phases of matter - chp. 15 pp. 363-379 easiest way to describe matter solid- definite volume and...

Phases of Matter - Chp. 15 pp. 363-379

Easiest way to describe matter

• Solid- definite volume and shape

• Liquid-definite volume and indefinite shape

• Gas-indefinite volume and indefinite shape

Submicroscopic level - (can’t see even with a microscope)

• Solid-attractions between atoms and molecules are strong

• enough to hold them in a fixed position.

Water- (snowflake)

Submicroscopic level - (can’t see)

• Liquid- molecules slip past one another like marbles in a bag

Submicroscopic level

(CAN’T SEE)• Gas- molecules bounce off one another

Physical and Chemical Properties

• Physical properties-describe the physical attributes of a substance

– color

– Hardness

– Specific Heat Capacity- the heat required to change the temp. of a unit mass of a substance by 1 (how fast things heat up)

• EX. Gold- yellowish, soft, dense at room temperature.

– density

– texture

– phase (solid, liquid or gas)

Surface Tension• Caused by the attraction between

molecules.

Which one?

Physical change-• Physical change- change in some physical

property of a substance

– Ex. Melting Ice, boiling water, freezing water

– All substances are still water (It maintains it’s chemical identity)

Gas PhaseLiquid PhaseSolid Phase

• Evaporation-

Liquid to gas

• Sublimation-

solid to gas

• Condensation-

gas to liquid

• Melting-

solid to liquid

• Freezing-

liquid to solid

Phase Changes-

(Vaporizing)

Endothermic-absorb heat• Melting

• Boiling

• Sublimation

Exothermic-release heat

• Freezing

• Condensation(Vaporizing)

Endothermic-absorb heat

Exothermic-give off heat

Chemical change- atoms rearrange and switch partners

– Iron atoms break apart and combine with oxygen atoms

– Ex. Iron Rust

– Ex: Grape juice Wine

– Sugar molecules rearrange to make alcohol molecules.

Chemical properties- the tendency of a substance to transform into another substance

Fe Fe

Fe

O

O

O

Chemical change

• Chemical change means there is a new chemical

• Physical change means there are just new attributes

• Hard to tell the difference because there is a change in appearance for both changes in many cases.

Elements,

Compounds

and Mixtures

H2

H2O

H2O + NaCl

Element- consisting of only one type of atom

• 118 elemental materials

• 90 naturally occurring elements

EX: H, O, C, B, He, O2, H2,

Compound- atoms of different elements attached to one another

EX: Sodium (Na) atoms & Chlorine (Cl) atoms

Sodium chloride (NaCl) =

Table Salt

Chemical Formula- represents a compound

• EX:

• NaCl – Sodium Chloride – “salt”

• H2O – dihydrogen monoxide

• H2O2 – ?

• MnO2 – ?

dihydrogen dioxide

Manganese dioxide

Mixtures- elements and compounds, compounds and compounds or mixture of elements

• Sea Water = mixture of H2O and a variety of salts

• Air = Mixture of N2, O2, and other gases

– Can separate mixtures by knowing the physical properties of the mixtures’ components.

• Boiling pts.

• Melting pts.

• Color…