1-1 What is Chemistry?

• The study of the structures and properties of matter

• What are chemicals?

• Where can chemicals be found?

CHEMICAL

• Any substance with a definite composition

• Chemicals can be found everywhere.

Everyone uses chemicals.• cooks• photographers• consumers• farmers• students• painters

The production of chemical compounds is a major industry.

All matter is made of particles.

• type and arrangement of particles determine its properties

• PHYSICAL STATE – the form matter takes as a result of the arrangement of its particles• Basic property of matter

The 3 most common states of matter on earth:

• SOLIDS – have fixed volume and shape• - particles are held tightly in a rigid structure • - vibrate slightly

• LIQUIDS – have fixed volume but variable shape• - particles are not held in rigid structure

• - can move past ea. Other

The 3 most common states of matter on earth:

• GASES – have neither fixed shape nor fixed volume• particles spread out to fill their container• free to move about independently

MICROSCOPIC

• refers to objects about the size of atoms

MACROSCOPIC

• refers to objects large enough to see w/ unaided eye

Physical Changes

• A change in which the identity of a subst. does not change• Change of state, breaking, heating, dissolving,

etc.

Compounds are made by CHEMICAL REACTIONS

• the processes by which elements and/or compounds interact w/ one another to form new substances.

• Also called chemical changes

• A rearrangement of the atoms that make up the reactant(s).

When butane burns, it reacts w/ oxygen in the air

- can be described by a word equation:butane + oxygen carbon dioxide + water

Butane and oxygen are REACTANTS

• a chemical that is present at the beginning of a chemical reaction and that takes part in the reaction.• the starting materials in a reaction

Carbon dioxide and water are PRODUCTS

• chemicals produced as a result of a chemical reaction

Arrow separates the reactants and products and indicates the

direction the reaction proceeds.• Always points to the products.

• usually points to the right

Some reactions involve one reactant which decomposes into 2

or more products:

mercury (II) oxide mercury + oxygen

• decomposition reaction

Evidence of chemical change:

• Evolution of a gas

• Formation of a PRECIPITATE – an insoluble solid formed from a solution

• Evolution or absorption of heat

• Emission of light

• Color change in the reaction system