1. Atomic Structure & Electron Configuration
• Subatomic Particles:
o Proton: +1 charge, mass = 1
o Neutron: 0 charge, mass = 1
o Electron: -1 charge, negligible mass
• Shells and Subshells:
o Shells: Energy levels (n = 1, 2, 3…)
o Subshells: s, p, d, f – each has orbitals (s = 1, p = 3, d = 5)
o Each orbital holds 2 electrons with opposite spins (Pauli exclusion
principle)
• Aufbau Principle:
o Electrons fill lowest energy orbitals first:
1s → 2s → 2p → 3s → 3p → 4s → 3d → 4p...
• Electronic Configuration (e.g. Oxygen: 1s² 2s² 2p⁴)
Use noble gas shorthand (e.g. [Ne] 3s² 3p⁵ for Cl)
• Ionic Configurations:
o Cations lose electrons from the outermost shell.
o Transition metals lose from 4s before 3d.
2. Ionic Bonding
• Definition: Electrostatic attraction between oppositely charged ions.
• Formed Between: Metals (form cations) and non-metals (form anions)
• Structure: Giant ionic lattice – strong electrostatic forces in all directions.
• Properties:
o High melting and boiling points
o Conducts electricity when molten or in solution
o Soluble in polar solvents (e.g. water)
3. Covalent Bonding
• Definition: A shared pair of electrons between two non-metal atoms.
• Types:
o Single (e.g. H–H)
o Double (e.g. O=O)
o Triple (e.g. N≡N)
• Subatomic Particles:
o Proton: +1 charge, mass = 1
o Neutron: 0 charge, mass = 1
o Electron: -1 charge, negligible mass
• Shells and Subshells:
o Shells: Energy levels (n = 1, 2, 3…)
o Subshells: s, p, d, f – each has orbitals (s = 1, p = 3, d = 5)
o Each orbital holds 2 electrons with opposite spins (Pauli exclusion
principle)
• Aufbau Principle:
o Electrons fill lowest energy orbitals first:
1s → 2s → 2p → 3s → 3p → 4s → 3d → 4p...
• Electronic Configuration (e.g. Oxygen: 1s² 2s² 2p⁴)
Use noble gas shorthand (e.g. [Ne] 3s² 3p⁵ for Cl)
• Ionic Configurations:
o Cations lose electrons from the outermost shell.
o Transition metals lose from 4s before 3d.
2. Ionic Bonding
• Definition: Electrostatic attraction between oppositely charged ions.
• Formed Between: Metals (form cations) and non-metals (form anions)
• Structure: Giant ionic lattice – strong electrostatic forces in all directions.
• Properties:
o High melting and boiling points
o Conducts electricity when molten or in solution
o Soluble in polar solvents (e.g. water)
3. Covalent Bonding
• Definition: A shared pair of electrons between two non-metal atoms.
• Types:
o Single (e.g. H–H)
o Double (e.g. O=O)
o Triple (e.g. N≡N)
