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…