CHEM 1211 CH.4

pure substances that cant be seperated into simpler substances by ordinary laboratory processes

Building blocks of matter

represents the name of an element

contain elements with similar properties in vertical columns

horizontal row of elements

Group 1A

Group 7A

Atoms are tiny particles of matter

Atoms are of two or more different elements combine to form compunds

Discovered that cathode rays were streams of small negatively charged particles called electrons

There must be small, dense positively charged nucleus in the atom that deflects positive particles that come close

1.007

1.008

0.00055amu

Identifies the Element

Specific for each element

Equal to the number of protons in an atom

Equal to number of protons + number of neutrons

are atoms of the same element that have different mass numbers

have the same number of protons but different number of neutrons

gives the mass number in the upper left corner and the atomic number in the lower left corner

listed below the symbol of the element

gives the mass of an "average" atom

Not the same as mass number

Aluminum

Argon

Arsenic

Barium

Boron

Bromine

Cadmium

Calcium

Carbon

Chlorine

Chromium

Cobalt

Copper

Fluorine

Gold

Helium

Hydrogen

Iodine

Iron

Lead

Lithium

Magnesium

Manganese

Mercury

Neon

Nickel

Nitrogen

Oxygen

Phosphorus

Platinum

Potassium

Radium

Silicon

Silver

Sodium

Strontium

Sulfur

Tin

titanium

Uranium

Zinc