Question 19M.3.sl.TZ1.b(ii)
| Date | May 2019 | Marks available | [Maximum mark: 1] | Reference code | 19M.3.sl.TZ1.b(ii) |
| Level | sl | Paper | 3 | Time zone | TZ1 |
| Command term | Suggest | Question number | b(ii) | Adapted from | N/A |
Physical properties of elements vary according to atomic number. Sections 6 to 9 of the data booklet list some of these properties.
Suggest, with a reason, whether the lanthanoids or actinoids of the f-block would have the higher density.
[1]
actinoids AND density increases down all groups «due to large increase in atomic mass for small increase in atomic volume»
OR
actinoids AND «much» greater atomic mass with similar type of bonding
OR
actinoids AND density «of actinoids» atomic number 90 to 95 is greater than corresponding lanthanoids [✔]
Note: Accept “actinoids AND on graph actinoids have «much» greater density than lanthanoids”.
Poorly answered. Some students seemed unaware of the terms “lanthanoids” and “actinoids”. Many others just stated the actinoids because they had greater atomic masses, without adding that the bonding, and hence the volume occupied by each atom, would be similar to the lanthanoids. Others responded in terms of the given data, but this required rather more justification than just stating “as can be seen from the graph”.
