Chapter 2: Matter and Change

Matter Anything that has mass and takes up space

Mass The amount of matter an object has Units: Grams Measuring tools: Triple Beam Balance, Electronic scale, Analytical Scale

Pure Substance Contain only one kind of matter Have identical physical properties

Physical Properties A quality or condition that can be observed or measured without changing the substances composition Color, solubility, odor, hardness, density, melting point, boiling point

States of Matter

Solid Definite shape AND volume Incompressible Particles are packed tightly together

Liquid Definite volume Takes the shape of its container Almost incompressible-particles not rigidly packed

Gas Takes the volume and the shape of its container Particles in a gas are spaced far apart Easily compressed

Vapor The gaseous state of a substance that is generally a solid or a liquid at room temperature

Physical Change Changes the material without changing the composition Boiling, freezing, dissolving, melting, condensing, breaking, splitting, cracking, cutting, crushing, bending……… Usually reversible

Mixture A physical blend of 2 substances Compositions may vary

2 Types of Mixtures Heterogeneous Mixtures Homogeneous Mixtures

Heterogeneous Mixture One that is NOT uniform in composition

Homogeneous Mixture The same throughout

Solution A homogeneous mixture Solutions may be solids, liquids, or gases Same composition throughout

Phase Any part of a system with uniform composition and properties

Separation of Mixtures Distillation

Separation of Mixtures Centrifuge

Separation of Mixtures

Elements The simplest forms of matter that can exist under laboratory condition Can not be separated into simpler substances by chemical means The building blocks for all other substances

Chemical Symbol One or 2 letters The first letter is always capitalized

+ = Compounds Sodium Metal Sodium Chloride Chlorine Gas 2 or more elements chemically combined Can be separated into simpler substances by chemical means + = Sodium Metal Sodium Chloride Chlorine Gas

Compounds The subscript numbers in chemical formulas represent the proportions of elements that make up the compounds Pb2(SO4)3 Pb (lead)  2 S(Sulfur) 3 Oxygen  12

Chemical Reaction One or more substances change into new substances 2 H2 (g) + O2 (g)  2 H2O (g) Reactants Products

Chemical Property The ability of a substance to undergo a chemical reaction to form a new substance I.e. flammability, alkalinity, acidity, rusting Chemical properties are only observed when a substance undergoes a chemical change

Chemical Reactions (rust-oxidation)

Chemical Reactions (combustion)

Chemical Reactions (acid/base)

Indicators of a Chemical Reaction Energy is absorbed or given off (change in temperature) Change in color Change in odor Formation of a solid (precipitation) Formation of a gas

Law of Conservation of Mass Mass is neither created nor destroyed  mass of reactants = mass of products