Question

Based on their positions in the periodic table, list the following atoms in order of increasing radius: Mg, Ca, Rb, Cs.

a) Cs, Rb, Ca, Mg
b) Mg, Ca, Rb, Cs
c) Ca, Mg, Rb, Cs
d) Mg, Ca, Cs, Rb

Answer 1

The order of increasing atomic radii for Mg, Ca, Rb, Cs is Mg, Ca, Rb, Cs. This sequence is based on the understanding that atomic radii increase down a group and decrease across a period.

Step-by-step explanation:

To list the following atoms in order of increasing radius based on their positions in the periodic table: Mg, Ca, Rb, Cs, we take into account two main trends:

• Atomic radii generally increase as we move down a group (column) because additional energy levels (shells) are added, which are further from the nucleus.
• Atomic radii generally decrease as we move across a period (row) from left to right because the number of protons increases, pulling the electrons closer to the nucleus.

Magnesium (Mg) and Calcium (Ca) are in the same group (alkaline earth metals) with Mg above Ca, so Ca has a larger atomic radius than Mg. Rubidium (Rb) and Cesium (Cs) are in the same group (alkali metals) with Rb above Cs, so Cs has a larger atomic radius than Rb. Between groups, Rb and Cs, being alkali metals, have larger atomic radii than the alkaline earth metals Mg and Ca.

The correct order of increasing atomic radii is: Mg, Ca, Rb, Cs.