Ionic bonds are formed between elements that have a significant difference in electronegativity. Electronegativity is the ability of an atom to attract electrons towards itself in a chemical bond. In an ionic bond, one atom completely transfers electrons to another, resulting in the formation of positively charged ions (cations) and negatively charged ions (anions).

1. Sodium and chlorine: Sodium (Na) has one valence electron and wants to lose this electron to achieve a stable electron configuration. Chlorine (Cl) has seven valence electrons and wants to gain one electron to achieve a stable configuration. When sodium and chlorine combine, sodium donates its electron to chlorine, resulting in the formation of Na+ and Cl- ions. The attraction between the oppositely charged ions forms an ionic bond.

2. Carbon and hydrogen: Carbon (C) and hydrogen (H) have similar electronegativities and tend to share electrons rather than transfer them. Carbon and hydrogen typically form covalent bonds by sharing electrons.

3. Chlorine and chlorine: Chlorine (Cl) has seven valence electrons and wants to gain one electron to achieve a stable configuration. When two chlorine atoms combine, they share electrons to achieve a stable configuration. This results in the formation