SL Chem - Unit #1: Ionic Bonding

Ionic Bonds

A bond made by the transfer of electrons to make each atom have a stable octet

Ionic Compounds

A pure substance (made of a metal and non-metal) that are made from the electrostatic attraction of opposite ions

• Identified by their electronegativity difference is greater than 1.7

Properties of Ionic Compounds

• High melting/boiling point

• Form Crystals

• Low Volatility

• Soluble in polar covalent solutions ONLY

• Conduct electricity when they have delocalized ions

Volatility

Referring to how often/the rate a substance evaporates

In what state can ionic compounds conduct electricity?

Ionic compounds can only conduct electricity in molten/aqueaous state

• When they have delocalized ions that allows for movement to help conduct electricity

Positive Ion (Cations)

Loses electrons to form a stable valence shell

• Lower electronegativity and electron affinity

• Lower ionization energy is required to remove an electron since they’re already trying to lose their electrons

  • Some transition metals have multiple ions (different charges)

Negative Ion (Anion)

Gains electrons to form a stable valence shell

• They have higher electronegativity and electron affinity

• They have a higher ionization energy since it require more energy to remove an electron from its valence shell

Steps to Ionic Bonding (3)

1. Loss of electrons in metals because of their low ionization energy

   • Ca → Ca²⁺ + 2e^-

2. Gain of electrons in non-metals because of their high electron affinity

   •  O + 2e^- → O^2- 

3. The attraction between the positive and negative ions

   • Ca²⁺ + O^2- → CaO

Isoelectronic

An ion and other atoms/ions that have the same number of electrons are called isoelectronic

• When atoms form ions their stable arrangement can have the same number of electrons(arrangement) as other ions/atoms

Drawing an Ionic Bond with Lewis Dot Diagram

1. Shows the electron transfer from the cation to the anion with arrows

2. Then redraw the final ionic diagram using the square brackets around them to show stability with its charge as a superscript and number of each element as a subscript