Transcript fhs as 1.5 lesson3 cro filling orbitals and shells

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:
(a) Write the electronic configurations of the following atoms:
lithium, nitrogen and sulphur.
(b)
i. Write the electronic configuration of the following ions:
fluoride, lithium and oxide.
ii. What do you notice about the electronic configuration of
ions?
iii. Suggest why this is so.
(c) 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’
Each orbital can hold maximum of 2 electrons.
subshell has 5 orbitals, ‘f’ subshell has 7 orbitals.
What will be the maximum number of electrons
in each subshell and shell?
• Copy and complete the following table:
-
- -
- - -
- - - -
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, dx2- y2, dz2
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 2+
2-
2+
• Write the electronic configuration for O and Ca
Try Some Ions! (Grade A/A*)
• Write the longhand notation for these:
FLi+
Mg+2
• Write the shorthand notation for these:
BrBa+2
Al+3