Periodic TrendsYou will know what ionization energy is and how it trends on the periodic table

You will know what electron affinity and electronegativity are and how they trend on the periodic table

You will know how cations and anions compare in size to their parent atoms

What Are Ions?Ion Definition - An atom or group of bonded atoms that have a positive or negative charge

Any process that creates an ion is referred toas ionization.

Na+

Sodium cation

Cl- Chloride anion

NH4+

Ammonium cation

SO32-

Sulfite anion

Ionization EnergyThe energy required to remove one electronfrom a neutral atom = ionization energy

A + energy ------> A+ + e-

For main group elements ….

Ionization energy increases across each period

Ionization energy decreases down each group

What determines IE?

• The greater the nuclear charge, the greater IE (for periods)

• Greater distance from nucleus decreases IE (for groups)

Electron AffinityThe energy produced when an electronis added to neutral atom = electron affinity

A + e- ------> A- + energy

Electron Affinity Trend

Electron Affinity: Electron Affinity:

The energy release when an electron is added to an atom. Most favorable toward NE corner of PT since these atoms have a great affinity for e-.

ElectronegativityMeasure of how much an atom can attract electrons

Higher electronegativity results in higher number

Highest value is 4.0 - FluorineLowest value is 0.7 - Francium

Proposed by Linus Pauling --- Useful in describingproperties of compounds

Electronegativity Chart

Trends in Ionic Size(page 175-176 book)

Cations are always smaller than the atoms they come from.

Example: Na+ is smaller than Na

Anions are always larger than the atoms they come from.

Example: F- is larger than F

Ionic Radii vs Atomic Radii

A Closer Look At Ions

Putting it all Together

Alkali metals Alkaline Earth Metals

Braniac Alkali Metals

Halogens Halogens 2

Group Properties of Some Main Group Elements

Noble Gases