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 elements has 6 valence electrons and would most likely form a $$2-$$ anion?

Accepted Answer

Oxygen ($$O)$$

Question 3

A neutral atom of phosphorus ($$P) $$has an atomic number of 15. How many electrons are in its outermost shell?

Accepted Answer

$$5$$

Question 4

Which of the following correctly represents the electron-dot (Lewis) symbol for magnesium ($$Mg$$)?

Accepted Answer

$$Mg$$ with two dots on one side

Question 5

What is the correct formula for the ionic compound formed between calcium ($$Ca^{2+}) $$and phosphorus ($$P^{3-}$$)?

Accepted Answer

$$Ca_3P_2$$

Question 6

Which of the following best describes the octet rule?

Accepted Answer

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

Question 7

A sample of magnesium reacts with oxygen to form magnesium oxide. Which of the following is the correct formula for magnesium oxide?

Accepted Answer

$$MgO$$

Question 8

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

Accepted Answer

$$F^-$$

Question 9

What is the correct name for the compound $$FeCl_3$$?

Accepted Answer

Iron(III) chloride

Question 10

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 11

Which of the following is the correct formula for the compound formed between aluminum ($$Al^{3+}) $$and oxygen ($$O^{2-}$$)?

Accepted Answer

$$Al_2O_3$$

Question 12

Which of the following statements about ionic compounds is FALSE?

Accepted Answer

They have low melting points.

Question 13

A student writes the formula for potassium bromide as $$K_2Br. $$What is the error in this formula?

Accepted Answer

Potassium forms a $$+1$$ ion and bromide forms a $$-1$$ ion, so the correct formula is $$KBr.$$

Question 14

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

Accepted Answer

Chlorine gains one electron to achieve a stable octet.

Question 15

Which of the following is the correct name for $$Mg_3N_2$$?

Accepted Answer

Magnesium nitride

Question 16

Which of the following best describes a gas?

Accepted Answer

Particles are far apart, move rapidly, and fill the volume of the container.

Question 17

Which of the following is the correct formula for lead(IV) oxide?

Accepted Answer

$$PbO_2$$

Question 18

Which of the following ions would have the same number of electrons as an atom of argon ($$Ar$$)?

Accepted Answer

$$Cl^-$$

Question 19

A student is asked to write the formula for chromium(III) iodide. Which of the following is correct?

Accepted Answer

$$CrI_3$$

Question 20

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.

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

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