Molecules and Ions

Question 1

What is a molecule?

Answer 1

aggregate of at least two atoms in a definite arrangement held together by chemical forces, aka, two or more atoms joined by a chemical bond.

Question 2

What is a diatomic/polyatomic molecule?

Answer 2

Diatomic molecule: contains only two atoms

Polyatomic molecules: more than two atoms

Question 3

What is an ion? Cation? Anion?

Answer 3

1. Ion: an atom or group of atoms that has a net positive or negative charge
2. Cation: loss of one or more electrons from a neutral atom = an atom with a net positive charge
3. Anion: ion with negative net charge due to an increase in electrons

Question 4

What is a chemical formula and molecular formula?

Answer 4

1. Chemical formulas: express the composition of molecules and ionic compounds in terms of chemical symbols
2. Molecular formula: exact number of atoms of each element in the smallest unit of a substance

Question 5

What is the empirical formula? Molecular formula?

Answer 5

Tells us which elements are present and the simplest whole-number ratio of their atoms. A molecular formula will be the empirical formula times 1 or times 2 or times 3, etc.