8th Grade Chemistry

Matter

anything that takes up space and has mass

Proton

positively charged subatomic particle

Neutron

A subatomic particle that has no charge

Electron

a negatively charged subatomic particle

Nucleus

Center of an atom

atomic mass

Number of protons and neutrons in an atom

atomic number

the number of protons in an atom

valence electrons

Electrons on the outermost energy level of an atom

Ion

An atom or group of atoms that has a positive or negative charge.

Cation

an atom with more protons than electrons. positively charged

Anion

an atom with more electrons than protons. negatively charged

Element

A pure substance made of only one kind of atom

Compound

something made up of two or more elements

Solubility

The ability to dissolve in another substance

Solute

Substance being dissolved

Solvent

substance doing the dissolving

Saturated

A solution that contains the maximum amount of dissolved solute in a concentration.

Supersaturated

A solution that contains more than the maximum amount of dissolved solute in a concentration.

Unsaturated

A solution that contains less than the maximum amount of dissolved solute in a concentration.

Law of Conservation of Matter

matter cannot be created or destroyed

closed system

matter is not allowed to enter or leave, has a lid

open system

matter can enter and leave, no lid

Decomposition

A substance that breaks down into two or more simpler substances

Synthesis

two substances combine to make a more complex substance

AB->A+B

Decomposition formula

A+B->AB

synthesis formula

single displacement

one element replaces another in a compound

double displacement

two ionic compounds react and the ions switch partners

AB+C->AC+B

single displacement formula

AB+CD->AC+BD

double displacement formula

Combustion

a substance reacts with oxygen to create water, carbon dioxide, and a large amount of heat or light

AB+O2->CO2+H2O+Energy

Combustion formula

catalyst

substance that speeds up the rate of a chemical reaction

collision theory

states that particles must collide in order to react