Lecture 2.5 – Electronegativity

What is electronegativity?

I. Electronegativity

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

What are the trends for electronegativity?

I. Electronegativity Trends

  • As you go down a group, the electronegativity decreases.
  • As you go across a period, the electronegativity increases.

Se, Ni, Ca

Po, S, O

Cs, Ga, F

Class Example

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

Li, Be, O

Table Talk

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

Br, Cl, F

Stop and Jot

  • Order the elements from smallest to largest electronegativity: silicon, aluminum, sulfur

Al Si, S

Why do these trends exist?

I. Why Electronegativity Decreases Down a Group

  • As you go down a group more orbits are added.
  • Electroneg. decreases because there is a decreased ability of the nucleus to attract electrons because of larger distance.

II. Why Electronegativity Increases Across a Period

  • 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 orbit show an increased attraction, which leads to increased electroneg.
2.5.Electronegativity.pptx - Google Slides