MTL 200 Chapter Notes - Chapter 2: Pauli Exclusion Principle, Valence Electron, Aufbau Principle

• School: Ryerson University
• Department: Mechanical Engineering
• Course: MTL 200
• Professor: Alan Mac Hin

Document Summary

Atomic number = number of protons and electrons in nucleus. Aufbau principle - electrons occupy the lowest energy orbital before entering higher energy orbitals. Hund principle - orbitals of equal energy orbital are occupied by a single electron before electron of opposite spin can occupy it. Pauli exclusion principle - no more than two electrons can occupy the same energy level and these two must have opposite spins (they must have different quantum numbers) Electrons have discrete energy states and tend to occupy lowest available energy state. Valence electrons tend to control chemical properties. Ionic - metal (donates electrons) + nonmetal (accepts electrons), large difference in en required, electrons transfer. Covalent bonding - share electrons, similar en, can occur between as few as two atoms.