Periodic Trends

I. Periods

A. period: a horizontal row in the periodic table

B. elements in the same period aren't similar, but they do show trends

1. atomic number/mass increases to the right

2. atomic radius (atomic size) decreases to the right

3. chemical reactivity decreases to the right

4. ionization energy (energy it takes to remove an electron) increases to the right

5. electronegativity (tendency to gain electrons) increases to the right

II. Broad Classes

A. Periodic table can be broken up into 3 broad classes

1. metals: high electrical and heat conductivity, lustrous (shiny), malleable (bendable/can be shaped)

2. nonmetals: poor electrical and heat conductor, dull (not shiny), brittle (breaks instead of bending)

3. metalloids: mixed properties of both metals and nonmetals

-B, Si, Ge, As, Sb, Te, Po, At

III. Bottom two periods are lanthanides and actinides (look at the first elements to figure out why)

Attachments

Periodic Table IP Worksheet - an independent practice worksheet on trends in the periodic table