Ionic Compounds

Mahi Tuatahi / Do Now

1. Complete another element quiz!
2. You can move onto the next question set if you score 30/30 two days in a row!
3. Record your score on your scoresheet

Ions

Ions are atoms that have gained or lost electrons in order to have a full valence shell.

Valence: outermost

Example

This is an oxygen atom. Copy the diagram into your book and give the electron shell configuration e.g. [2,3]

Making an ion is like rounding:

• Atoms with a less than half-full valence shell will perfer to lose electrons
• Atoms with a more than half-full valence shell will prefer to gain electrons

Think again about the oxygen atom and answer these questions:

1. Will it prefer to gain or lose electrons?
2. How many electrons will it need to gain/lose to have a full outer shell?

Copy this table into your own book and work in pairs to complete it.

Writing Ions

• Writing ions comes in two parts: the element, and the charge.
• The charge goes in a superscript ^{like this}.
• The number goes before the charge.

\[ \begin{aligned} O^{2-} \end{aligned} \]

Making Ionic Compounds

• To make ionic compounds we need the numbers in the superscript to balance to zero.
• To use more than one of an ion you use a subscript _{like this}

\[ \begin{aligned} Na^{+} + Cl^{-} &\rightarrow NaCl \newline Cu^{2+} + 2OH^{-} &\rightarrow Cu(OH)_{2} \end{aligned} \]

Electron Transfer

Ionic compounds form because:

• some atoms want to give away electrons to get a full valence shell (become positive)
• some atoms want to receive electrons to get a full valence shell (become negative)

By giving/receiving electrons they form an ion becoming positive or negatively charged. Once they have a charge they are elecrostatically attracted together and make a neutral compound.

Mahi Tuatahi

Quiz! If you have scored 30 twice in a row with the elements you can try and ions quiz today!

Tākaro / Game!

• Form into your table groups/pairs with a whiteboard. We are going to make some ionic compounds. Most points wins!

Your answer is simply to give the compound like this: \(NaOH\) has 1x \(Na^{+}\), 1x \(OH^{-}\).

Whakatika

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