Module 3 Flashcards
Penetration
A measure of how close a particular electron gets to the nucleus.
Shielding
How thoroughly a particular electron is blocked (or shielded) from the nucleus.
n
Shell (1 —> ∞).
l
Subshell (0 —> n-1).
Energetically Degenerate Orbitals
When the energy for different subshells at a given shell is the same (only occurs in H atoms).
The Pauli Exclusion Principle
No two electrons can have the same set of quantum numbers n, l, ml, and ms.
The Aufbau Procedure
For neutral atoms, orbitals are filled according to the n + l rule.
Hund’s Rule
If there are not enough electrons to fill completely a set of energetically degenerate orbitals, the lowest energy arrangement is the one which has the maximum number of parallel spins.
Valence Electrons
Electrons in the outermost shell of an atom. They are the electrons that participate in bond formation.
Diamagnetic Atoms
All electrons are paired, the atom does not possess a magnetic moment. The atom interacts only weakly with an external magnetic field.
Paramagnetic Atoms
One or more unpaired electrons, the atom possesses a magnetic moment. The atom interacts strongly with an external magnetic field.
Covalent Radius
1/2 of the diatomic bond length for the X2 molecule (of X). Useful for elements that form diatomic molecules.
Metallic Radius
1/2 of the distance between “nearest neighbours” in a metallic solid. Useful for elements that are metals.
Ionization Energy (IE)
The energy required to remove an electron from a gas-phase atom. Often reported as an enthalpy change, ΔH.
Electron Affinity (EA)
The energy change that accompanies the addition of an electron to a gas-phase atom. Can be positive or negative.
