2.2 : Electrons, bonding and structure - shells, orbitals, sub-shells and energy levels Flashcards
Define principle quantum number
A number representing the relative overall energy of each orbital, which increases with distance from the nucleus.
Define energy level
An energy level/shell is a group of atomic orbitals with the same principle quantum number.
What is an orbital?
An orbital is a region within the atom that can hold up to 2 electrons with opposite spins.
What are the 4 different types of orbital?
s, p, d and f
What shape is each of the orbitals?
S-orbitals have a spherical shape.
P-orbitals have a 3D dumb-bell shape.
How many orbitals make up each of the sub-shells?
From n=1 upwards, each shell contains 1 s-orbital.
From n=2 upwards, each shell contains 3 p-orbitals, at right angles to each other.
From n=3 upwards, each shell contains 5 d-orbitals.
From n=4 upwards, each shell contains 7 f-orbitals.
Which sub-shells are filled first?
The lowest available energy level, closest to the nucleus.
What is meant by ‘electron configuration’?
The electron configuration is the arrangement of electrons in an atom/ion.
Why does the 4s sub-shell filled before the 3d sub-shell?
The 4s sub-shell is at a slightly lower energy level than the 3d sub-shell.
Which electron is removed first during ionisation?
The electron in the highest energy position.
Each occupied sub-shell is written in the form N X y, what do each of these letters represent?
N = shell number
X = type of orbital
y = number of e- in the orbitals making up the sub-shell
Why are orbitals filled singly before pairing starts?
Due to the repulsion of the negative charges between electrons, it requires less energy to occupy orbitals of the same energy singly than to pair electrons with opposing spins in an orbital.
