Periodic Trends

Periodic Trends What is a trend? A trend is the general direction in which something tends to move.

Periodic Trends The elements on the Periodic Table of Elements show many trends in their physical and chemical properties. Across the rows (periods or series) Down the columns (groups or families)

Atomic Radius ½ the distance between the nuclei of 2 like atoms in a diatomic molecule The atoms of the 8 main groups are shown here.

Atomic Radius - Groups Atomic radius increases as you move down a group Why? More electrons in more Principal Energy Levels Atomic size increases

Atomic Radius - Periods Atomic radius decreases as you move across a period Why? (-) electrons increase, but so do (+) protons !!! Increased (+) nuclear charge pulls the (-) electrons closer to the nucleus Atomic size decreases

Ionization Energy Is the Energy needed to remove an electron from an atom Increases from left to right on the periodic table Also increases going up the bottom to the top of the periodic table

Ionization Energy

Electronegativity - Periods Electronegativity is the strength of which an element pulls electrons. Electronegativity increases going left to right across the periodic table. Electronegativity decreases going down a group Li Be B C N O F 1.0 1.5 2.0 2.5 3.0 3.5 4.0

Electronegativity - Groups Electronegativity decreases going down a group H 2.1 Li 1.0 Na 0.9 K 0.8 Rb 0.8 Cs 0.7 Fr 0.7

Electronegativity

Electronegativity