After today, you will be able to…

•Explain what ionization energy is•Describe the ionization energy

trend from the Periodic Table•Explain why it requires more

energy to remove each subsequent electron after the first

Unit 4: The Periodic Trends

Trends with Ionization Energy (I.E.)

Ionization Energy (I.E.)• The amount of energy required to

remove an electron from a gaseous atom.

Example: Li Li+1 + 1e-• Depends on:

1.Distance between electron and nucleus

2.Nuclear charge (# of protons)

Group trend: I.E. decreases as you go down a group due to a greater # of energy levelsExample: Ionization energy for elements in the same group:

Lithium vs. Cesium e-e-

Easier to remove e- = e- further away from nucleus = lower I.E.

More difficult to remove e- = e- closer to nucleus = higher

I.E.

Period trend: I.E. increases as you move across a period due to an increased nuclear charge

Electrons are held more tightly because of more protons

therefore more I.E. is required to remove an electron

1st Ionization Energies for Elements in the First 6

Periods

It always requires more energy to remove a 2nd or 3rd electron

because they are more attracted to a positive ion than

to a neutral atom.

1st I.E. - Energy required to remove the 1st electron.

2nd I.E. - Energy required to remove the 2nd electron.

3rd I.E. - Energy required to remove the 3rd electron.

1st I.E. < 2nd I.E. < 3rd I.E.

There is a very large increase of ionization energy whenever an

electron is removed from an atom/ion that is isoelectronic with a noble gas.

1st Ionization

Energy

2nd Ionization Energy

3rd Ionization

Energy

Sodium

495.9 kJ

4,560 kJ

Magnesium

738.1 kJ

1,450 kJ

7,730 kJ

Summary: Ionization Energy

Easy way to remember: THE UPSIDE-DOWN SNOWMAN

Decre

ases Increases

Do now: Complete and Turn in “Exit Ticket”

Then: Begin WS 3 (Homework)