Metals and non-metals in the periodic table
3 marks · NormalThe table below shows four elements, their position in the periodic table, and the formula of the oxide formed when each reacts with oxygen:
| Element | Group | Period | Formula of oxide |
|---|---|---|---|
| A | 2 | 3 | MgO |
| B | 7 | 2 | Cl2O7 |
| C | 1 | 2 | Na2O |
| D | 6 | 3 | SO3 |
Classify each element in the table as a metal or a non-metal based on its position in the periodic table.
Use the character of their oxides to explain your classifications for element C and element D.
Work this out on paper, then compare with the answer and worked solution below. With a free account you can submit written answers for marking.
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(a) — · must show A: Metal, B: Non-metal, C: Metal, D: Non-metal
(b) — · must show C: basic oxide, D: acidic oxide; reasoning ties oxide type to metal/non-metal character
Common mistakes: Mixing up acidic/basic oxides; Incorrect classification of Group 1 or 6 elements
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Marking points
B1 (a) · 1 mark · Correctly classify both metals (A and C)
B2 (a) · 1 mark · Correctly classify both non-metals (B and D)
M1 (b) · 1 mark · Correctly explains that C forms a basic oxide (as a metal) and D forms an acidic oxide (as a non-metal), linking the character of the oxide to the classification
Worked solution
a) Classification by periodic table position:
| Element | Classification |
|---|---|
| A | Metal |
| B | Non-metal |
| C | Metal |
| D | Non-metal |
A (Group 2, Period 3) is magnesium (Mg), a metal. B (Group 7, Period 2) is a Group 7 non-metal (chlorine). C (Group 1, Period 2) is sodium (Na), also a metal. D (Group 6, Period 3) is sulfur (S), a non-metal.
b) Explanation using oxide character:
Element C forms Na2O, which is a basic oxide (a property of metals). Element D forms SO3, which is an acidic oxide (a property of non-metals). This supports their classification: metals form basic oxides, non-metals form acidic oxides.