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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 103
• 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