CHAPTER 2 MATTER AND CHANGE:

2.1 PROPERTIES OF MATTER Describe matter by looking! a.Extensive Properties – depends on the amount of matter in a sample examples- volume and mass b. Intensive Properties – depends on the type of matter in a sample example – bowling ball

Identifying Substances: Substance: matter that has a uniform and definite composition Physical property: the quality of a sample that can be observed or measured without changing the substance’s composition. Hardness Color Malleability Conductivity Ductile

STATES OF MATTER Solid – definite shape definite volume – atoms vibrate in fixed position Liquid – indefinite shape definite volume – atoms are in close contact but not rigid Gas – takes shape and volume of container – atoms are active and far apart As energy in the substance increases the atoms motion increases! What is the difference between gas and vapor?

PHYSICAL CHANGES Properties of a material change but the composition remains the same. Freeze Melt Condense Break Split Grind Evaporate Sublimate How can physical changes be reversible or irreversible?

2.2 MIXTURES Mixture – a physical blend of two or more substances Heterogeneous – uneven mixture composition Homogeneous – even mixture composition What is a phase?

SEPERATING MIXTURES Filtration Distillation Magnetism

2.3 ELEMENTS AND COMPOUNDS Element – simplest form of matter and cannot be broken down into simpler substances. Compound – a substance that contains two or more elements chemically combined in a fixed proportion and it can be broken down into simpler substances by chemical means

Chemical Change: If a substance takes on new properties from the combination or separation of element in the substance Heat is a good catalyst – what is a catalyst? What might give you a clue a chemical change has occurred?

SYMBOLS AND FORMULAS Symbols – one or two letters used to identify an element Formulas – a shorthand way to identify a compound or molecule

CONSERVATION OF MASS The mass of the product always equals the mass of the reactants so in any physical or chemical change mass is conserved.

Chemical Reactions: Key Concepts 1.What always happens during a chemical change? 2.What are the four possible clues that a chemical change has taken place? 3.How are the mass of the reactants and the mass of the products of a chemical reaction related? Vocabulary: Chemical property Chemical reaction Reactant Product Precipitate Law of Conservation of Mass

Chemical Changes: Chemical changes occur when the composition of matter changes. Examples – Burn, Rust, Rot, Decompose, Ferment, Explode, Corrode, Odor Chemical properties of matter allow how the matter will change. - these properties are tied to their position on the periodic table - some properties create change faster - properties exhibited during a reaction help identify matter - chemical properties do not remain the same after a chemical reaction. - not easily reversed

A Chemical Change = A Chemical Reaction A chemical reaction contains two parts 1. The Reactant – the matter before the reaction 2. The Product – the matter transformed by the reaction - Looking at page 53 give me an example of reactant and product.

Recognizing Chemical Change There are several guidelines to help you identify a chemical reaction. - Color change - Transfer of energy (cold or hot) - Production of gas - Formation of precipitate -Using page 54 give me some examples of recognizable chemical changes. Can you think of any others that might occur in your daily life?

Conservation Of Mass The Law of conservation of mass that in any physical or chemical change mass is conserved. That means that matter can not be created or destroyed. The matter either retains its chemical properties or they the matter is arranged to exhibit new properties.