Chp 2. MATTER & MATERIALS

2.1 Chemistry

A branch of science that deals with the composition, structure, properties and reactions (transformations) of matter.

2.1 DESCRIPTION OF MATTER

Substances that are visible and invisible

(anything that has mass and occupies space)

Substances that are living and nonliving

2.1 Matter doesn’t include energy, in its various forms

(E.g., heat, light, electricity)

All transformations of matter involve energy changes. Chemist are interested in the energy changes that occur when matter is transformed.

MATTERCan it be physically

separated?

MIXTUREPURE SUBSTANCE

yesno

2.2 Pure Substance (Substance)

Matter that cannot be separated into other kinds of matter using physical means.

Examples

Sugar, ammonia, water, and oxygen.

It has a fixed composition and distinct properties.

2.2 Mixtures

Matter containing 2 or more substances in which each substance retains its own identity.

Separable into individual substances by physical means.

Mixtures can exist in any combination of pure substances. Therefore the composition of a mixture is variable.

MATTERCan it be physically

separated?

MIXTUREPURE SUBSTANCE

yes no

1. Only one substance present

2. Definite and constant composition

3. Properties are always same under given set of conditions

1. Physical combination of two or more substances

2. Variable composition

3. Properties vary as composition varies

4. Components can be separated by physical means

2.10 PHYSICAL SEPARATION METHODS Use physical properties and changes to

separate mixtures. Melting point (freezing point) Boiling point (condensation point) Water solubility (dissolving) Density

Techniques include: Distillation Filtration Magnetism Floatation

2.2 Mixture subclassifications

Heterogeneous

Homogeneous

Homogeneous Mixture

(solution)

Heterogeneous Mixture

MIXTURE

Is the composition uniform?

noyes

These are physical classifications based on observation of the matter

MATTERCan it be physically

separated?

PURE SUBSTANCE

yesno

A mixture is a variable combination of 2 or more pure substances.

HeterogeneousHomogeneous

Homogeneous (solution) One visibly distinguishable

phase (uniform appearance) Uniform properties

throughout the phase particles don’t settle EX: rubbing alcohol

Heterogeneous Observe two or more

visible phases Each phase has

different properties particles settle EX: fresh-squeezed

lemonade

MATTERCan it be physically

separated?

Can it be chemically decomposed?

CompoundElement

PURE SUBSTANCE

no

no yes

Homogeneous Mixture

(solution)

Heterogeneous Mixture

MIXTURE

yes

Is the composition uniform?

noyes

2.2 Pure Substances

Element composed of identical atoms Cannot be broken down into

simpler substances using chemical methods

EX: copper wire, aluminum foil

2.2 Pure Substances

COMPOUND composed of 2 or more

elements in a fixed ratio properties differ from those of

individual elements Cannot be separated by

physical means Separated by chemical means EX: table salt (NaCl)

Substances and Mixtures Examples:

Graphite (all C atoms)

pepper

sugar (sucrose)

paint

gasoline