01Electronegativity decides
Bonds sit on a spectrum. Equal sharing between identical nonmetals is nonpolar covalent. Unequal sharing is polar covalent. A metal + nonmetal with a large electronegativity difference forms an ionic bond.
Metallic bonding is a sea of delocalized electrons around metal cations.
02Notebook box
ΔEN ≈ 0 nonpolar · 0.4–1.8 polar · large / metal+nonmetal ionic.
Worked example: Rank by polarity: H–F, H–Cl, H–Br → H–F is most polar (F most electronegative).