1. TRENDS ON TABLE 1. Atomic Radius (size)
Going across a period, size gets SMALLER
WHY?
More protons pull outer electrons in more strongly
Going down a column, size gets LARGER
More electron shells (principal energy levels) are added, each larger than the shell below

2. Use the BorAst Staircase.
How do you know if it is a metal, a nonmetal or a metaloid?
Use the BorAst Staircase.
Metal = element with a tendency to lose electrons in reactions
Nonmetal = element with a tendency to gain electrons in reactions
Metalloid = element that can’t make up its mind

3. 2. Metallic activity or reactivity
Going across a period, reactivity of metals gets LESS
WHY?
More protons pull outer electrons in more strongly, so they are harder to lose

4. Going down a column, reactivity of metals gets GREATER
WHY?
More electron shells (principal energy levels) are added, so outer electrons are farther from the nucleus and thus easier to lose
So metals are to the left and down

5. 3. Nonmetallic activity or reactivity
Going across a period, reactivity of nonmetals gets GREATER
WHY?
More protons pull outer electrons in more strongly, so they are easier to gain
Example: Brainiac: Alkali Metals

6. Going down a column, reactivity of nonmetals gets LESS
WHY?
More electron shells (principal energy levels) are added, so outer electrons are farther from the nucleus and thus harder to gain
So nonmetals are to the right and up

7. Other Trends -Atomic Mass -Electronegativity -Atomic Number
-Oxidation States