Quantum Mechanics: What are the electron energies? Bohr Model Quantum Mechanical Model (High P.E.) 3d 3p n=3 3s 2p n=2 2s n=1 1s (Low P.E.)

Factors that affect electron energies: Orbital Size p+ e- Hydrogen Atom p+ 1s orbital e- Hydrogen Atom Remove the electron and compare! 1s 2s High P.E. Low P.E. ... e- closer to nucleus ...e- further from nucleus ... greater e- ... p+ attraction ... weaker e- ... p+ attraction ... harder to remove e- ... easier to remove e- ... lower energy e- ... higher energy e-

Factors that affect electron energies: Additional e- Neutral Helium Atom He+ Cation The first electron removed from an orbital has higher P.E. than the second electron removed from the same orbital. 2p+ 1s orbital e- Remove the electron and compare! 2p+ e- 1s orbital ...electrons are the same distance from nucleus ...1 electron attracted by nucleus ...2 electrons repel each other ...no electron-electron repulsion ... electron easier to remove ... electron harder to remove ... higher energy e- ... lower energy e-