5.1 electron structure

Question 1

what are they?

Electron shells

Answer 1

• 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

Question 2

Confirming the maximum number of electrons in a shell is given by the formula:

Answer 2

number of electrons = 2n^2
(n = principal quantum number)

Question 3

Electrons can have properties of both…

Answer 3

wave and a particle – wave-particle duality. Electrons fit
into an energy level around an atom defined by the wave nature of an electron.

Question 4

Orbital:

Answer 4

def: A region around the nucleus that can hold up to two electron, with opposite spins.

Question 5

atomic orbitals.

Answer 5

Shells, where the electrons are found, are made up of different types of

Question 6

how many electrons are held in an orbital?

Answer 6

An orbital can hold one or two electrons, but no more.

Question 7

what are the tyepes of orbitals?

Answer 7

There are different types of orbitals with different shapes:

s-orbital, p-orbital, d-orbital, f-orbital

Question 8

what shape is the, how many electrons can be held

S-orbital

Answer 8

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.

Question 9

what shape is the, how many electrons can be held

P-orbital

Answer 9

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

Question 10

Within a shell, orbitals of the same type are grouped together as…..

Answer 10

SUB-SHELLS.

(simply put; subshells are divided into orbitals)

Question 11

and whats the name of this principle

How do orbitals fill?

Answer 11

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.

Question 12

whats the anomoly with filling orbitals

Answer 12

4s is lower in energy than 3d, therefore fills first. And therefore 3d emptys before 4s

Question 13

what are the two elements with differnet electron configurations?

Answer 13

• chromium
• copper

Question 14

what is the electron configuration of

chromium

Answer 14

Cr 1s2 . 2s2 . 2p6 . 3s2 . 3p6** . 4s1 . 3d5**

This gives a half filled 3d sub-shell: greater stability on the arrangement of electrons.

Question 15

what is the electron configuration of

Copper

Answer 15

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.

Question 16

Representation of electronic configuration - shorthand:

Answer 16

We can shorten the electronic
configuration and write it in terms of the nearest (previous) noble gas. eg.[Ne]3s2

Question 17

hunds rule

The pairing of electrons:

Answer 17

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)

Question 18

How many orbitals in the

S- sub shell
P - sub shell
D- sub shell
F- sub shell

Answer 18

1 S- sub shell (2 e-)
3 P - sub shell (6e-)
5 D- sub shell (10e-)
7 F- sub shell (14e-)