Periodictable - Questions

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Same except for orientation in space

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Same except for orientation in space

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Electron spin

Each orbital can hold at most two electrons. Electrons also have spin (turning on an axis) and have magnetic properties (deflected in magnetic field). Electrons in the same orbital must have opposite spins. If they have opposite spins the electrons are said to be paired.

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What to do with all this info?

Rules for writing electron configuration:

1. The no. of electrons in neutral atom = atomic no. (no. of protons)

2. Fill the lowest energy sublevel completely, then the next lowest, etc.

3. No more than two electrons can be placed in a single orbital. The electrons have opposite spins in the same orbital. (2 electrons in s, 6 in p, 10 in d, 14 in f)

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4. For n=1,

For n =2

For n=3,

For n=4,

Remember the order of filling as follows:

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How to remember the energy order

1s

2s 2p

3s 3p 3d

4s 4p 4d 4f

5s 5p 5d 5f 5g

6s 6p 6d 6f 6g 6h

7s 7p 7d 7f

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Let’s do some electron configurations

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Abbreviated electron configuration

2He 1s2

10Ne 1s22s22p6

18Ar 1s22s22p63s23p6

36Kr 1s22s22p63s23p64s23d104p6

These configurations are for ground state configurations--lowest energy.

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Valence electrons

, p 59

Valence electrons are the electrons located in the _ orbitals and are the ones involved in forming chemical bonds. The valence electrons have the largest _ value for the A elements.

For representative elements the number of valence electrons in an atom =

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Don’t worry about inner core of electrons (smaller n) since these are filled levels and don’t enter into bond formation ( for A groups)

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Valence electron configuration for A groups

Group IA

Group IIA

Group IIIA

Group IVA

Group VA

Group VIA

Group VIIA

Group VIIIA