Catalyst 1. List an element from the following groups: alkali, alkaline earth metal, transition metal, halogen, and Noble gas. 2. Why do different groups have different properties? 3. Label as metal, non-metal, or semimetal: sodium, silicon, neon, and cobalt. End

Homework Answers

Lecture 1.6 – Ionization Energy

Today’s Learning Target 1.7 – I can define ionization energy and explain how it relates to the charge of the nucleus and the electron. Furthermore, I can explain how this trend changes as you move throughout the Periodic Table.

Nuclear Attraction The negatively charged electrons are attracted towards the positively charged nucleus. The negatively charged electrons are attracted towards the positively charged nucleus. The more the electron “feels” the nucleus. The tighter it is held The more the electron “feels” the nucleus. The tighter it is held

Ionization Energy Ionization energy is the energy that is required to remove an electron. Ionization energy is the energy that is required to remove an electron.

IE Trends As you move down a group the IE decreases. As you move down a group the IE decreases. As you move across a period on the Periodic Table, the IE increases. As you move across a period on the Periodic Table, the IE increases.

Why IE Decreases Down a Group As you go down a group more orbits are added. As you go down a group more orbits are added. Electron Shielding – Valence electrons become shielded from the positively charged nucleus as you add more orbits. Electron Shielding – Valence electrons become shielded from the positively charged nucleus as you add more orbits. IE decreases because it requires less energy to remove an electron due to shielding. IE decreases because it requires less energy to remove an electron due to shielding.

Why IE Increases Across a Period As you move across a period you add more protons and electrons within the same orbit. As you move across a period you add more protons and electrons within the same orbit. The larger amount of protons in the nucleus and electrons in the orbit show an increased attraction. The larger amount of protons in the nucleus and electrons in the orbit show an increased attraction. This leads to a higher IE. This leads to a higher IE.

Class Example Order the elements from smallest to largest IE: potassium, cesium, lithium.

Table Talk Order the elements from largest to smallest IE: Fluorine, Carbon, Oxygen.

Stop and Jot Order the elements from smallest to largest IE: phosphorus, arsenic, nitrogen.

SUMMARIZE

White Board Races

1.Order the following elements from smallest electronegativity to largest electronegativity: Arsenic, Gallium, Germanium. 2.Which element has a larger electronegativity: fluorine or selenium? 3.Which element has a smaller electronegativity: Cesium or Astatine? 4.Why does germanium have a higher ionization energy than lead? 5.Why does silicon have a lower ionization energy than phosphorus?

Closing Time Homework 1.5 – Ionization Energy UNIT 1 TEST NEXT WEDNESDAY!