Rank the following atoms in order of decreasing atomic radii. Gallium, Sulfur, Helium, and Bismuth

1. Bismuth = 143pm.

2. Gallium = 136pm.

3. Sulfur = 87pm.

4. Helium = 31pm.

Explanation:

Atomic radii can be defined as a measure of the size (distance) of the atom of a chemical element such as hydrogen, oxygen, carbon, nitrogen etc, typically from the nucleus to the valence electrons. The atomic radius of a chemical element decreases across the periodic table, typically from alkali metals (group one elements such as hydrogen, lithium and sodium) to noble gases (group eight elements such as argon, helium and neon) i.e from left to the right of the periodic table. Also, the atomic radius of a chemical element increases down each group of the periodic table, typically from top to bottom (column).

Generally, atoms with relatively large atomic radii tend to have a low electron affinity and a low ionization energy.

To rank the atoms in order of decreasing atomic radii simply means to list or sort them in a descending order i.e from the atom with highest atomic radii to the atom with the lowest atomic radii;

1. Bismuth: has its atomic radius to be equal to 143pm.

2. Gallium: has its atomic radius to be equal to 136pm.

3. Sulfur: has its atomic radius to be equal to 87pm.

4. Helium: has its atomic radius to be equal to 31pm.

Additionally, the unit of measurement of the atomic radius of chemical elements is picometers (1 pm = 10 - 12 m).