Atomic radius:
Atomic radius is the distance from the nucleus to the outermost electron shell of an atom. It is an important property of an atom as it helps determine the size of the atom and its chemical behavior. Atomic radius can be measured using different methods, and various types of atomic radii are used to explain different aspects of an atom's size and behavior.

Types of atomic radii:
There are several types of atomic radii used to explain the size of an atom. These include:

1. Coordinate radius:
Coordinate radius is not used to explain atomic radius. It is a term used in coordination chemistry to describe the distance between the central metal ion and the surrounding ligands in a coordination complex. It is not directly related to the size of the atom itself.

2. Covalent radius:
Covalent radius is the distance between the nuclei of two atoms bonded together by a covalent bond. It is used to explain the size of atoms in covalent compounds. Covalent radius is typically smaller than the atomic radius because covalent bonds involve the sharing of electrons between atoms, which causes the atoms to be pulled closer together.

3. Van der Waals radius:
Van der Waals radius is the distance between the nuclei of two non-bonded atoms in a molecule or crystal lattice. It is used to explain the size of atoms in non-covalent interactions, such as van der Waals forces. Van der Waals radius is larger than the covalent radius and represents the size of the atom when it is not involved in any chemical bonding.

4. Metallic radius:
Metallic radius is the distance between the nuclei of two adjacent metal atoms in a metallic lattice. It is used to explain the size of metal atoms in metallic structures. Metallic radius is typically larger than the atomic radius due to the presence of delocalized electrons in metal structures, which cause the atoms to be pushed apart.

Conclusion:
In conclusion, coordinate radius is not used to explain atomic radius. Instead, covalent radius, van der Waals radius, and metallic radius are used to describe different aspects of an atom's size and behavior.