Balance1.

2.

3.

1. What is a chemical formula?2. View examples of chemical formulas.3. What is a coefficient?4. What is a subscript?5. Differentiate between a subscript and a coefficient in

a chemical formula.6. Identify reactants and products in a chemical

equation?7. Identify and count the number of atoms in a chemical

equation.8. Define the law of conservation of mass.9. Observe examples balanced chemical equations.10. Balance chemical equations.

What are chemical symbols?

Chemical symbols are representations of elements on the periodic table.

What are chemical formulas?

A chemical formula shows the elements that make up the

compound and the number of atoms of each element in that compound.

Examples of chemical formulas.

CO2

H2O

CO

H3ONaCl

H2O

H is the symbol for Hydrogen

O is the symbol for Oxygen

The subscript means the molecule of water has two atoms of hydrogen

No subscript after oxygen means the molecule of water has only one atom of oxygen.

Chemical Formula

Coefficient

H2O3

Molecule of Water

The coefficient shows the number of molecules of the compound.

Coefficient & Subscript

Identify the coefficient and or subscript.

CO2

H2O

2MgO2 2KOH

3AgNO32AgNO3

1.

2.

3.

4.

5.

6.

What is a chemical equation?

A chemical equation is a representation of a chemical reaction on paper.

Examples of chemical equations.

2H2 + O2 2H2O

CaO + H2O Ca(OH)2

C + O2 CO2

Reactants & Products

Chemical equations area split up into two parts:

Reactants-the starting materials on the left side of the arrow

Products-the new substance or substances produced on the right side of the arrow.

Reactants Products

Parts of a Chemical Equation

C+O2 CO2

REACTANTS are the starting

materials on the left side of

the arrow.

PRODUCT is the new

substance or substances

produced and are on the right

side of the arrow.

yieldsor

produces

Reactants & Products

Identify the reactants and products.

1. CH4 + O2 CO2 + 2H2O

2. 3H2 + N2 2NH3

3. 2H2 + O2 2H2O

4. CaO + H2O Ca(OH)2

Count the atoms

Count the number of atoms in the chemical equation.

C + O2 CO2

How many carbon (C) atoms on each side?

How many oxygen (O) atoms on each side?

Count the atoms

Count the number of atoms in the chemical equation.

3H2 + N2 2NH3

How many hydrogen (H) atoms on each side?

How many Nitrogen (N) atoms on each side?

Count the atoms

Count the number of atoms in the chemical equation.

2H2 + O2 2H2O

How many hydrogen (H) atoms on each side?

How many carbon (C) atoms on each side?

Count the atoms

Count the number of atoms in the chemical equation.

2Mg + O2 2MgO

How many magnesium (Mg) atoms on each side?

How many oxygen (O) atoms on each side?

Count the atoms

Identify and count the number of atoms in the chemical equations.

1. CH4 + 2O2 CO2 + 2H2O

2. 4Al + 3O2 2Al2O3

3. 2K + 2H2O 2KOH + H2

ALL CHEMICAL EQUATIONS MUST BE BALANCED ! ! !

Law of Conservation of Mass

Mass (atoms) cannot be created nor destroyed in a chemical reaction.

What does that mean for us?

There must be the same number and kinds of atoms on each side of the chemical equation.

10 atoms of O

P P4O10O2+4 5

4 atoms of P 4 atoms of P

10 atoms of O

=

balanced

H + O2 H2OH =1 atom

O =2 atoms

H =2 atoms

O =1 atom

=

H + O2 H2O2

O =2 atomsO =2 atoms

H =4 atoms

4H =4 atom =

Mg + O2 MgO

Mg = Mg =

O = O =

11

2 1

2

2

2

2

2

Ca + O2 CaO

Ca = Ca =

O = O =

11

2 1

2

2

2

2

2

N2 + H2 NH3

N = N =

H = H =

12

2 3

2

6

2

3

6

Cu2O + C Cu+ CO2

Cu = Cu =

O = O =

C = C =

12

1 2

4

2

4 4

2

1 1

H2O2 H2O + O2

H = H =

O = O =

22

2 3

2

4

4

2

4

4

Balance the equations

1. Mg + O2 MgO

2. H2 + N2 NH3

3. CH4 + O2 CO2+

H20

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