Introduction to Chemistry What Matters? Chapters 2 & 3

SI Units Length – meter Mass – kilogram Time – second Temperature – Kelvin Quantity of Matter – mole Volume - liter

Commonly Used Prefixes Centi-1/100 or 0.01 Kilo-1000 or 1.0 x 10 3 Milli-1/1000 or 0.001

Matter Def- anything that has mass and occupies space 3 States of matter –Solid –Liquid –Gas

Phase Changes Melting Freezing Vaporization/Evaporation Condensing Sublimation Deposition

Changes of State

Melting/Freezing Energy must be ADDED for a substance to melt Energy must be REMOVED for a substance to freeze

Vaporization & Condensation Energy must be ADDED for a substance to boil Energy must be REMOVED for a substance to condense

Deposition/Sublimation Energy must be added for a substance to sublime Energy must be removed for a substance to undergo deposition

Law of Conservation of Energy Energy cannot be created or destroyed Energy of a reaction MUST be conserved

Elements, Compounds & Mixtures

Elements An element is matter in its simplest form Cannot be broken down by chemical means Periodic Table (114 elements)

Compounds Are combinations of elements Have the same composition Can be broken down by chemical means

Mixtures Have variable composition Can be separated physically or chemically Homogeneous Mixtures – are the same throughout Heterogeneous Mixtures – have different regions

Law of Conservation of Matter Matter cannot be created or destroyed Mass of a chemical reaction MUST be conserved

Separatory Techniques

Filtration Used for separating undissolved solids Pour through a mesh (filter paper)

Distillation Used to separate dissolved solids or liquid mixtures Uses physical changes

Chromatography Uses chemicals to separate the pigments of plant or chemicals Various Methods –Gas chromatography –Liquid chromatography –Thin-layer chromatography –Ion-exchange chromatography

Chemical vs Physical

Physical Properties A set of characteristics unique to a substance Odor Color Volume State Density Boiling point Melting point

Chemical Properties The ability of a substance to form new substances Wood burning Iron rusting Digestion photosynthesis

Physical Change Does NOT change the identity of the substance Composition remains the same

Chemical Change Changes the composition of the substance Has new physical properties that differ from the original