Periodic Trends Periodic Trends What is a trend

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