When a very electronegative atom strips a valence electron away from its partner, form?

Explanation:

When there occurs sharing of electrons between two chemically combining atoms then it tends to form a covalent bond.

As, atomic number of hydrogen is 1 and its electronic configuration is .  

Hence, in order to become stable in nature it will reaction share its valence electron with another atom.  

As atomic number of chlorine is 17 and its electronic distribution is 2, 8, 7. So, in order to attain stability it will readily react a hydrogen atom who also wants to become stable.

As a result, HCl compound will be formed which is a covalent compound.

Whereas when an electron is being donated by an atom to another atom then it results in the formation of an ionic bond.

For example, sodium has one valence electron and chlorine has 7 valence electron.

Hence, chlorine being more electronegative in nature will attract the valencxe electron of sodium towards itself. Hence, an ionic compound NaCl will be formed.

Thus, we can conclude that when a very electronegative atom strips a valence electron away from its partner, an ionic compound forms.

it's c. elements are placed in rows based on how may valencies electrons have.