Ch. 5: Molecules and Compounds

Question 1

T/F: When elements combine to form compounds, their properties only change slightly.

Answer 1

False

Question 2

T/F: The properties of a compound are an average of the properties of the individual elements.

Answer 2

False

Question 3

T/F: Life could not exist with just 91 elements if they did not combine to form compounds.

Answer 3

True

Question 4

T/F: Although some substances we encounter in our routine lives are elements, most occur in the combined state.

Answer 4

True

Question 5

T/F: The law of constant composition states: All samples of a given compound have the same proportions of their constituent elements.

Answer 5

True

Question 6

T/F: The fact that water has an oxygen-to-hydrogen mass ratio of 8.0 illustrates the law of conservation of mass.

Answer 6

False

Question 7

T/F: The ratio in a chemical formula is a ratio of atoms, not a ratio of masses.

Answer 7

False

Question 8

T/F: The subscripts in a chemical formula represent the relative mass of each atom in a chemical compound.

Answer 8

False

Question 9

T/F: The subscripts in a chemical formula do not change for a given compound.

Answer 9

True

Question 10

T/F: Chemical formulas normally list the most metallic elements first.

Answer 10

True

Question 11

T/F: The formula of a compound comprised of two nitrogen atoms and one oxygen atom should be written properly as ON₂.

Answer 11

False

Question 12

T/F: Molecular elements do not exist in nature.

Answer 12

False

Question 13

T/F: The element nitrogen normally exists in nature as a diatomic molecule.

Answer 13

True

Question 14

T/F: If a chemical reaction produces the molecular element oxygen, the formula of oxygen should be written as O₂.

Answer 14

True

Question 15

T/F: Carbon dioxide is an example of a molecular compound.

Answer 15

True

Question 16

T/F: The basic unit of an ionic compound is called the formula unit.

Answer 16

True

Question 17

T/F: SO₂ is an ionic compound.

Answer 17

False

Question 18

T/F: Ionic compounds have a net charge of zero.

Answer 18

True

Question 19

T/F: Ionic compounds always contain positive and negative ions.

Answer 19

True

Question 20

T/F: In ionic compounds, the net positive charge always equals the net negative charge.

Answer 20

True

Question 21

T/F: The ionic compound that forms between aluminum and oxygen is AlO.

Answer 21

True

Question 22

T/F: The ionic compound that forms between Mg and O is MgO.

Answer 22

True

Question 23

T/F: The correct formula for calcium fluoride is CaF₃.

Answer 23

False

Question 24

T/F: Ionic compounds are usually made up of a metal and a nonmetal.

Answer 24

True

Question 25

T/F: The ionic compound MgO is named manganese oxide.

Answer 25

False

Question 26

T/F: The name of KNO₃ is potassium nitratide.

Answer 26

False

Question 27

T/F: The correct formula for sodium permanganate is NaMgO₄.

Answer 27

False

Question 28

T/F: When elements combine to form compounds, their properties change completely.

Answer 28

True

Question 29

The first chemist to formally state the law of constant composition was:

Answer 29

Joseph Proust

Question 30

The law of constant composition states:

Answer 30

All samples of a given compound have the same proportions of their constituent elements.

Question 31

The oxygen-to-hydrogen mass ratio of water is always 8.0 is an example of what fundamental law?

Answer 31

Law of Constant Composition