Phases of Matter - Chp. 15 pp 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 Phase Liquid Phase Solid 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 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 H2H2 H2OH2O H 2 O + NaCl

Element- consisting of only one type of atom 118 elemental materials 90 naturally occurring elements EX: H, O, C, B, He, O 2, H 2,

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” H 2 O – dihydrogen monoxide H 2 O 2 – ? MnO 2 – ? dihydrogen dioxide Manganese dioxide

Mixtures- elements and compounds, compounds and compounds or mixture of elements Sea Water = mixture of H 2 O and a variety of salts Air = Mixture of N 2, O 2, and other gases –Can separate mixtures by knowing the physical properties of the mixtures’ components. Boiling pts. Melting pts. Color…