Question

3.4 electron configurations
define
electron configuration
pauli exclusion principle
aufbau principle
hund’s rule
core electrons
valence electrons
energy diagram

Explanation:

1. Electron Configuration: Describes the arrangement of electrons in an atom's orbitals, following specific rules to minimize energy.
2. Pauli Exclusion Principle: No two electrons in an atom can have identical sets of all four quantum numbers; each orbital holds max 2 electrons with opposite spins.
3. Aufbau Principle: Electrons fill lower-energy orbitals first before occupying higher-energy ones, following the order shown in the energy diagram.
4. Hund's Rule: When filling degenerate orbitals (same energy), electrons occupy separate orbitals with parallel spins first before pairing up.
5. Core electrons: Inner-shell electrons that are not involved in chemical bonding; they are in filled, lower-energy orbitals.
6. Valence electrons: Outer-shell electrons in the highest energy level, responsible for an atom's chemical properties and bonding behavior.

Answer:

1. Electron Configuration: The specific arrangement of electrons in the atomic orbitals of an atom or ion.
2. Pauli Exclusion Principle: No two electrons in a single atom can have the same four quantum numbers; each orbital can hold at most 2 electrons with opposite spin states.
3. Aufbau Principle: Electrons occupy the lowest-energy atomic orbitals first before filling higher-energy orbitals.
4. Hund's Rule: For degenerate orbitals (equal energy), electrons occupy each orbital singly with parallel spins before any orbital gets a second electron.
5. Core electrons: The inner electrons of an atom that are not in the outermost valence shell and do not participate in chemical reactions.
6. Valence electrons: The electrons in the outermost occupied shell of an atom that determine the atom's chemical reactivity and bonding potential.