3: Filling orbitals and shells f. describe the shapes of electron density plots (or maps) for s and p orbitals g. predict the electronic structure and configuration of atoms of the elements from hydrogen to krypton inclusive using 1s …notation and electron-in-boxes notation (recall electrons populate orbits singly before pairing up) Connector – use the 1s2 … notation to: Write the electronic configurations of the following atoms: lithium, nitrogen and sulphur. Write the electronic configuration of the following ions: fluoride, lithium and oxide. What do you notice about the electronic configuration of ions? Suggest why this is so. Identify the following atoms:

Write the electronic configuration of the following ions: Ions have the electronic configuration of the STABLE NOBLE GASES.

Arrangement of Electrons in Atoms Electrons in atoms are arranged as SHELL (n) SUBSHELLS ORBITALS Each type of subshell (s,p,d,f) contains one or more orbitals. An Orbital represents the region in space where it is most likely to find an electron.

Shells, subshells and orbitals ‘s’ subshell has 1 orbital, ‘p’ subshell has 3 orbitals, ‘d’ subshell has 5 orbitals, ‘f’ subshell has 7 orbitals. Copy and complete the following table: Each orbital can hold maximum of 2 electrons. What will be the maximum number of electrons in each subshell and shell? - - - - - - - - - -

Energy level diagram As the principal quantum number ‘n’ increases, the energy gap between successive shells decreases. As a result, neighbouring subshells overlap and have a different order of increasing energy in subshells.

Shapes of Orbitals Orbitals have different shapes is an area of zero probability of finding an electron

Home Learning Research task Use The Heisenberg Uncertainty Principle to explain the impossibility of drawing orbits for electrons. i.e. Why is this wrong? But this is correct? Due date: Next Lesson

Shapes of p Orbitals p sublevel has 3 orbitals – px,py,pz There is a PLANAR NODE thru the nucleus, which is an area of zero probability of finding an electron

Shapes of d Orbitals d sublevel has 5 orbitals – dxy, dxz, dyz, dx - y, dz 2 2 2

* Pauli exclusion principle Filling the orbitals An atom is in it’s lowest energy state (ground state) when it’s electrons are in the orbitals with the lowest possible energy level. One of the factors influencing the filling of orbitals is Electron spin. An electron can either have clockwise or anticlockwise spin. Two electrons in the same orbital MUST have opposite spin*. Represented by: * Pauli exclusion principle

Filling the orbitals Copy and complete the table by filling the correct number of orbitals with electrons.

Rules for filling the orbitals Electrons will fill the lowest energy orbital first, then the remaining number of orbitals with increasing energy. Hund's Rule - Electrons occupy all the orbitals of a given sublevel singly before pairing begins. Spins of electrons in different incomplete orbitals are parallel in the ground state. The most stable arrangement of electrons in the subshells is the one with half filled or completely filled orbitals.

Complete the orbital diagram from H to Ne Hund's Rule - Electrons occupy all the orbitals of a given sublevel singly before pairing begins. Spins of electrons in different incomplete orbitals are parallel in the ground state.

Complete the electronic configuration and orbital diagram from O to Ar. 1s 2s 2p Hund’s rule This is called Shorthand notation

Complete the electronic configuration and orbital diagram from K to Cr.

Complete the electronic configuration and orbital diagram from Mn to Kr.

ELECTRON CONFIGURATIONS OF IONS For an ion, you simply add or subtract the right number of electrons from the outermost shell – taking electrons for a positive ion and adding electrons for a negative ion. For example, write the electronic configuration for V and then for V Write the electronic configuration for O and Ca 2+ 2- 2+

Try Some Ions! (Grade A/A*) Write the longhand notation for these: F- Li+ Mg+2 Write the shorthand notation for these: Br- Ba+2 Al+3