Rules For Chemical Equations

Question 1

Name Rule for monatomic anions

Answer 1

(nonmetals and metalloids)

Remove last few letters of element name and replace with “-ide” suffix

Question 2

Empirical Formula

Answer 2

Chemical equation that shows the relative number of atoms of each type per molecule

• simplest whole number ratio
• as subscripts

Question 3

Molecular Formula

Answer 3

Chemical equation that shows the actual number of atoms of each type per molecule

• full number ratio
• as subscripts

Question 4

General Rules for writing formulas for ionic compounds

Answer 4

cations are listed first
anion listed second
the compound MUST be neutral (cations and anions must cancel out)

Question 5

Formula Weight (FW)

Answer 5

The sum of all atomic weights of all atoms in a formula (usually in amu’s)

Question 6

General Rule for interchanging between Molecular formula and empirical

Answer 6

molecular formula= (empirical formula)n (where n is a whole number integer)

In general- you can go from molecular to empirical, but not empirical to molecular

Question 7

% weight

Answer 7

For element X in compound A

((mol X/mol A) x (Mm of X))/ (Mm of A) x 100

Question 8

molecular compounds

Answer 8

nonmetals or metalloids + other nonmetals or metalloids

Question 9

Ionic comounds

Answer 9

metals of NH4+ with a) nonmetals or metalloids b) polyatomic anion

Question 10

Isotope’s Atomic Weight

Answer 10

AW of X= faMa + fbMb + fcMc….

where f is the fractional abundance and M is the mass of the isoptope