6 - electronic structure

An energy level which electrons are arranged in The further away the shell from the nucleus, the higher the energy level

The principal quantum number The fourth shell has a principal quantum number of n = 4

A region within an atom which can hold up to 2 electrons which will have opposite spins

The direction in which an electron spins An electron can spin up or spin down when an electron is al

Oppositely spinning electrons pair up naturally in order to reduce repulsion

A pair of electrons in an orbital: A square representing the orbital One up arrow and then a down arrow to the right of it to represent the 2 opposite spin electrons -fill up spins first, when only 1 electron it has an up spin

S-orbitals P-orbitals D-orbitals F-orbitals

It has a spherical shape Every shell has a single S-orbital S-orbitals provide space for 2 electrons in each shell

It has a dumbbell shape (3D) There is one P-orbital per axis per shell So there is 3 P-orbitals per shell (X, Y and Z axis) There is one set of 3 P-orbitals in every shell after n = 2 A set of P-orbitals provides space for 6 electrons (3 spin pairs)

There are 5 D-orbitals per shell meaning they provide space for 10 electrons per shell There is one set of 5 D-orbitals in every shell after n = 3

7 orbitals per shell Space for 14 electrons per shell One set of 7 F-orbitals per shell after n = 4

Take the principal quantum number Square it Double it That’s the number of electrons in that shell

A group of the same type of orbitals within a shell E.g the D sub-shell is the 5 sets of orbitals in one shell

They go into the lowest shell possible They go into the smallest sub-shell possible (S first and F last) They spread out as much as possible between the different orbitals in a sub-shell

The principal quantum number then the orbital type then the number of electrons in that sub-shell is superscripted Then do the same for the next sub-shell You write the lowest energy sub-shell first and the highest last E.g If there is 7 electrons: There is 2 electrons in the n = 1 S orbital Written as: 1s^2 There is 2 electrons in the n = 2 S orbital Written as: 2s^2 There is 3 electrons in the n=2 P orbital Written as 2p^3 The entire electronic configuration is: 1s^2 2s^2 2p^3

Just write the symbol of the noble gas in brackets

1s^2 2s^2 2p^6 3s^2 3p^6 4s^2 3d^8 or [Ar] 4s^2 3d^8 4s has a lower energy level than 3d so 4s is actually filled up before 3d is

If the charge is 2-, add 2 electrons If the charge is +, take away an electron Use this number of electrons to calculate the electronic configuration

3 electrons in lithium atom Charge is + 2 electrons in Li + So the electronic configuration is 1s^2 Abbreviated to (He)

Calculate the configuration of the base atom first Take away the electrons from the configuration to make the ion after Take away electrons from the outer shell first E.g (Ar) 4s^2 3d^1 You need to take 2 electrons You take them from 4s because of the nature of reactions So the ion’s configuration is (Ar) 3d^1

Hydrogen and helium only have 1s orbital The block on the left of the table (group 1 and 2) is the S-block and all electronic configuration end in an S orbital here The transition metals is the D-block and all configurations in here end in a D orbital The block on the right is the P-block where all inside end in a P orbital The block separated at the bottom is the F-block (lanthanides, actinides), all of these end in an F orbital