Electron Configuration 2

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# Electron Configuration 2 - PowerPoint PPT Presentation

Electron Configuration 2. Revision spdf Notation. 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.

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## Electron Configuration 2

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### Electron Configuration 2

Revision

spdf Notation

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
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
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

Can’t see the exam paper below?

Go to the NCEA website and search for 90780

• Have a go at Questions:
Exam Practice - 2007

Can’t see the exam paper below?

Go to the NCEA website and search for 90780

• Have a go at Questions: