5.1 electron structure Flashcards
what are they?
Electron shells
- Shells are regarded as energy levels
- Shells are a part of a model that helps scientists visualise an intangible object
- The energy increases as the shell number increases
- The shell number (or energy level number) is called the PRINCIPAL QUANTUM NUMBER, n
Confirming the maximum number of electrons in a shell is given by the formula:
number of electrons = 2n^2
(n = shell no. principal quantum number)
Electrons can have properties of both…
wave and a particle – wave-particle duality.
Orbital:
def: A region around the nucleus that can hold up to two electron, with opposite spins.
atomic orbitals.
shells are made up of atomic orbitals. an atomic orbitsl are regions around a nucleus and can hold up to two electrons
how many electrons are held in an orbital?
An orbital can hold one or two electrons, but no more.
what are the tyepes of orbitals?
There are different types of orbitals with different shapes:
s-orbital, p-orbital, d-orbital, f-orbital
what shape is the, how many electrons can be held
S-orbital
The electron cloud (orbital) is
spherical.
Like all orbitals, an s-orbital can
only hold 2 electrons
Each shell from n=1 contains
one s-orbital. The greater the
shell number, the greater the
radius of the s-orbital.
what shape is the, how many electrons can be held
P-orbital
The electron cloud (orbital) is a dumb bell shape.
Like the s-orbital, each orbital can only hold 2
electrons
There are three separate p-orbitals, all at right
angles to each other: Px Py Pz
Each shells from n=2 contains THREE
p=orbitals
The greater the shell number n, the further
the p-orbital from the nucleus
Within a shell, orbitals of the same type are grouped together as…..
SUB-SHELLS.
(simply put; subshells are divided into orbitals)
and whats the name of this principle
How do orbitals fill?
Each sub-shell has a different amount of energy associated with them. Orbitals fill in order of
increasing energy. Lowest energy sub-shells fill first.
This is known as the Aufbau principle.
whats the anomoly with filling orbitals
4s is lower in energy than 3d, therefore fills first.
however once filled 3d falls belllow 4s energy level hence it empties first too
what are the two elements with differnet electron configurations?
- chromium
- copper
what is the electron configuration of
chromium
Cr 1s2 . 2s2 . 2p6 . 3s2 . 3p6** . 4s1 . 3d5**
This gives a half filled 3d sub-shell: greater stability on the arrangement of electrons.
what is the electron configuration of
Copper
Cu: 1s2 . 2s2 . 2p6 . 3s2 . 3p6 . 4s1 . 3d10
This gives a fully filled 3d sub-shell which imparts a greater amount of stability on the arrangement of electrons.
Representation of electronic configuration - shorthand:
We can shorten the electronic
configuration and write it in terms of the nearest (previous) noble gas. eg.[Ne]3s2
hunds rule
The pairing of electrons:
Electrons prefer to occupy orbitals on their own, and only pair up when no empty orbitals of the
same energy are available. They prefer to occupy each orbital singly to minimise repulsion of
electron charges.
Each orbital can hold 2 electrons of opposite spin.
(they idea of spin comes from whether they will or will not align with a magnetic field)
How many orbitals in the
S- sub shell
P - sub shell
D- sub shell
F- sub shell
1 S- sub shell (2 e-)
3 P - sub shell (6e-)
5 D- sub shell (10e-)
7 F- sub shell (14e-)
