Mendeleev left a gap below silicon for an undiscovered element, which he called eka-silicon (E). He predicted its properties from the elements directly above and below it in the same group.
| Element | Relative atomic mass | Density (g cm−3\mathrm{g\,cm^{-3}}gcm−3) | Formula of oxide |
|---|---|---|---|
| silicon | 28.1 | 2.3 | SiO2\mathrm{SiO_{2}}SiO2 |
| eka-silicon | ? | ? | ? |
| tin | 118.7 | 7.3 | SnO2\mathrm{SnO_{2}}SnO2 |
Which row gives the best predictions for eka-silicon?
relative atomic mass 73.4; density 4.8; oxide EO4\mathrm{EO_{4}}EO4
relative atomic mass 73.4; density 4.8; oxide EO2\mathrm{EO_{2}}EO2
relative atomic mass 90.6; density 5.0; oxide EO2\mathrm{EO_{2}}EO2
relative atomic mass 146.8; density 9.6; oxide EO2\mathrm{EO_{2}}EO2
80 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.