Question

Arrange the following ions in order of increasing ionic radius: selenide ion, rubidium ion, bromide ion, strontium ion.

Answer 1

Br, Se, Sr, Rb

Step-by-step explanation:

Atomic radius increases as you move to the left and down the periodic table. The increase in radius as you move left is due to decreasing effective nuclear charge (the pull an electron feels from the nucleus) since the number of protons decrease. The increase in radius as you move down is due to a higher number of principle energy levels (orbital in which the electron is located relative to the atom's nucleus), causing the electrons to be farther from the nucleus.