The number of electrons in the outermost shell of a particular atom determines its reactivity, or tendency to form chemical bonds with other atoms. This outermost shell is known as the valence shell, and the electrons found in it are called valence electrons.

Do outer shells have one or two electrons?

The outermost orbital shell of an atom is called its valence shell. These electrons take part in bonding with other atoms. ... (a) Lithium (Li), Sodium (Na), Potassium (K) are the elements having single electron in their outermost electron. (b) Magnesium (Mg), Calcium (Ca) has two electrons in the outermost shell.

Why is the outer shell of electrons?

Electrons in outer shells have higher average energy and travel farther from the nucleus than those in inner shells. This makes them more important in determining how the atom reacts chemically and behaves as a conductor, because the pull of the atom's nucleus upon them is weaker and more easily broken.