Chemical Formulas and Equations

Test Review

H2O 2H2 + O2 2H2O

Which is an example of a compound?

NaCL A compound has…..

2 or more atoms AND they need to be different.

Na2NaNaClNa₂

Which is not a molecule?

Na Na is just an element (1 atom).

Molecules have 2 or more atoms.

H₂ONaClNaNa₂

How many atoms are in Na₂SO₄?

7

Na = 2S = 1O = 4

How many atoms are in C6H12O6?

24

Na = 6S = 12O = 6

Which is an example of a element?

O O is just an element (1 atom).

H₂OSO₄C₆H12O₆

A molecule has 3 atoms of hydrogen (H)

and 2 atoms of sulfur (S), what’s the formula?

H₃S₂

Four molecules of 2 atoms of hydrogen (H) and

2 atoms of oxygen (O), what’s the formula?

4H₂O₂

How many atoms are in 2CaCl₂?

6

Ca = 2Cl = 4

What’s the ratio of calcium (Ca) to chlorine (Cl) in CaCl₂?

1 to 2

Ca = 1 Cl = 2

What’s the ratio of oxygen(O) to hydrogen (H) in H₂O?

1 to 2

O = 1 H = 2

What’s the ratio of oxygen (O) to sulfur (S) in 2SO₄?

8 to 2

2S1O4

O = 8 S = 2

What is the formula for the model below.

4H₂O₂

= Hydrogen = Oxygen

The coefficient in 7H2CO3 tells that there is…

7 molecules of H2CO3

The coefficient in 6LiNO3 tells that there is…

6 molecules of LiNO3

What’s the ratio of lithium (Li) to oxygen (O) in 3LiNO3?

3 to 9

3Li1N1O₃

Li = 3 O = 9

What’s the coefficient of 4MgCl₂?

4The coefficient is the big number in front of the

chemical formula.

It tells the number of molecules there are.

What is the subscript(s) of 4MgCl₂?

2The subscripts is the small number behind the chemical

symbol.

It tells the number of atoms there are for that element.

What’s the ratio of hydrogen (H) to zinc (Zn) in 2ZnH₂?

4 to 2

2Zn1H2

H = 4 Zn = 2

What is the subscript(s) of 7Ba₃P₂?

3 and 2The subscripts is the small number behind the chemical

symbol.

It tells the number of atoms there are for that element.

What is the formula for the model below.

3FeH₃

= Iron (Fe) = Hydrogen (H)

What does the subscript tell you?

The number of atoms of that element.

What is the Law of Conservation of Mass?

Mass cannot be lost or gained OR

Mass cannot be created or destroyed.

What are the product(s)?

2H2O2 → 2H2O + O2

The yield sign always points to the product.

What are the product(s)?

3Ca + N2 → Ca3N2

The yield sign always points to the product.

What are the reactant(s)?

2Li + F2 → 2LiF

The yield sign always points to the product.

What are the reactant(s)?

Al2O3 4Al + 3O2

The yield sign always points to the product.

What are the product(s)?

2NaOH + H2 2Na + 2H2O

The yield sign always points to the product.

Does this chemical equation follow the Law of Conservation

of Mass?

Al + S → Al2S3 No1 = Al = 2 (Not Equal)

1 = S = 3 (Not Equal)

Does this chemical equation follow the Law of Conservation

of Mass?

HgO → Hg + O2 No1 = Hg = 1 (Equal)1 = O = 2 (Not Equal)

Does this chemical equation follow the Law of Conservation

of Mass?

2K + S → K2S Yes2 = K = 2 (Equal)1 = S = 1 (Equal)