A covalent bond between two atoms occurs when they join together to reach the stable octet, sharing electrons located at the last level. The electronegativity difference between the atoms must be less than 1.7 so that an ionic-type bond does not occur.
The two atoms share one or more pairs of electrons in a new type of orbital called molecular. Covalent bonds occur between atoms of the same non-metal element, between different non-metal atoms, and between a non-metal atom and the hydrogen atom.
Radio and microwaves have longer wavelengths than visible light.
If you go take a look at the electromagnetic spectrum, you will be able to see that visible light waves have a higher frequency and a shorter wavelength ().
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