10 electrons

Question 4

Which of the following best describes the octet rule?

Accepted Answer

Atoms tend to gain, lose, or share electrons to achieve eight electrons in their valence shell.

Question 5

What is the correct formula for the ionic compound formed between calcium and phosphorus?

Accepted Answer

$$\mathrm{Ca_3P_2}$$

Question 6

Which of the following correctly names the compound $$\mathrm{$$FeCl_3$$}$$?

Accepted Answer

iron(III) chloride

Question 7

A student writes the formula for magnesium oxide as $$\mathrm{$$MgO_2$$}. $$What is the error in this formula?

Accepted Answer

The charges are not balanced; the correct formula is $$\mathrm{MgO}.$$

Question 8

Which of the following best describes the structure and properties of a solid?

Accepted Answer

Particles are close together in a fixed arrangement and move very slowly.

Question 9

Which of the following ions has the same number of electrons as an argon atom ($$\mathrm{Ar}$$)?

Accepted Answer

$$\mathrm{K^+}$$

Question 10

What is the correct name for the ion $$\mathrm{N$$^{3-}$$}$$?

Accepted Answer

nitride ion

Question 11

Which of the following statements about ionic compounds is FALSE?

Accepted Answer

They have low melting points.

Question 12

A student is asked to write the formula for aluminum oxide. Which of the following is correct, and why?

Accepted Answer

$$\mathrm{Al_2O_3}$$, because aluminum forms $$+3$$ ions and oxygen forms $$-2$$ ions, so the charges balance.

Question 13

Which of the following best explains why chlorine ($$\mathrm{Cl}) $$forms a $$-1$$ ion?

Accepted Answer

Chlorine gains one electron to achieve a stable octet.

Question 14

Which of the following is the correct formula for potassium bromide?

Accepted Answer

$$\mathrm{KBr}$$

Question 15

Which of the following best describes the difference between a cation and an anion?

Accepted Answer

A cation is positively charged, while an anion is negatively charged.

Question 16

Which of the following elements would you expect to form a $$2-$$ ion?

Accepted Answer

sulfur

Question 17

Which of the following is the correct name for $$\mathrm{CuO}$$, given that copper can have multiple charges?

Accepted Answer

copper(II) oxide

Question 18

A sample of water is heated and changes from a liquid to a gas. Which of the following best describes this change?

Accepted Answer

It is a physical change because the state changes but the chemical composition remains the same.

Question 19

Which of the following best describes the arrangement and movement of particles in a gas?

Accepted Answer

Particles are far apart and move rapidly.

Unit 2: Ions, Ionic and Molecular Compounds, and Changes of State

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