Lemonade-Ed - Lesson: Ionic Formulae

Lemonade-Ed

Lesson Plan: Ionic Formulae

Navigate the knowledge tree: 🌿 Chemistry ➡ Chemical Changes ➡ Ions

Hei Mahi (Do Now)

Do Now on your Whiteboard

Q1: What is an atom?

Q2: Name the 3 particles inside an atom.

Q3: What do you call an atom that has gained or lost electrons?

Hei Mahi (Do Now) ANSWERS

Do Now on your Whiteboard

Q1: What is an atom? The smallest particle of matter. The building blocks of chemistry.

Q2: Name the 3 particles inside an atom. Protons (+), electrons (-) and neutrons (neutral).

Q3: What do you call an atom that gained or lost electrons? Ion

Knowledge: Formation of Ions

Atoms are neutral, they have the same number of protons (+) and electrons(-) particles.
Most atoms are unstable, they do not have a full outer shell of electrons.
To become stable, atoms will lose of gain electrons to have a full outer shell.

Go to 🌿 Ions

Knowledge: Charges on Ions

The atoms of the elements in group 1, 2 and 3 will lose electrons and form positive ions.
The atoms of elements in group 5, 6 and 7 will gain electrons to form negative ions.

Go to 🌿 Ions

Activity: sciPad

Complete sciPad pages 10-11 'How Atoms Become Ions'.

Knowledge: Naming Positive Ions (Cation)

As a general rule, just add the word "ion" to the name of the atom.

Go to 🌿 Ions

Knowledge: Naming Negative Ions (Anion)

For monoatomic atoms (single atoms), take the root of the element name, then add the suffix "-ide".

For polyatomic ions containing oxygen, add the suffix "-ate". However, there are many exceptions that you will just have to memorise.

Go to 🌿 Ions

Activity: sciPad

Complete sciPad pages 12 'Naming Ions'.

Knowledge: Ionic Formulae

A chemical formula is a shorthand way of writing the name of a chemical compound. It uses the symbols of the chemicals taking part in the reaction. There are two rules for working out the formulae for a simple compound:

Rule 1: If the ion charges are equal, then one of each will combine. See the example of magnesium oxide below.

Rule 2: If ion charges are unequal, then drop the number in front of the charge to the line (from superscript to subscript) and swap sides. See the example below for sodium oxide - the charges for sodium and oxide were dropped and swapped.

In some cases, you will need to:

Simplify subscripts if they have a common factor (see the example below for aluminium phosphide).
Use brackets for more than one polyatomic ion (see the example below for calcium phosphate).