Question

Arrange the following elements in the decreasing order of their first ionisation energy.

A - Boron (B)
B - Carbon (C)
C - Beryllium (Be)
D - Oxygen (O)

Answer 1

The element at the bottom left of the rectangle in the periodic table, Rb, will have the lowest first ionization energy.

Step-by-step explanation:

Solution:

These six elements form a rectangle in the two far-left columns of the periodic table. Because we know that ionization energies increase from left to right in a row and from bottom to top of a column, we can predict that the element at the bottom left of the rectangle will have the lowest first ionization energy: Rb.