Answer
The unit used to express the size of an atom is called:
Atomic Radii.
The atomic radius is a measure of the size of an atom. The atomic radius is defined as one-half the distance between the nuclei of two identical atoms that are bonded together.
r is atomic radius of an atom and d is distance between the nuclei of two identical atoms
Atomic radius is dependent on the type of bond present. Types of bonds can be grouped as five descriptive types.
- Ionic bonds
- Covalent bonds
- Metallic bonds
- van der Waals bonds
- Hydrogen bonds
Units used to measure atomic radius:
- Angstroms (Å): This the most common unit used. Equivalent to 1.0 x 10-10 meters.
- Nanometer (nm): Equivalent to 1.0 x 10-9 meters.
- Picometer (pm): Equivalent to 1.0 x 10-12 meters.