PERIODIC TABLE - an organizational system for elements. Elements are arranged in rows going from right to left called Periods and columns going up and down called Families or Groups .
Elements in the same period (horizontal row) have the same number of energy levels.
The period number is the same as the number of energy levels
Atoms get more massive as you move from left to right across the periodic table
Elements in the same family / group have similar properties because they have the same number of valence electrons.
Metals are on the left hand side of the table
Non-metals are on the right-hand side of the table.
Metalloids are between the metals and non-metals.
Group I or Alkali metals - 1 outer-shell electron; they are very reactive, soft, silver
Group II or Alkaline Earth Metals - 2 outer-shell electrons; very reactive, silver
Transition Metals ----> some are silver but not all, 1-2 valence electrons, conductors
Group VII or Halogens - 7 outer-shell electrons, very reactive, non-metals, poor conductors, never uncombined in nature
Group 8 or Noble Gases - Elements whose atoms have full outer shells so they are very unreactive, colorless, odorless, gases