This document discusses the differences between physical and chemical changes. Physical changes involve changes in a substance's physical properties like state, color, or melting point but do not alter its chemical identity. Chemical changes produce new substances through the rearrangement of atoms and breaking/forming of bonds. Chemical reactions are represented through balanced chemical equations to show the reactants and products have the same number and type of atoms.

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 Color
 Melting Point
 Boiling Point
 Electrical Conductivity
 Specific Heat
 Density
 State (Solid, Liquid, Or Gas)


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 Changes In Physical Properties
 Melting
 Boiling
Condensation
No Change Occurs In The Identity Of The
. Substance
Example:
Ice , Rain, And Steam Are All Water

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 Atoms in the reactants are rearranged to
form one or more different substances
 Old bonds are broken; new bonds form
Examples:
 Fe and O2 form rust (Fe2O3)
 Ag and S form tarnish (Ag2S)

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A process in which at least one new
substance is produced as a result of
chemical change.

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Reactants Products

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Chemical symbols give a “before-and-after”
picture of a chemical reaction
Reactants Products
MgO + C CO + Mg
magnesium oxide to form carbon monoxide
reacts with carbon and magnesium

8. 4 NH3 + 5 O2 4 NO + 6 H2O
Four molecules of NH3 react with five molecules
O2 to produce four molecules NO and six
molecules of H2O
8
or
Four moles NH3 react with 5 moles O2 to produce
four moles NO and six moles H2O

9. Same numbers of each type of atom on each side
of the equation
9
Al + S Al2S3
2Al + 3S Al2S3 Balanced

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H2 + Cl2 2 HCl
+ +
Total atoms = Total atoms
2 H, 2 Cl 2H, 2 Cl
Total Mass = Total Mass
2(1.0) + 2(35.5) 2(36.5)
73.0 g = 73.0 g

11. In any ordinary chemical reaction, matter
is not created nor destroyed
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