1. Chapter five – periodic Law
Chemistry
Chapter five – periodic Law
South Lake High School
Science Department
Ms. SANDERS

2. Periodic Trends Atomic Radius:
One-half the distance between the nuclei of identical atoms that are bonded together
Decreases across a period (more protons or nuclear force which pulls in the electrons)
Increases down a group (adds electrons in energy levels further away from nucleus)
Francium – largest atomic radius
Helium – smallest atomic radius

3. Periodic Trends Ionization Energy:
Energy required to remove an electron
Increases across a period (stronger nuclear force holding the electrons)
Decreases down a group (electrons are further away from the nucleus)
Noble Gases – highest ionization energy

4. Periodic Trends Electron Affinity:
Energy change associated with the addition of an electron
Increases across a period (not Noble Gases = 0)
Decreases down a group
Halogens (group 17) – highest electron affinity

5. Periodic Trends Electronegativity:
Measure of the ability of an atom to attract electrons from another atom
Increases across a period
Decreases down a group
Fluorine – highest electronegativity