Year 9 Science · Unit 2 · Lesson 07
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Learning Goals
Order the steps
Number the events from 1 to 6 to show the correct order for forming a sodium ion from a sodium atom. Event 1 = what happens first.
| Order | Event |
|---|---|
| Sodium loses the outer-shell electron. | |
| The resulting ion, Na⁺, has the electron configuration 2,8, the same as the noble gas neon. | |
| Identify that the outer shell has only 1 electron. | |
| Write sodium's electron configuration: 2,8,1. | |
| Sodium must lose 1 electron to reach a full outer shell (achieving noble gas configuration). | |
| Sodium becomes Na⁺, it is now positively charged because it has more protons than electrons. |
Ion formation comparison table
Complete the table for each element. The element name and electron configuration are given. Fill in the remaining four columns.
| Element | Electron config. | Valency | Electrons gained (−) or lost (+) | Ion symbol | Ion charge |
|---|---|---|---|---|---|
| Sodium (Na) | 2,8,1 | ||||
| Magnesium (Mg) | 2,8,2 | ||||
| Aluminium (Al) | 2,8,3 | ||||
| Oxygen (O) | 2,6 | ||||
| Sulfur (S) | 2,8,6 | ||||
| Chlorine (Cl) | 2,8,7 |
(a) What pattern do you notice between an element's group in the periodic table and the charge of the ion it forms?
(b) Magnesium and sulfur react together. Using the ion symbols from your table, explain how ions are transferred in this reaction and write the formula of the ionic compound formed.
(c) Why does oxygen gain 2 electrons rather than lose 6 electrons to achieve a full outer shell?
1. A mystery element has electron configuration 2,8,2. Identify which ion it will form, write its symbol with charge, and state which group of the periodic table it belongs to.
2. Calcium (Ca) is in Group 2. Nitrogen (N) has electron configuration 2,5. Predict the ions formed by each element and use their valencies to write the formula of calcium nitride.
Wrap Up
In one sentence, what was the main idea of this lesson?