An atom consists of two basic parts: the nucleus and the electrons. The nucleus is the central core of an atom and is made up of protons and neutrons. Electrons are very light, negatively charged particles that surround the positively charged nucleus. Early models of the atom depicted the electrons circling the nucleus in fixed orbits, much like planets revolving around the sun.
Current theory suggests that electrons are housed in orbitals. This is a valence orbital or valence orbit
Explanation:
The outermost orbital shell of an atom is called its valence shell, and the electrons in the valence shell are valence electrons. Valence electrons are the highest energy electrons in an atom and are therefore the most reactive. this is where your valence orbit gets its name because it is the outermost shell.
