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

Quiz You have 20 minutes to complete the quiz This should be done without notes and should be completed silently.

Homework Answers

Lecture 1.7/1.8 – Ionization Energy and Electronegativity

Today’s Learning Target 1.7/1.8 – I can define ionization energy/electronegativity, explain how they relate to the charge of the nucleus and the electron, and discuss how they change moving around the PT.

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

Ionization Energy Ionization energy is the energy that is required to remove a valence electron. Ionization energy is the energy that is required to remove a valence electron.

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

IE Trend: Group As you go down a group more orbitals are added. As you go down a group more orbitals are added. Electron Shielding – Valence electrons become shielded from the positively charged nucleus as you add more orbitals. Electron Shielding – Valence electrons become shielded from the positively charged nucleus as you add more orbitals. 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.

IE Trend: 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. More protons and electrons = more +/- interaction More protons and electrons = more +/- interaction This leads to a higher IE because stronger +/- interactions increase the energy required to remove an electron. This leads to a higher IE because stronger +/- interactions increase the energy required to remove an electron.

Class Example Order the elements from smallest to largest Ionization Energy: Potassium (K), Cesium (Cs), Lithium (Li).

Table Talk Order the elements from largest to smallest IE: Fluorine (F), Carbon (C), Oxygen (O).

Stop and Jot Order the elements from smallest to largest IE: Phosphorous (P), Arsenic (As), Nitrogen (N).

SUMMARIZE

White Board Races

Question 1 Order the following elements from smallest ionization energy to largest ionization energy: Arsenic, Gallium, Germanium.

Question 2 Which element has a larger ionization energy: fluorine or selenium?

Question 3 Which element has a smaller ionization energy: Cesium or Astatine?

Question 4 Why does germanium have a higher ionization energy than lead?

Question 5 Why does silicon have a lower ionization energy than phosphorus?

2 MINUTE BREAK

Electronegativity Electronegativity is the measure of the ability of an atom to attract/STEAL electrons.

EN Trends As you go down a group, the EN of an element decreases. As you go across a period, the EN of an element increases.

EN Trend: Group As you go down a group more orbits are added. Electron Shielding EN decreases because there is a decreased ability of the nucleus to attract electrons because of larger distance.

EN Trend: Period As you move across a period you add more protons and electrons within the same orbit. Larger amount of protons in the nucleus and electrons in orbit show an increased attraction. This leads to increased electronegativity as you move within a period.

Class Example Order the elements from smallest to largest electronegativity: oxygen, beryllium, lithium,

Table Talk Order the elements from largest to smallest electronegativity: chlorine, bromine, fluorine

Stop and Jot Order the elements from smallest to largest electronegativity: silicon, aluminum, sulfur

SUMMARIZE

Relay Race Problems 1.Which has a larger electronegativity: chlorine or silicon? 2.Which has a smaller electronegativity magnesium or calcium? 3.Put the following elements in order from smallest electronegativity to largest: B, F, N, O. 4.Put the following elements in order from smallest electronegativity to largest: N, As, Bi, P. 5.Why does bromine do a worse job of attracting electrons than fluorine?

Relay Race Problems (Part Deux!) 1. Which element has the larger ionization energy: fluorine or carbon? 2. Which element has the smaller ionization energy: beryllium or magnesium? 3. Put the following elements in order from smallest ionization energy to largest: Sr, Ba, Be, Mg. 4. Put the following elements in order from largest ionization energy to smallest: Al, Cl, Si, P. 5. Why does cesium have a smaller ionization energy than rubidium?

Exit Ticket

Rate Yourself Based on the exit ticket and your current level of understanding, rate yourself 1 – 4 on LT 1.7 and 1.8

Closing Time Homework 1.7/1.8 – Ionization Energy and Electronegativity will be assigned Mon./Tues. UNIT 1 TEST NEXT WEDNESDAY!