Electron Configuration and Atomic Orbitals

Electron Configuration

• The arrangement of electrons in an atom, which determines the chemical properties of an element
• Described by the Aufbau principle, Pauli's Exclusion Principle, and Hund's Rule
• Electron configuration is written in a shorthand notation, such as 1s2 2s2 2p6 for Ne (Neon)
• Energy levels (shells) are divided into subshells (s, p, d, f) with specific capacities
• Valence electrons are the outermost electrons involved in chemical bonding

Ionization Energy

• The energy required to remove an electron from an atom in its ground state
• Measured in kJ/mol (kilojoules per mole)
• Ionization energy increases:
  • Across a period (left to right) due to increasing nuclear charge
  • Down a group (top to bottom) due to increasing atomic size and shielding
• First ionization energy is the energy required to remove the first electron, subsequent ionization energies are for removing additional electrons

Atomic Orbitals

• A mathematical description of the distribution of electrons within an atom
• Orbital shapes: s (spherical), p (dumbbell), d (four-leaf clover), f (complex)
• Orbital types:
  • s orbitals: spherical, symmetrical, and can hold up to 2 electrons
  • p orbitals: dumbbell-shaped, oriented along x, y, and z axes, and can hold up to 6 electrons
  • d and f orbitals: more complex shapes, and can hold up to 10 and 14 electrons, respectively
• Orbitals are combined to form hybrid orbitals, which are used to describe molecular bonding and shape