Dmitri Mendeleev

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# Dmitri Mendeleev - PowerPoint PPT Presentation

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

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Presentation Transcript
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

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