Electron Spin Quantum Number
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Diamagnetic: NOT attracted to a magnetic field field-- all electrons are paired Paramagnetic: substance is attracted to a magnetic field. Substance has unpaired electrons.. electrons
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3 Rules for Filling Electrons • Aufbau Principle – lowest energy to highest energy-regardless of numbers • Hund’s Rule – one electron goes in each orbital before two go in any • Pauli’s Exclusion Principle – no two electrons can have the same exact set of 4 quantum numbers – one goes up and the other goes down
Electron Configurations
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• After Aufbau came the most modern way of assigning electrons. • This way is done by using a number, letter and superscript number. • For example 3s2 • The first number is the same as “n” in quantum numbers. • The letter is the conversion of l, when 0,1,2,3 equals s, p, d, f • The last superscript number is the combination of ml and s.
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The Periodic Table is a Map • The periodic table is a map to the electron configurations. • It is arranged by the AUFBAU principle. • For example Let’s Write the Electron Configuration for Arsenic by Using only the table…
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Electron Filling Order
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Writing Atomic Electron Configurations Two ways of writing configs. One is called the spdf
notation.
spdf notation for H, atomic number = 1
1
1s
value of n
no. of electrons value of l
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Electron Configurations and the Periodic Table
Figure 8.7
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Configuration of Arsenic • Go from 1-33 • 1s22s22p63s23p64s23d104p3
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Writing Atomic Electron Configurations Two ways of writing configs. Other is called the orbital box notation.
ORBITAL BOX NOTATION for He, atomic number = 2
2
1s
1s
Arrows depict electron spin
One electron has n = 1, l = 0, ml = 0, ms = + 1/2 Other electron has n = 1, l = 0, ml = 0, ms = - 1/2
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Another Way of Showing electron Configuration is through the use of arrows. • The orbitals are shown as boxes (or blanks) • The electrons are shown as arrows (up or down is one electron) • When an orbital is complete, 2 opposite arrows are shown • One must go in each before 2 in any(equal sublevel) ,and a sublevel must be complete before you go to the next.
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Lithium Group 1A Atomic number = 3 1s22s1 ---> ---> 3 total electrons 3p 3s 2p 2s 1s
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Boron
3p
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Group 3A Atomic number = 5 1s2 2s2 2p1 ---> ---> 5 total electrons
3s 2p 2s 1s
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Carbon Group 4A Atomic number = 6 1s2 2s2 2p2 ---> ---> 6 total electrons 3p
Here we see for the first time HUND’S RULE. When placing electrons in a set of orbitals having the same energy, we place them singly as long as possible.
3s 2p 2s 1s
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Nitrogen
3p
Group 5A Atomic number = 7 1s2 2s2 2p3 ---> ---> 7 total electrons
3s 2p 2s 1s
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Neon Group 8A Atomic number = 10 1s2 2s2 2p6 ---> ---> 10 total electrons 3p 3s 2p 2s
Note that we have reached the end of the 2nd period, and the 2nd shell is full!
1s
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Aluminum Group 3A Atomic number = 13 1s2 2s2 2p6 3s2 3p1 [Ne] 3s2 3p1 3p
All Group 3A elements have [core] ns2 np1 configurations where n is the period number.
3s 2p 2s 1s
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Phosphorus Group 5A Atomic number = 15 1s2 2s2 2p6 3s2 3p3 [Ne] 3s2 3p3 All Group 5A elements have [core ] ns2 np3 configurations where n is the period number.
3p 3s 2p 2s 1s
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A Glitch? • • • • •
Write the noble gas configuration for 61Pm. [Xe] 6s2 5d1 4f4 Write the noble gas configuration for 74W. [Xe] 6s2 5d4 4f14 When the element ends in “d” add the one to the other “d” electrons • When the element ends in in “f” show the d1 electron.
Ion Configurations
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To form anions from elements add 1 or more ee- to subshell of highest n [or highest (n + l)]. P [Ne] 3s2 3p3 + 3e3e- -----> > 3 2 6 P [Ne] 3s 3p
Ion Configurations
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To form cations from elements remove 1 or more ee- from subshell of highest n [or highest (n + l)]. Al [Ne] 3s2 3p1 - 3e3e- -----> > Al3+ [Ne] 3p
3p 3s
3s
2p
2p 2s
2s
1s
1s
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Ion Configurations For transition metals, remove ns electrons and then (n - 1) electrons.
Fe [Ar] 4s2 3d6 loses 3 electrons ---> ---> Fe3+ [Ar] 3d5
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Ion Configurations For transition metals, remove ns electrons and then (n - 1) electrons.
Fe [Ar] 4s2 3d6 loses 2 electrons ---> ---> Fe+2 [Ar] 3d6 Fe2+
Fe 4s
3d
4s
3d
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Ion Configurations For transition metals, remove ns electrons and then (n - 1) electrons.
Fe [Ar] 4s2 3d6 loses 2 electrons ---> ---> Fe2+ [Ar] 3d6 Fe2+
Fe 4s
3d
4s
3d
Fe3+ 4s
3d
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What about excited electrons? • When an electron is excited, remember it jumps to a higher energy level. • Na 1s2 2s2 2p6 3s1 • Na* excited may look like this 1s2 2s2 2p5 3s2 • Add the electrons up to get the atomic number- look for jumping electrons!
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