Understanding Physical and Chemical Properties and Changes

physical property

A property of matter one can observe or measure without changing its identity.

chemical property

A property of matter one can observe about how it interacts with other substances.

physical change

A change where no new substances are produced.

chemical change

A change where new substances are produced.

chemical reaction

Another name for a chemical change.

signs of a chemical change

a. change in energy, b. change in color, c. formation of a gas, d. formation of a solid.

chemical equations

Reactions can be written as.

chemical formulas and symbols

A chemical equation uses what to summarize a reaction?

reactants

Substances at the start of the reaction.

products

Substances formed at the end of a reaction.

arrow in a chemical equation

means yields or produces.

balanced chemical equation

The number of reactant atoms must be equal to the number of product atoms.

law of conservation of mass

The total mass of the reactant atoms must equal the total mass of the product items.

synthesis

When two or more elements or compounds combine to make a more complex substance.

format of synthesis

A + B -> AB.

decomposition

When one substance breaks down into two or more simpler substances.

format of decomposition

AB -> A + B.

combustion

When fuel reacts with oxygen to produce carbon dioxide and water and release energy.

format of combustion

CxHy + O2 -> CO2 + H20.

single replacement

When one element replaces another element in a chemical compound.

format of single replacement

A + BC -> AC + B.

double replacement

When the positive ion on one compound replaces the positive ion of another.

format of double replacement

AB + CD -> AD + CB.