(N/A) Electrovalent (ionic) bond: The bond formed as a result of the electrostatic attraction between positive and negative ions is termed as an electrovalent bond.
Example-$1$: Ionic bond formation in sodium chloride $(NaCl)$.
$Na$ (alkali metal) is a highly electropositive metal and forms a $Na^{+}$ ion by the loss of one electron to attain a stable noble gas electronic configuration.
$Na ([Ne] 3s^{1}) \longrightarrow Na^{+} ([Ne]) + e^{-}$
Chlorine is a highly electronegative halogen. It converts into a $Cl^{-}$ negative ion by gaining the electron lost by the sodium atom. This $Cl^{-}$ ion attains the stable electron configuration of the noble gas $Ar ([Ne] 3s^{2} 3p^{6})$.
$Cl ([Ne] 3s^{2} 3p^{5}) + e^{-} \longrightarrow Cl^{-} ([Ar] \text{ or } [Ne] 3s^{2} 3p^{6})$
Example-$2$: Ionic bond (electrovalent) formation in $CaF_{2}$.
Calcium loses two electrons to attain the stable noble gas configuration of argon and is converted into a $Ca^{2+}$ ion.
$Ca ([Ar] 4s^{2}) \longrightarrow Ca^{2+} ([Ar]) + 2e^{-}$
Fluorine is a highly electronegative halogen atom that gains one electron to achieve a stable outer shell configuration,converting into a fluoride ion.
$F ([He] 2s^{2} 2p^{5}) + e^{-} \longrightarrow F^{-} ([He] 2s^{2} 2p^{6} \text{ or } [Ne])$
The positive $Ca^{2+}$ ion and two negative $F^{-}$ ions are held together by strong electrostatic forces of attraction to form the electrovalent compound $CaF_{2}$.
$Ca^{2+} + 2F^{-} \longrightarrow CaF_{2}$