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## PowerPoint Slideshow about ' Dmitri Mendeleev' - stian

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Dmitri Mendeleev

- Arranged elements by increasing atomic mass
- Predicted properties of missing elements

Episode 401

Henry Moseley

- Discovered that each element has a unique atomic number
- Arranged elements by increasing atomic number
- Now all the elements fit into place based on properties

Episode 401

Modern Periodic Law

- Properties of elements repeat when elements are arranged by increasing atomic number
- Periodic function or repeats

Episode 401

Questions about the extended periodic table:

- Why do you think these elements get pulled out?
- It makes the periodic table more compact.

- Which element is in a different column than we are used to?
- He

- What happens to the number of energy levels as you begin each new row?
- Increases by 1

- What is the similar characteristic in each column?
- Electron distribution

Episode 401

Elements in the same column:

- Have similar electron distributions
- Have same number of valence electrons
- Electrons lost, gained, or shared
- Found in the s and p orbital of highest energy level

- Have similar chemical properties
- Ne:
- 1s2 2s2 2p6

- Kr:
- 1s2 2s2 2p6 3s2 4s2 3d10 4p6

- Ne:

Episode 401

Noble Gases

- Have full outer energy level
- Have 8 valence electrons
- Are stable
- (inert or unreactive)

Episode 401

Noble Gas Configuration

- Shorter way to do electron configurations using noble gases
- Find noble gas on the end of row before the element and put its symbol in brackets.
- Use diagonal rule to write the electron distribution for Sn (atomic # 50)
- 1s2 2s2 2p6 3s2 3p6 4s2 3d10 4p6 5s2 4d10 5p2

- Use the noble gas distribution to write electron distribution for Sn
- [Kr] 5s2 4d10 5p2

Episode 401

Noble Gas Configuration

- Find noble gas on the end of row before the element and put its symbol in brackets.
- Use diagonal rule to write the electron distribution for Fe (atomic # 26)
- 1s2 2s2 2p6 3s2 3p6 4s2 3d6

- Use the noble gas distribution to write electron distribution for Fe
- [Ar] 4s2 3d6

Episode 401

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