orbital shape-orientationt (orbital structure of atom)
TRANSCRIPT
Chapter 5
Models of the
Atom
Bohr’s model…• Electrons are found in specific circular
paths (orbits) around the nucleus. • The electrons have fixed energies called
energy levels. (like rungs on a ladder)• The amount of energy required to move
an electron to another energy level is called a quantum.
The Quantum Mechanical model
• It is based on the energy and possible location of an electron.
• how likely it is to find an electron is described in terms of probability. (ie. Propeller blades)
• Based on work done by Shrodinger…
Atomic Orbitals
• The energy levels of electrons are labeled by principal quantum numbers (n)
• Each energy sublevel corresponds to an orbital of a different shape, which describes where the electron is likely to be found.
Atomic Orbitals
Shapes and Orientations of
Orbitals
1s Orbital
• Sphere around the nucleus
The one tells you that the electron is in the orbital closest to the nucleus
• S tells you about the shape
2s Orbital
• Similar to 1s except the electron is most likely in the region farther from the nucleus
p Orbitals
• At the first energy level there is only the 1s orbital, after the second energy level there are 2p orbitals
• Look like dumbbells • In the three directions
Remember….MAX NUMBER OF ELECTRONS
IN AN ENERGY LEVELENERGY LEVEL MAX # OF ELECTRONS
1 22 83 184 325 50
Electron Configuration
A detailed way of showing the order in which electrons fill in
around the nucleus
Electron Configuration Symbols1s 2
Energy Level Sub Level
(s, p, d, f )
# of e- in sub level
We must follow 3 rules…
• Aufbau priciple• Electrons occupy energy levels with lowest
energy first.
Pauli exclusion principle
• If 2 electrons occupy the same energy level they must have opposite spins.
Hund’s rule…
• Electrons that occupy orbitals of the same energy will have the maximum number of electrons with the same spin.
• 2p
To start we will use orbital filling diagrams to help us with electron
configurations….• ExampleBoron- has 5 electrons
Periodic table arrangement
• the quantum theory helps to explain the structure of the periodic table.
• n - 1 indicates that the d subshell in period 4 actually starts at 3 (4 - 1 = 3).
s (n) d (n - 1) p (n)1234567
f (n -2)
•Practice!!!
Summary: p orbitals and d orbitalsp orbitals look like a dumbell with 3 orientations: px, py, pz (“p sub z”). Four of the d orbitals resemble two dumbells in a
clover shape. The last d orbital resembles a p orbital with a donut wrapped around the middle.
1st Quantum #Principle Quantum #
(n)Specifies the energy level
that the electron is on.
2nd Quantum #Specifies the shape of the
sub level .
(l)
The 3rd (m) and 4th quantum numbers (s) …
• Deals with the orbital within the sublevel and the spin of the electron.
Four Energy Sub-LevelsEnergy Level Sub-level Type of sub # of
Orbitalss Sphere 2 1
p Dumbbell 6 3
d 4-Lobed 10 5
f 6-8 Lobed 14 7