Atomic radii

[Sei Lam 3F]

Hello! Could someone explain the difference between atomic, covalent, and ionic radii? How do they relate to periodic trends like ionization energy and electronegativity? Thanks!

[Araceli 3H]

Hi! Atomic radius refers to the size of an atom, usually defined as the distance from the nucleus to the outermost electron shell. Atomic radius increases down a group (from top to bottom) in the periodic table and decreases across a period (from left to right). Covalent radius is related to the size of atoms when they are bonded in a molecule by a covalent bond. Covalent radii generally increase down a group and decrease across a period. Ionic radius refers to the size of ions, which are atoms that have gained or lost electrons to become charged. Ionic radii follow similar trends to atomic and covalent radii. Ionization energy is the energy required to remove an electron from an atom or ion. Smaller atoms (with smaller atomic or ionic radii) have higher ionization energies because electrons are closer to the nucleus and experience a stronger attractive force. Electronegativity is the ability of an atom to attract electrons in a chemical bond. Smaller atoms (with smaller atomic or ionic radii) often have higher electronegativities because their electrons are closer to the nucleus and are more strongly attracted.

[DevanCornelio_1I]

Atomic radius is the radius of an atom itself. Covalent and ionic radii are the radius between the two centers of the atoms in a covalent and ionic bond.