Download Quantum Numbers and Electronic Configuration

Quantum Numbers
• Quantum Numbers specify the properties of atomic
orbitals and their electrons
• There are four quantum numbers:
• principal quantum number
• orbital quantum number
• magnetic quantum number
• spin quantum number
Principal Quantum Number
• The principal quantum number (n) specifies the main energy
levels around the nucleus
• As n increases, the distance from the nucleus increases (So as the
numbers become larger the levels become further from the
nucleus)
• Currently the values for n are 1 to 7
• These orbitals are called subshells or sublevels
• The four most common Principal quantum numbers are given
letter abbreviations
s, p, d, f
Orbital Quantum Number
•Orbital Quantum Number ( l ) indicates
the shape of the orbital where the
electron can be found
“s” Orbital
“p” Orbital
“d” Orbital
“f” Orbital
Magnetic Quantum Number
• 3. Magnetic Quantum Number (ml ): indicates the
orientation of an orbital about the nucleus
• it tells which axis that sublevel is located on (x, y, or z
axis)
Spin Quantum Number
•The Spin Quantum Number (s) is a value (of
1/2) that describes the angular momentum
of an electron. An electron spins around an
axis and has both angular momentum and
orbital angular momentum. Because
angular momentum is a vector, the Spin
Quantum Number (s) has both a magnitude
(1/2) and direction (+ or -)
Using Quantum Numbers
•Quantum numbers can be used to write electron
configurations
•Electron configurations show how electrons are
most likely distributed around the nucleus
Rules for Electron Configurations
•1. Aufbau Principle: Electrons enter orbitals of lowest
energy first
•2. Hund’s Rule: Orbitals of equal energy are each
occupied by one electron before any one orbital is
occupied by a second electron
Rules for Electron Configurations
• 3. Pauli Exclusion Principle: an atomic orbital may describe
at most two electrons
• The maximum number of electrons in any orbital is “2”
• No two electrons in the same atom can have the same set of
four quantum numbers
Guidelines for Electron Configurations
1. Determine number of electrons
2. Each orbital can hold 2 electrons
3.
A “ s ” sublevel has 1 orbital and holds 2 electrons
A “ p ” sublevel has 3 orbitals and holds 6 electrons
A “ d ” sublevel has 5 orbitals and holds 10 electrons
A “ f ” sublevel has 7 orbitals and holds 14 electrons
Order of Filling of Energy Levels
• 1s
• 2s
• 3s
• 4s
• 5s
• 6s
• 7s
2p
3p
4p
5p
6p
7p
3d
4d
5d
6d
7d
4f
5f
6f
7f
Warm-Up
•The density of a substance is 5.25 g/mL.
What is the mass(in kilograms) of 0.75 L of
the substance?
Warm-Up
• What elements are the following:
• 1s22s22p4
1s22s22p63s23p64s23d7
1s22s22p63s23p64s23d104p65s24d105p11
Practice Long Hand Electron Configurations
• Cd
•B
•P
• Ba
• As
•I
• Na
Review
•Write the Long Hand/Expanded electron
configuration for the following elements:
•Sn
•Ga
•Y
Noble Gas Electron Configuration
•Place the following Element using the Noble Gas/short
hand electron configuration:
•Sc
•I
•Ru
•Fr
•Fe
•F
Practice Problems
•Write the Noble Gas Electron Configuration
for the following:
•Tc
•Zn
•K
•I
•P
Orbital Diagrams
•Orbital diagrams show how electrons fill each
sublevel
•s has 1 sublevel
•p has 3 sublevels
•d has 5 sublevels
•f has 7 sublevels