General Chemistry for the MCAT

Atomic Structure & Periodic Trends

Electron configuration determines chemical behavior. The arrangement of electrons follows the Aufbau principle, filling lower energy orbitals first: 1s² 2s² 2p⁶ 3s² 3p⁶ 4s² 3d¹⁰...

Periodic Trends:

• Electronegativity: Increases across a period (left to right) and up a group
• Ionization Energy: Increases across a period and up a group
• Atomic Radius: Decreases across a period, increases down a group
• Effective Nuclear Charge (Zeff): Increases across a period

Chemical Bonding

• Ionic bonds: Transfer of electrons between metals and nonmetals
• Covalent bonds: Sharing of electrons between nonmetals
• VSEPR Theory: Predicts molecular geometry based on electron pair repulsion
• Hybridization: sp (linear), sp² (trigonal planar), sp³ (tetrahedral)

Acids, Bases & Buffers

Brønsted-Lowry: Acids donate H⁺, bases accept H⁺ Lewis: Acids accept electron pairs, bases donate electron pairs

$\text{pH} = -\log[\text{H}^+]$ $\text{Henderson-Hasselbalch: } \text{pH} = \text{p}K_a + \log\frac{[A^-]}{[HA]}$

Chemical Kinetics

$\text{Rate} = k[A]^m[B]^n$ $\text{Arrhenius: } k = Ae^{-E_a/RT}$

Catalysts lower activation energy without being consumed.