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Comparing sodium and potassium electrons
Sodium and potassium are in Group 1 of the periodic table.
Give one similarity and one difference between the electronic structures of sodium and potassium.
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Marking points
- 1 Similarity field states that each atom has one outer-shell electron.
- 2 Difference field compares their shell counts: sodium has three and potassium four.
Full-mark answer
Similarity: both have one electron in their outer shell. Difference: sodium has three occupied electron shells, whereas potassium has four.
Why this answer loses marks
They both have the same number of shells.
The group similarity is the outer electron; their different periods mean different shell totals.