Mendeleev left a gap in his table below silicon. He predicted the properties of an element to fill the gap and called it eka-silicon. In 1886, germanium was discovered.
The table compares Mendeleev's predictions with the properties of germanium.
| Property | Predicted for eka-silicon (1871) | Measured for germanium (1886) |
|---|---|---|
| relative atomic mass | 72 | 72.6 |
| density in g cm−3\mathrm{g\,cm^{-3}}gcm−3 | 5.5 | 5.35 |
| formula of oxide | EsO2\mathrm{EsO_{2}}EsO2 | GeO2\mathrm{GeO_{2}}GeO2 |
| formula of chloride | EsCl4\mathrm{EsCl_{4}}EsCl4 | GeCl4\mathrm{GeCl_{4}}GeCl4 |
Explain why Mendeleev left a gap below silicon rather than putting the next known element there.
Silicon forms an oxide with the formula SiO2\mathrm{SiO_{2}}SiO2. Suggest how Mendeleev was able to predict the formula of the oxide of eka-silicon.
Compare Mendeleev's predictions with the measured properties of germanium. Use data from the table.
Explain why the discovery of germanium made other scientists accept Mendeleev's periodic table.
50 exam-style questions on Edexcel GCSE Chemistry 2.2 The periodic table, covering 2.2.1 Mendeleev's periodic table, 2.2.2 Periods, groups, metals and non-metals, and 2.2.3 Electronic configuration and position in the periodic table. Each one has a worked solution and a mark scheme showing where the marks go.