⚡ Ionic Bonds
Understanding ionic bonding and electron transfer
What are Ionic Bonds?
Ionic bonds form when one atom transfers electrons to another atom, creating oppositely charged ions that are attracted to each other by electrostatic forces. This type of bonding typically occurs between metals and nonmetals.
Main Idea: Ionic bonds involve complete transfer of electrons from one atom to another, creating ions.
How Ionic Bonds Form
Step 1: Electron Transfer
- • Metal atom loses electron(s)
- • Nonmetal atom gains electron(s)
- • Creates positive and negative ions
Step 2: Ion Formation
- • Cation: positively charged ion
- • Anion: negatively charged ion
- • Ions have stable electron configurations
Step 3: Electrostatic Attraction
- • Opposite charges attract
- • Forms ionic compound
- • Strong electrostatic forces
Example: Sodium Chloride (NaCl)
Sodium (Na)
- • Group 1 alkali metal
- • Has 1 valence electron
- • Loses 1 electron to become Na⁺
- • Achieves noble gas configuration
Chlorine (Cl)
- • Group 17 halogen
- • Has 7 valence electrons
- • Gains 1 electron to become Cl⁻
- • Achieves noble gas configuration
The electrostatic attraction between Na⁺ and Cl⁻ forms the ionic compound NaCl (table salt).
Properties of Ionic Compounds
High Melting Points
Strong electrostatic forces require high temperatures to break the ionic bonds.
Example: NaCl melts at 801°C
Electrical Conductivity
Conduct electricity when dissolved in water or melted (ions are free to move).
Solid state: poor conductor
Solubility in Water
Most ionic compounds are soluble in water due to water's polar nature.
Water molecules surround ions
Brittle Solids
Ionic compounds are hard but brittle due to the arrangement of ions.
Crystal lattice structure
Crystal Structure
Ions arrange in regular, repeating patterns called crystal lattices.
Ordered arrangement
High Boiling Points
Strong ionic bonds require high temperatures to vaporize the compound.
Example: NaCl boils at 1413°C
Ionic Bonding Patterns
Group 1 + Group 17
Alkali metals (Group 1) react with halogens (Group 17) to form 1:1 ionic compounds.
Group 2 + Group 16
Alkaline earth metals (Group 2) react with chalcogens (Group 16) to form 1:1 ionic compounds.
Polyatomic Ions
Some ionic compounds contain polyatomic ions (groups of atoms with a charge).
Lattice Energy
Lattice energy is the energy released when gaseous ions combine to form an ionic solid. It's a measure of the strength of ionic bonds.
Factors Affecting Lattice Energy:
Ion Charge
- • Higher charges = stronger attraction
- • Mg²⁺O²⁻ stronger than Na⁺Cl⁻
- • Charge affects lattice energy significantly
Ion Size
- • Smaller ions = stronger attraction
- • Closer ions have stronger forces
- • Size inversely affects lattice energy
Ionic vs Covalent Bonding
Ionic Bonds
- • Complete electron transfer
- • Metal + nonmetal
- • High melting/boiling points
- • Conduct electricity when dissolved
- • Form crystal lattices
- • Example: NaCl, MgO
Covalent Bonds
- • Electron sharing
- • Nonmetal + nonmetal
- • Lower melting/boiling points
- • Poor electrical conductors
- • Form discrete molecules
- • Example: H₂O, CO₂
Lazy Read
- • Ionic bonds form through complete electron transfer
- • Metals lose electrons to become cations (+)
- • Nonmetals gain electrons to become anions (-)
- • Electrostatic attraction holds ions together
- • Ionic compounds have high melting/boiling points
- • They conduct electricity when dissolved or melted
- • Most are soluble in water and form crystal structures