orbital notation, noble gas notation, and valence electrons
Post on 24-Dec-2015
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Noble Gases
Method of representing electron configurations of noble gasesElements in the last column of the periodic
tableHave 8 electrons in their outermost orbitalExtremely stable
Nobel Gas Notation Recall, the electron configuration for Na is:
Na: 1s2 2s2 2p6 3s1
We can abbreviate the electron configuration by indicating the innermost electrons with the symbol of the preceding noble gas.
The preceding noble gas with an atomic number less than sodium is neon, Ne. We rewrite the electron configuration:
Na: [Ne] 3s1
Orbital Notation In electron configurations, we wrote the orbitals together
as one sublevel Example:
2px 2py 2pz all became the 2p sublevel
We do not get to see how the individual electrons line up
In orbital notations, each sublevel is written to show the electron’s spins in each direction
Orbital notation shows you where each specific electron is placed (in order) and what it’s “spin” is.
Electron Configuration for Na Na, 11e-
1s2 2s2 2p6 3s1
We are now going to represent each electron as a “half arrow”
We must fill in the electrons as we did previously but show them using arrows on the orbital notation diagram
The first electron in an orbital is placed up (+1/2 spin)
Exceptions to Predicted Configurations Chromium
Incorrect: [Ar] 4s23d4
Correct: [Ar] 4s13d5
Copper:Incorrect: [Ar] 4s23d9
Correct: [Ar] 4s13d10
Elements in group 6 (s1d5) and group 11 (s1d10) have greater stability with half-filled and filled sets of s and d orbitals
Valence Electrons Only certain electrons determine the chemical
properties of an element
Valence Electrons:Electrons in the atom’s outermost orbitals – generally
those orbitals associated with the atom’s highest principal energy level orbitals (s and p)
Example:Sulfur contains 16 electrons6 electrons occupy the outermost 3s and 3p orbitalsTherefore, Sulfur has 6 valence electrons
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