Energy levels, sub-levels and orbitals Flashcards
Formula for maximum number of electrons an energy level can hold
2n^2
Max no. of electons in s sub-level
2
Max number of electrons in p sub-level
6
Max number of electrons in d sub-level
10
Max number of electrons in f sub-level
14
What are the two elements that are exceptions in electron configurations?
Chromium and copper
Electron configuration for chromium
[Ar] 4s¹ 3d⁵
Electron configuration for copper
[Ar] 4s¹ 3d¹⁰
What does an element’s block on the periodic table (s,p,d or f) tell us about its valence electrons
Elements in a particular block have their valence electrons in the sub-level indicated by the block
No. of orbitals in s sub-level
1
No. of orbitals in p sub-level
3
No of orbitals in d sub-level
5
No. of orbitals in f sub-level
7
Aufbau principle
In an atom or ions groud state, electrons fill up the lowest energy sub-levels before filling up higher energy sub-levels
Hund’s rule
In a sub-level, every orbital must be singly occupied with one electron before any can be doubly occupied with two electrons.
All electrons in singly occupied orbitals have the same spin
Pauli exclusion principle
An orbital can have a maximum of two electrons, and two electrons in the same orbital must have opposite spins
How does spin manifest itself?
In the tendency of electrons to move away/in opposite directions from each other
Ionisation energy
Energy required to remove one mole of electrons from one mole of gaseous atoms
3 factors affecting ionisation energy
Number of protons
Energy of the electron being removed - its energy level
Electron shielding - electrons beteween valence electrons and nucleus
What happens when an atom moves ground state to n = ∞ ?
It is removed from the atom, forming an ion
What line represents ionisation energy on an emission spectrum?
Line with lowest wavelength and highest frequency
