Chemistry

What is an atom?Atoms are the basic building blocks of ordinary

matter. Atoms can join together to form molecules, which in turn form most of the objects around you.

Atoms are composed of particles called protons, electrons and neutrons.

What is an element?An element is a substance that is

made entirely from one type of atom. If you change the number of protons an atom has, you change the

type of element it is.

Atoms and Elements

Metals

Metals  Metals are opaque, lustrous elements that are good conductors of heat and electricity. Most metals are malleable and ductile and are generaly denser than the other elemental substances.

Non-metalsA non-metal is an element on the

periodic table that does not have the properties of a metal element. Non metals are usually found as gases.

Non-metals

The periodic tableWhat is the periodic table?The periodic table arranges all the known elements in an informative array. Order generally coincides with increasing atomic mass.

compounds A chemical compound is a

substance composed of two or more

different elements

chemically bonded

together in a fixed

proportion by mass.

Chemical reactionsA chemical reaction is a process that leads to the transformation of one set of chemical substances to another.

Physical reactions

A common physical change

occurs when matter changes

from one phase to another.  When an ice cube melts for

example, it becomes liquid

water.