Chem Unit 2

Matter

any substance that has mass and volume

Particle diagrams

a visual model that uses shapes to represent matter at the atomic or molecular level

can be used to show states of matter, composition of matter, or changes (chemical reactions)

Particle

general term for a piece of matter (atom, molecule, etc.)

4 states of matter (3 common)

Solid, liquid, gas, plasma

Solid

Definite shape and volume. Particles may vibrate, but do not move past each other

Liquid

Definite volume but no definite shape. Particle flow past each other

Gas

No definite shape or volume. Particles move rapidly and randomly, colliding with each other. Gas expands to fill any area it is in.

Matter can be described by

its properties

Every substance has

characteristic properties

Physical properties

Characteristics of a substances that can be observed or measured without changing the substance

Chemical properties

Characteristics that describe how a substance reacts or changes into a different substance

Extensive properties

Change depending on the size or amount of matter

Pertains to physical properties

Intensive properties

Do not depend on the amount of matter present

Pertains to physical properties

Extensive ex:

mass, volume, length, moles

Intensive ex:

color, odor, boiling pt., melting pt., density, solubility, hardness, malleability, ductility, conductivity

If you divide one extensive property by another, you get an _______ property

intensive

because the ratio of the two extensive stays constant- they change with one another at the same rate

Density =

mass/volume

Chemical properties ex:

flammability, reactivity, toxicity

Flammability

ability of a substance to burn

Reactivity

the tendency of a substance to undergo a chemical reaction with a specific substance or under chemical conditions

Toxicity

the degree to which a substance can chemically harm an organism

Common signs something is undergoing a chemical reaction

forms gas (bubbles), forms precipitates/solids, color change, temp. change, produce light or sound, odor change

Which kind of change cannot be reversed

chemical

Which kind of change can be reversed (mostly)

physical

Physical change ex:

phase change (change of state of matter), change in size, change in chape, dissolving (most of the time)

Chemical change ex:

decomposing, oxidizing, burning, tarnishing, rotting, metabolism

a chemical change can also be called a

chemical reaction

reactants are to the ____ of the arrow

left

products are to the ____ of the arrow

right

substances the react in a chemical change are the

reactants

substances produced by chemical changes are called

products

Law of Conservation of Mass

mass is never created or destroyed

In ANY chemical or physical process, matter might be transformed, but it is MASS is ALWAYS CONSERVED.

i.e. you can’t change the amount of stuff in the universe; you can only alter its properties.

Chemical reaction form substance with NEW

properties