Physical Properties
observed and measured without changing the chemical identity of a sample.
Physical properties examples
Luster, elasticity, color, mass
Chemical properties
observed and measured as a sample changes chemical identity.
Chemical properties properties
Flammability, Acidity, Reavactivity
Chemical reactions
energy must be SUPPLIED or ABSORBED to break chemical bonds of reactants. energy is released when new bonds are made.
Chemical change
Alter the chemical composition of the reactant
Chemical change example
Photosynthesis, burning wood, digestion
Sings of chemical changes
change in odor, color, light emission, temperature, and endothermic reactions.
The law of conservation of mass
matter is neither created nor destroyed by chemical reactioons or physical changes
You should use a closed system…
so that you can show that the mass before and after the reaction is the same
Synthesis
two or more substances combine to form a new compound ex-2Na+Cl*2——2NaCl
decomposition
a single compound is broken down into two or more smaller compounds ex-AB——A+B
single displacement
when one element replaces a similar element in a compound ex-AX+B——BX+A
Double displacement
ions from two compounds in a solution exchange positions to produce two new compounds ex-AB+CD——AD+CB
Combustion
The reaction of an element or compound (usually a hydrocarbon) with oxygen tyo form CO*2, water , and heat.
Endothermic Reaction
if more energy is ABSORBED than released
example of Endothermic Reaction
cooking pancakes
Exothermic reaction
if more energy is RELEASED than supplied
examples of Exothermic reaction
handwarmer
Balancing equations
a balanced equation should have an equal amount of atom on each side.