Ionic vs Covalent Bonds: How Atoms Join Together
Atoms join to form compounds because a full outer shell of electrons is more stable. The way they get there decides the type of bond.
Ionic bonds: transferring electrons
An ionic bond forms when one atom gives electrons to another. This usually happens between a metal and a non-metal. The atom that loses electrons becomes positively charged; the one that gains them becomes negative. Opposite charges attract, holding them together. Table salt (sodium chloride) is the classic example.
Covalent bonds: sharing electrons
A covalent bond forms when two atoms share electrons instead of transferring them. This typically happens between non-metals. Water (H₂O) and carbon dioxide (CO₂) are held together by covalent bonds.
Telling them apart
A quick checklist for exam questions.
- •Metal + non-metal → usually ionic (electrons transferred).
- •Non-metal + non-metal → usually covalent (electrons shared).
- •Ionic compounds often dissolve in water and conduct electricity when molten or dissolved.
Frequently asked questions
What is the difference between ionic and covalent bonds?
Ionic bonds transfer electrons between atoms; covalent bonds share electrons between atoms.
Is salt ionic or covalent?
Sodium chloride (table salt) is ionic — sodium gives an electron to chlorine.