Transcript Electron Configuration 2

Electron
Configuration 2
Revision
spdf Notation
Author: J R Reid
Revision – Electron Shells
In a previous section we saw that the
shells of an atom get filled up from
the inside outwards. 2,8,8, was the
rule.
Now we are going to modify that
slightly. We are going to call those
shells energy levels and there are
going to be sub-levels within each
level
Energy Levels
Each ‘shell’ (or
‘level’) of
electrons can
be divided
into sub shells
Level 1 has
one sub-shell
only
Level 2 has
two
Level 3 has
three
spdf - Notation
The sublevels are given letters as names:
S – is the first and it can have 2 electrons
P – is the second and it can fit 6 electrons
D – is the third and it can fit 10 electrons
We never seem to get up to F but it can fit 14
electrons
The first level is small so it can fit only one
sublevel, the second is bigger so it can fit
two, the third can fit three…and so on
Writing Electron
Cofigurations
When we write the electron
configurations we need to
note the energy level, the
sublevel and how many
electrons are in each level
e.g. Nitrogen has 7
electrons:
1s2 2s2 2p3
The first number is the
Level, the letter is the
sublevel and the superscript
is the number of electron
per sublevel
Unfortunately its not as
easy as just working your
way across the rows
Level
Sublevels
1
s2
2
s2
p6
3
s2
p6
d10
4
s2
p6
d10
f14
Working Out The Sublevels
Instead of filling up from
left to right across the table
we need to follow some
arrows. Start from the top
one and work your way
through. For example: Na
(11 electrons)
1s2 2s2 2p6 3s1
This seems to the same as
going from left to right but
thing go funny with larger
atoms such as Sc (21
electrons)
1s2 2s2 2p6 3s2 3p6 4s2 3d1
As you can see the 4s got
filled before the 3d was
started
Level
Sublevels
1
s2
2
s2
p6
3
s2
p6
d10
4
s2
p6
d10
f14
What’s The Point?
These sublevels are important because
they help to explain why some
elements can form different types of
ions
Normally atoms lose or gain electrons
to fill or remove Levels/shells of
electrons. They also lose or gain
electrons to fill or remove sublevels.
More will be covered on this topic in
the Transition Metals section
Exam Practice - 2006
Have a go at Questions:
•
•
Can’t see the exam paper below?
Go to the NCEA website and
search for 90780
Exam Practice - 2007
Have a go at Questions:
•
•
Can’t see the exam paper below?
Go to the NCEA website and
search for 90780