Unit 2 - Matter and Physical vs Chemical Properties and Changes

Matter

Anything that has and takes up space

• Made of atoms

  • Pure substance

Pure substance

Contains 1 type of atom

• Will be an element from periodic table

• Set chemical and physical properties

  • Ex: Gold

Pure substance single atom

Does not bond to any other atoms

• Ex: Helium 

Pure substance molecule

2 atoms combine to form a molecule

• An atom that bonds to another atom of the same element

  • Diatomic molecules (Diatoms)

Seven diatomic molecules mnemonic

"HONClBrIF" - H₂, N₂, F₂, O₂, I₂, Cl₂, Br₂

Allotrope

Substances from the same atom but arranged differently

• Ex: O₂

Compounds 

Two or more different elements joined by chemical bonds

• Fixed ratio

  • H₂O

• Cannot be separated physically, only chemically

Liquid to gas

Vaporization

Gas to liquid

Condensation

Gas to solid

Deposition

Solid to gas

Sublimation

Mixtures

Two or more pure substances that are not chemically bonded to each other

• Can be separated physically

• Does not have definite properties

  • Each substance retains chemical properties

Intermolecular forces

Physical forces which hold together substances

Homogeneous mixtures

Each substance is distributed evenly throughout the mixture

• Ex: Salt water

Heterogeneous mixtures

Substances are not distributed evenly throughout the mixture 

• Cereal and milk