The periodic table we use today is based on the work of Dmitri Mendeleev.
Mendeleev left gaps in his early periodic table. State one reason why he left these gaps.
Mendeleev ordered elements mainly by atomic weight, but he switched the positions of some elements, such as tellurium and iodine. Explain why he did this.
The table below shows the boiling points of four elements in Group 7 (the halogens).
| Element | Boiling point (∘C^\circ\text{C}∘C) |
|---|---|
| Fluorine | −188-188−188 |
| Chlorine | −34-34−34 |
| Bromine | XXX |
| Iodine | 184184184 |
Predict the value of XXX.
When chlorine gas is bubbled through a solution of potassium bromide, a displacement reaction occurs. State the color change observed in the solution.
Which of the following is the correct chemical formula of a fluorine molecule?
Practise AQA GCSE Chemistry The periodic table with exam-style questions for Foundation and Higher tier. 25 questions covering The periodic table, Development of the periodic table, Metals and non-metals, Group 0, Group 1, and Group 7, matched to the AQA GCSE Chemistry (8462) specification and written in Paper 1 and Paper 2 style. Every question includes a full worked solution and mark scheme, so you can see where marks are awarded rather than just whether you got the answer right.