Question

The range of atomic numbers of lanthanide series of elements is:
A) 90-103
B) 89-102
C) 58-71
D) 71-103

Answer 1

Hint: The answer to this question lies in the basic concept of chemistry that deals with the periodic table that shows the groups, periods and the range and properties of the elements which has atomic and mass numbers depicted with it.

Complete answer:
In our lower classes, we have studied about the periodic table that was proposed by various scientists and now the existing periodic table that is the modern periodic table gives us much information.
Now, let us see what the periodic table and the contents present in it.
- Periodic table is that one which contains lists of elements existing and that are arranged according to their atomic numbers, electronic configuration and recurring chemical properties.
- From this periodic table, we can get information about elements like ionisation enthalpy, electron affinity trends and so on.
- The elements in a periodic table are placed according to the increasing atomic number that is the presence of a number of protons in its nucleus.
- Based on the properties they are grouped into s, p, d and f block elements.
- Since lanthanides and actinides are together placed at the end of periodic table (in f- block), their atomic number starts from 27 that is lanthanum. Since, the series starts from the next number that is 58, the lanthanide series ranges from 58-71.

Thus, the correct answer is option is C) 58-71.

Note: Note that lanthanides and actinides belong to the f – block elements and this type of questions can be answered when you are thorough with the basic information required from the periodic table.