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 ID: 140901
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Slide1
Dmitri Mendeleev
Arranged elements by increasing atomic massPredicted properties of missing elements
Episode 401Slide2
Henry Moseley
Discovered that each element has a unique atomic numberArranged elements by increasing atomic numberNow all the elements fit into place based on properties
Episode
401Slide3
Modern Periodic Law
Properties of elements repeat when elements are arranged by increasing atomic numberPeriodic function or repeats
Episode
401Slide4
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?HeWhat happens to the number of energy levels as you begin each new row?
Increases by 1What is the similar characteristic in each column?Electron distribution
Episode
401Slide5
Elements in the same column:
Have similar electron distributionsHave same number of valence electronsElectrons lost, gained, or sharedFound in the s and p orbital of highest energy level
Have similar chemical propertiesNe: 1s
2 2s
2
2p
6
Kr:
1s
2
2s
2
2p
6
3s
2
4s
2 3d10 4p6
Episode
401Slide6
Noble Gases
Have full outer energy level
Have 8 valence electronsAre
stable (inert or
unreactive
)
Episode
401Slide7
Using the periodic table to find electron distributions:
Episode 401Slide8
Noble Gas Configuration
Shorter way to do electron configurations using noble gasesFind 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)1s
2 2s2 2p
6 3s2
3p
6
4s
2
3d
10
4p
6
5s
2
4d
10
5p
2Use the noble gas distribution to write electron distribution for Sn[Kr] 5s
2
4d
10
5p
2
Episode
401Slide9
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
4s
2
3d
6
Use the noble gas distribution to write electron distribution for Fe
[
Ar
] 4s
2
3d
6
Episode
401