Ionic Bonding

New Unit: Chemical Bonding

Essential Questions:

What are the processes by which different atoms come together to form new compounds and what forces hold solutions of these compounds/molecules together?

Ions

An atom with a charge Positive: cation Negative: anion

How do these atoms become charged?

Valence Electrons

Electrons in the highest occupied energy level

The number of valence electrons greatly determines chemical properties of an element and how it will react

How can we find the number of valence electrons in an element?

By using electron configurations

Electron configuration for chlorine:

1s22s22p63s23p5

What is the highest energy level reached? 3

How many electrons are there? 7

Because of trends, we can also use group numbers!

Looking at the electron configuration for elements in the same group, they will all have the same number of valence electrons (just the A groups though! Not the B groups.)

Guided Practice on Valence Electrons

How many valence electrons are there in the following elements?

ChlorineCalciumAluminum CarbonNeon

Electron Dot Structures

Also known as Lewis Structures Diagrams that represent the number

of valence electrons in the atom

1. Find number of valence electrons2. Write element symbol3. Fill valence electrons around symbol,

one on each side first then double up

Guided Practice on Lewis Structures

Find the Lewis Dot Structures for the following elements:

ChlorineCalciumAluminum CarbonNeon

Octet Rule

Noble gases are the most stable elements on the Periodic Table due to the fact that they have 8 valence electrons (a complete outer shell)

Atoms will either lose or gain electrons through bonding in order to attain those complete 8 configurations Metal elements tend to lose electrons

while nonmetals tend to gain

Forming ions

How do cations form? Losing valence electrons▪ Who tends to form cations?

How do anions form? Gaining valence electrons ▪ Who tends to form anions?

Forming cations

Metals Lose valence electrons

Example: Calcium Normal calcium calcium ion

20 protons 20 protons20 electrons 18 electronsno charge +2 charge

Forming anions

Nonmetals Gain electrons to get to an octet

Example: Chlorinenormal chlorine chlorine ion

17 protons 17 protons

17 electrons 18 electronsno charge -1 charge

Independent Practice

Formation of Ionic Compounds

Composed of a cation and an anion Held together by ionic bonds Represented by a chemical formula A formula unit is the lowest whole-

number ratio of ions in an ionic compound

Formation of Ionic Compounds

When writing the formulas, use the criss-cross method

Mg+2 Cl-1

MgCl2

Showing Ionic Bonding with Lewis Structures

Showing Ionic Bonding with electron configurations

Guided Practice on Ionic Compound Formulas

For the following pairs of elements, write the formula for the ionic compound formed

Aluminum and ChlorineSodium and SulfurNitrogen and fluorine

Independent Practice