Electron configuration Electrons in Atoms Electron configuration

http://www.youtube.com/watch?v=Vb6kAxwSWgU

Electrons The arrangement of electrons in an atom will determine the chemical and physical properties of that atom (or ion). Because of this it is important to know where those electrons are (or are most likely to be found)

Where do we find electrons? Electrons in atoms are arranged as LEVELS (n) SUBLEVELS (l) ORBITALS (ml) Think of these as the electrons address.

Energy Level (n) This tells you how far the electron is from the nucleus, the higher the energy level the further from the nucleus Currently n can be 1 thru 7, because there are 7 periods on the periodic table

Energy Levels n = 1 n = 2 n = 3 n = 4

Sublevels attempt to describe where the electrons are likely to be found s, p, d, f ORBITALS Found within the sublevels Each orbital can hold a maximum of 2 electrons

Types of Orbitals The most probable area to find these electrons takes on a shape So far, we have 4 shapes. They are named s, p, d, and f. Each orbital has different “flavors” s= 1 flavor p = 3 flavors d = 5 flavors f = 7 flavors Each “flavor” can hold a maximum of 2 electrons

How many electrons can be in a sublevel? Remember: A maximum of two electrons can be placed in an orbital. s orbitals p orbitals d orbitals f orbitals Number of orbitals 1 3 5 7 Number of electrons 2 6 10 14

Electron possible per energy level 2n2 = the number of electrons possible in an energy level Ex: 3rd energy level, n=3 2(3)2 = 18

2p4 Electron Configurations Number of electrons in the sublevel Energy Level Sublevel 1s2 2s2 2p6 3s2 3p6 4s2 3d10 4p6 5s2 4d10 5p6 6s2 4f14… etc.

Pauli Exclusion Principle General Rules Pauli Exclusion Principle Each orbital can hold TWO electrons with opposite spins.

General Rules Aufbau Principle Electrons fill the lowest energy orbitals first. “Lazy Tenant Rule”

Diagonal Rule 1 2 3 4 5 6 7 s s 2p s 3p 3d s 4p 4d 4f s 5p 5d 5f 5g? Steps: Write the energy levels top to bottom. Write the orbitals in s, p, d, f order. Write the same number of orbitals as the energy level. Draw diagonal lines from the top right to the bottom left. To get the correct order, follow the arrows! 1 2 3 4 5 6 7 s s 2p s 3p 3d s 4p 4d 4f By this point, we are past the current periodic table so we can stop. s 5p 5d 5f 5g? s 6p 6d 6f 6g? 6h? s 7p 7d 7f 7g? 7h? 7i?

General Rules Hund’s Rule WRONG RIGHT Within a sublevel, place one e- per orbital before pairing them. “Empty Bus Seat Rule” WRONG RIGHT

1s2 2s2 2p4 O Notation 1s 2s 2p 8e- Orbital Diagram Electron Configuration 1s2 2s2 2p4

S 16e- 1s2 2s2 2p6 3s2 3p4 Notation Core Electrons Valence Electrons Longhand Configuration S 16e- 1s2 2s2 2p6 3s2 3p4 Core Electrons Valence Electrons

S 16e- [Ne] 3s2 3p4 Notation Noble Gas Valence Electrons Shorthand Configuration S 16e- [Ne] 3s2 3p4 Noble Gas Valence Electrons

Lithium Group 1A Atomic number = 3 1s22s1 ---> 3 total electrons

Carbon Group 4A Atomic number = 6 1s2 2s2 2p2 ---> 6 total electrons

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