Ch. 2

Matter and Change

Matter

• Anything that has mass and takes up space

• Mass– Amount of matter the object contains

Substances

• Matter that is uniform and has a definite composition (Pure Substances)

• Is sugar a pure substance?– Yes—100% sucrose

• Is lemonade a pure substance?

Physical Properties

• Quality or condition of a substance that can be observed or measured without changing the substance’s composition

• What are some?– Color, solubility, odor, hardness,

density, melting point, boiling point

States of Matter

• Solids– Matter that has definite shape and volume

• Liquids– Form of matter that flows, has a fixed volume, and

takes the shape of its container

• Gases– Form of matter that takes both the shape and volume

of its container– Vapor—Gaseous state of a substance that is normally

a solid or liquid (not interchangeable with the term gas)

Physical Changes

• A change which alters the material without altering the chemical composition of it– Melting of ice– Freezing of water– Water to steam– Etc etc

Mixtures

• Physical blend of two or more substances

• Like a salad!

• Heterogeneous mixtures– Not uniform in composition

• Homogeneous mixtures– Completely uniform composition

• Salt Water

Solutions

• Special name for a homogeneous mixture

• Solutions may be liquids, solids, or gases

Separating Mixtures

• Distillation– A liquid is boiled to produce a

vapor that is then condensed again to a liquid

– Tap Water

Elements

• Elements– Simplest forms of matter that can exist

under normal laboratory conditions– Cannot be separated into simpler

substances– Oxygen, Hydrogen, Carbon

Compounds

• Two or more elements that combine together

• They CAN be separated into simpler substances by chemical means

• Water– Hydrogen and oxygen

• Table Salt– Sodium chloride

Chemical Symbols

• Represent individual elements

• Provide a shorthand way of writing the chemical formulas

• C12 HH2222OO1111

Chemical Reactions

• One or more substances change into new substances

• Reactants– Starting substances

• Products– Substances formed

Ex: Iron + Oxygen Iron Oxide (Rust)

Chemical Properties

• Ability of a substance to undergo a chemical reaction and to form new substances

• Rusting is a chemical property of iron

• Observed when a substance undergoes a chemical change

Law of Conservation of Mass

• In any physical change or chemical reaction, mass is neither created nor destroyed…..it is conserved