What are Chemical Bonds?
Chemical bonds are the forces that hold atoms together to form molecules and compounds. They form when atoms share, transfer, or pool electrons to reach a more stable, lower-energy arrangement — usually a full outer electron shell.
A chemical bond is the attractive force between atoms caused by electron sharing (covalent), electron transfer (ionic), or a shared 'sea' of electrons (metallic), which lowers the overall energy of the system.
- •Electrons are transferred, not shared
- •Forms between a metal and a nonmetal
- •Creates charged ions (cation + anion)
- •High melting/boiling points
- •Conducts electricity when dissolved or molten
- •Example: NaCl (table salt)
- •Electrons are shared between atoms
- •Forms between two nonmetals
- •Creates discrete molecules
- •Lower melting/boiling points
- •Usually poor electrical conductor
- •Example: H₂O (water)
Step-by-step worked examples
Explain how sodium (Na) and chlorine (Cl) form an ionic bond in NaCl.
Na has 1 valence electron; Cl has 7 valence electrons Na transfers its 1 electron to Cl Na becomes Na⁺ (stable, full shell); Cl becomes Cl⁻ (stable, full shell) Opposite charges attract → ionic bond forms
Explain how two hydrogen atoms form a covalent bond in H₂.
Each H atom has 1 electron and needs 2 to fill its shell Both atoms share their single electrons in a shared pair The shared electron pair holds the atoms together → covalent bond
Classify the bond in MgO (magnesium oxide) and CO₂ (carbon dioxide).
MgO: magnesium (metal) + oxygen (nonmetal) → electrons transfer → ionic bond CO₂: carbon (nonmetal) + oxygen (nonmetal) → electrons shared → covalent bond
Flashcards
Quick quiz
Q1.A bond between a metal and a nonmetal, formed by electron transfer, is called…
Q2.In a covalent bond, electrons are…
Q3.Which best describes a metallic bond?
Q4.Which compound is held together by a covalent bond?
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Common mistakes
Thinking all bonds between atoms are ionic. — Correct: Bonds between two nonmetals are usually covalent; only metal–nonmetal pairs form ionic bonds.
Believing electrons disappear in an ionic bond. — Correct: Electrons aren't lost — they transfer from one atom to another, creating charged ions.
Assuming covalent compounds conduct electricity like ionic ones. — Correct: Covalent (molecular) compounds usually don't conduct electricity, since they have no free ions.
Mixing up 'sharing' and 'transferring' electrons. — Correct: Covalent bonds share electrons; ionic bonds transfer them completely.
FAQ
What are chemical bonds?
The forces — ionic, covalent, or metallic — that hold atoms together by sharing or transferring electrons.
What is the chemical bonds formula for predicting bond type?
Compare electronegativity: large differences (metal + nonmetal) give ionic bonds; small differences (nonmetal + nonmetal) give covalent bonds.
What are examples of chemical bonds?
NaCl (ionic), H₂O and CO₂ (covalent), and metallic copper or iron (metallic bonding) are classic examples.
How do you determine if a bond is ionic or covalent?
Metal + nonmetal → ionic; nonmetal + nonmetal → covalent. Large electronegativity differences favor ionic bonding.