Mixtures•A combination of two or more kinds of matter, each of which retain its own composition and properties.

•Heterogeneous mixtures-The composition of the mixture changes from place to place in it….its not uniform (chocolate chip cookie)•Homogeneous Mixtures- The composition of the mixture does not change from place to place in it…it is uniform (Kool-Aid)

•Solutions

Pure Substances•A homogeneous sample of matter that has the same composition and properties throughout.

•These cannot be broken down into other substances without changing its identity and properites.

Element• Are pure substances that cannot be broken

down into other substances by ordinary means.

• Entries on the periodic table are all elements.

Chemical Compounds• A pure substance that can be decomposed

into two or more simpler substances by an ordinary chemical change. By heating, reacting or dissolving. Not however,

by nuclear reaction.

Law of Definite proportions• A chemical compound contains the same

elements in the same proportion regardless of the size of the sample or the source of the compound. Water is always H2O Table salt is always NaCl

1. All matter is composed of extremely small particles called atoms

2. Atoms of a given element are identical in size, mass, and other properties; Atoms of different elements have different size, mass and other properties.

3. Atoms cannot be subdivided, created or destroyed.

4. Atoms of different elements can combine in simple, whole-number ratios to form chemical compounds.

5. In chemical reactions, atoms are combined, separated, or rearranged.

Parts Nucleus

Made of two particles Positive Proton

Has the same charge as an electron just opposite charged

Never leaves the nucleus An Atom of an element cannot gain or lose these, or

it will become another element Has a mass of 1.673x10 -24 grams

Neutron Has no charge Has a mass of 1.675x10-24 grams These do not leave the nucleus, but do not dictate

what element the atom is.

Outside the Nucleus Electrons

Negative charge Can be lost or gain

This does not change the element, but does change the charge of the atom, making it an ion.

Has much less mass than neutrons or protons 9.110x10-28 grams.

Atomic Number This is the number of protons in a nucleus of an

atom of a particular element. Mass Number

This is the total number of protons and neutrons in the nucleus of an atom of a particular element.

Chlorine -37 or 37Cl17

Isotopes These are atoms that have a different atomic mass

number than other atoms of the same element. They have a different number of neutrons than

others.