PERIODIC TABLE

BASIC INFORMATION

• The periodic table we use today is based on the one devised and published by Dimitri Mendeleev in 1869.
• Mendeleev found he could arrange the 65 elements then known in a grid or table so that each element had.
• 1. A higher atomic weight than the one on its left.
• 2. Similar chemical properties to other elements in the same column.

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• Monseley had found that elements are different from one to another because their atoms
• Have differents number of protons. He discovered that elements positions in the periodic table
• are better predicted by their atomic numbers than their atomic weight.
• Horizontal rows are call Periods.
• Vertical rows are call Groups.

ELECTRONS

• Electrons in atoms can be pictured as occupying layers or shells
• surrounding the atomic nucleus.

VALANCE ELEMENTS

• It is the valance electrons which cause chemical activity.
• Group 1 one valance electrons.
• Group 2 two valance electrons
• Group 13 three valance electrons
• Group 14 four valance electrons

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