Matter, Change and Energy

Review

Physical Change

• A change that DOES NOT change the chemical compostion of a substance.

• Examples: melting (and all phase changes), tearing or breaking.

States of Matter• Solid – slower moving particles, strong

attractions, definite volume and shape.

• Liquid – particles move faster than solids, moderate intermolecular attractions, definite volume, no definite shape.

• Gas – rapidly moving particles, almost no intermolecular attractions, no definite volume, no definite shape.

Changes of States of Matter

Enthalpy- total energy of a system (often mostly in the form of heat).

Remember: A change of state is a physical change.

Solid, liquid, or gas?

Solid Liquid Gas

Chemical Changes• Are also known as chemical reactions.• Involve energy.• Make a new substance by rearranging atoms.• Are not easily reversed.• Are expressed in a chemical equation:

Signs of Chemical Change• Uses or release heat or

light or other forms of energy

• Changes color• Effuses gas (bubbles)• Forms a precipitant (a not

soluble solid)• Odor changes

Classification of Matter

General

Specific Order ----------------------------------------------------Disorder

Matter

Homogeneous Heterogeneous

PureSubstance

Homogeneous Mixture

Heterogeneous Mixture

Elem

ent

Com

poun

d

Solution Mixture

Symbol

Elements• One kind of matter (one kind of atom).

Compounds• Two or more different elements chemically

combined in a fixed ratio.• Elements have different properties together,

than separate.

Compounds: The Laws of Definite and Multiple Proportions

• Law of Definite Proportions: The ratios of elements in compounds do not change.

• Law of Multiple Proportions: If you change the ratio of elements, it is no longer the same compound.

• Example: H2O is water

H2O2 is hydrogen peroxide

They are very different!

Allotropes• Allotrope: Compounds made of a single

element.

Allotropes:

Not Allotropes:

Carbon Allotropes:

Heterogeneous: Simple Mixtures• Any two things together with the parts visible.• Can be separated easily.

HomogeneousHeterogeneous

Separating Mixtures

• Filtering• Decanting• Boiling or Distilling• Magnets

Homogeneous Mixtures: Solutions• When one substance dissolves (disappears)

in another because the atoms or ions separate.

• Are transparent, but may be clear or colored.

• Two parts: Solute (disappears) and Solvent.

Heterogeneous mixtures: Suspensions

• Appears homogeneous, but eventually settles or separates.

• Are cloudy

Hetero- or Homogeneous mixture? Colloids

• A permanent suspension because the particles are so tiny.

• Are cloudy• Often have a Tyndall Effect.

Introduction to the Periodic Table

The End