Ion Formation & Ionic Bonding

Ion Formation• Atoms are most stable when their valence shell is

full and their electron configuration is isoelectric of a noble gas.

• An ion is an atom that has gained or lost electrons to gain a stable octet.• an atom that loses electrons, has a positive

charge is called a cation.• An atom that gains electrons, has a negative

charge and is called an anion.

Ion Formation Equations

• Na + IE Na+ + e-

o Na has 1 valence electron, so applying Ionization Energy, the electron is removed and , it achieves the same electron configuration as Ne.

• O + 2e- O2- + EAo O has 6 valence electrons, so by gaining 2 electrons, it achieves the

same electron configuration as Ne. Electron affinity energy is released.

Try These…• Give the ion formation equations for:

a) Cl-

b) Mg2+

c) N31

Ionic Bonding• Occurs when atoms exchange electrons to satisfy

their stable octets. The resulting cation(s) and anion(s) are attracted to each other by electrostatic forces and a compound is formed.

• Using Lewis diagrams, we can show the formation of ionic compounds.

• Eg. Na Cl

Learning Check• 1. Use Lewis dot diagrams to illustrate the formation of:

a) lithium iodideb) barium chloridec) potassium oxided) calcium fluoride

2. Predict the formula of each compound:e) magnesium chloridef) sodium sulfideg) aluminum oxideh) barium chloridei) calcium fluoridej) sodium iodidek) potassium chloride

Binary Ionic Nomenclature

Remember:

• A cation is named with its regular nameo Eg. Magnesium is the “magnesium ion”

• An anion is named with the –ide suffixo Eg. Cl- is the “chloride ion”

Writing Formulas:1. Write the chemical symbols2. Add the ion charge3. Determine how many ions of each type are needed

using the crossover method.**Remember: all compound must be zero

Practice• Write the chemical formula for the following ionic

compounds and name the compounds.

1. Magnesium and chlorine2. Sodium and nitrogen3. Calcium and sulphur4. Aluminum and oxygen

Multivalent Ions

Polyatomic Ions