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