Electron Arrangement:

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Electron Arrangement

• electrons (e) are found in energy levels outside
  of the nucleus.
• Energy level(s) Orbit(s) or Shell(s) where e
  are found.
• (a.k.a. Principal Energy Level(s))

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• Period Horizontal (left ? right) row in the
  periodic table.
• Period the of occupied energy levels
  (E.L.)
• Q How many periods are there on the periodic
  table???

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There are a total of 7 possible E.L.

• 1st Energy level (1st E.L.) closest to nucleus.
• has LEAST energy of all E.L.
• 7th E.L. has MOST energy of all E.L.

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• e only occupy the orbits of lowest E.L. first.
• Eg. e fill up 1st E.L. ? fill up 2nd E.L. ?.
  . . ? fill up 7th E.L.

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Formula for of e allowed in each E.L.

• n E.L.
• (Eg. n 6 ? 6th E.L.)
• 2n2 of e that can occupy E.L. n.

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Q.1. How many e can occupy E.L. 1?
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Q.2. Fill in the following Table. (show work on
the side)
Energy level (n) max. of electrons allowed (2n2)
1 2
2
3
4
5
6
7
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Octet Rule

• Octet Rule The valence E.L. can never hold more
  than 8 e-.
• Valence E.L. outermost shell
• Valence electrons electrons on the valence
  (outermost) shell.

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Octet Rule (contd)

• All Elements WANT to have a FULL valence energy
  level (shell)
• Full valence shell 8 e- (or 2 e- if 1st E.L.)
• H and He only want 2 valence electrons
• Why???

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Octet Rule (Contd)

• Eg. draw the Bohr model of potassium-38 (38K)
• Q.1) How many valence e- does K have?
• Q.2) How many valence e- does K want?
• Q.3) What is the easiest (least energy) way for K
  to obtain this???
• Energy Levels

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Electron Configuration

• Electron Configuration The of electrons
  according to the shell theyre in.
• Write out the of e- according to the shell
  theyre in.
• Eg. H Li
• Electron Config. Electron Config.

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Symbol Electron Config. Symbol Electron Config.
1 11
2 12
3 13
4 14
5 15
6 16
7 17
8 18
9 19
10 20
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Ground State vs. Excited State

• Ground State and Excited State
• refers to the state of the atom based on location
  of electrons.

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Ground State

• Ground State
• Electrons occupy LOWEST E.L. (Energy Levels).
• LOW Energy
• STABLE
• 
  Why???
• P.T. shows ground state only!!!

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Excited State

• Excited State
• Electron jumps to HIGHER energy level
  (temporarily)

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Excited State

• jump up ? ABSORBS energy
• sugar high
• fall down ? RELEASES energy (as LIGHT!)
• sugar low
• UNSTABLE
• HIGH Energy
• Exciting an electron

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Excited State

• Drawing of atom in the excited state

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Excited State

• Flame Test
• Formed by the heating of metal ions, using a
  flame.
• Demo Flame Tests (Cu, Li, K, Na, Sr)
• Q.) Why does the flame cause this effect?

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Excited State

• Spectral Lines the DNA code of elements
• Formed by Gases (must use electricity)
• Spectral lines
• Demo Spectral lines
• must use 3-D glasses.

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Excited State Spectral Lines

• Q. Based on the line spectra, which of the
  following elements are contained in the unknown
  sample?

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Excited vs. Ground State

• Label each of the following as being in the
  ground state or excited state
• (see if you can convert excited ? ground)
• A.) 2-8-1
• B.) 1-8
• C.) 2-8-7-1
• D.) 2-7-5
• E.) 2-8-18-5

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Electron Dot Diagram

• Electron Dot Diagram
• Illustrates the element symbol surrounded by the
  valence electrons.
• Eg.1. Draw the Electron Dot Diagram
• H C Ca

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Electron-dot Diagrams (contd)

• Ne B N Ba
• S F Hg Cl

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Groups

• Groups
• Vertical (up and down) columns on the P.T.
• Q. What do elements in the same group have in
  common???