Unit+1+-+Basic+Laws+of+Chemistry

**__ Atomic Theory __**

-All matter is composed of small particles called atoms.

-Atoms cannot be created or destroyed by normal means.

-Atoms consist of a positively charged nucleus (Protons, Neutrons) with orbiting electrons.

-Atoms of a given element have identical properties

-Atoms of different elements have different properties.

-When two or more elements combine in a constant ratio, they form a new substance called a compound.

** __ Elements vs. Compounds __ ** Both of these terms refer to pure substances.

An element is a pure substance comprised of a single type of atom.

A compound is a pure substance that contains two or more elements in a fixed proportion.

When two or more elements they combine to create a compound or a molecule

When writing compounds, it will be written in symbols (found on the periodic table) and they are often followed by a small # representing the quantity of each atom.

N, O, F, Cl, Br, I and H are referred to as the special 7, as they can not exist in their own elemental state, they are called Diatomic.

__    **  Key Terms  **     __

Ion - Atom became charged by loss or gain of electrons

Ionic Compound - Comprised of positive ions (cation; Metals) and negative ions (anions; Non-metals)

Binary Ionic Compound - Comprised of two or more elements, 1 metal + 1 non-metal

Polyatomic Ions - Very hard to break apart, Definite charges must be Identified by chart or memory. For Some more useful sites, check out the following: [|Atomic Theory] [|Elements and Compounds] [|Key Terms]
 * [[image:http://www.corrosionsource.com/handbook/periodic/periodic_table.gif align="center" caption="Periodic Table"]] ||
 * Periodic Table ||