Download Electrons in the Atom

Electrons in the Atom
What do we know about electrons?
1. What is the basic information about electrons (charge,
mass, location)?
2. Explain the Bohr model structure. Draw a model for
carbon. Label the valence electrons. Draw a Lewis dot
structure for carbon.
3. What is the energy released when a hydrogen electron
moves from n=6 to n=2?
4. What is the difference between ground state and excited
state? How do electrons move between these two states?
5. What does it mean for an atom to become an ion? How
does the charge relate to the change in electrons?
Quantum Mechanics
• Using a mathematical description of the
wavelike behavior of particles on the atomic
level
• Electrons are located in orbitals (spaces where
they have a high probability of being found)
• Each orbital is described by three quantum
numbers
Atomic Orbitals
• Region of space in which there is a high
probability of finding an electron
• Principal quantum number, n
• Angular momentum quantum number l
• Magnetic quantum number ml
Principal Energy levels
• Quantum number, n
• Orbitals with the same value of n are in the
same shell
Energy level n
Max number
• n= 1, 2, 3, 4, etc.
electrons
1
2
2
8
3
18
4
32
Angular Momentum quantum number
l
• Orbitals with the same value of n and l are in the
same subshell
• Different shaped spaces within the sublevels
• s is spherical (1 orbital)
• p is dumbbell (3 orbitals)
• d varies (5 orbitals)
• f more complex (7 orbitals)
• (2 electrons per orbital)
Summary of Principal Energy Levels,
Sublevels, and Orbitals
Energy level n
Number of
sublevels
Type of sublevel
1
1
1s
2
2
2s, 2p
3
3
3s, 3p, 3d
4
4
4s, 4p, 4d, 4f
Magnetic quantum number ml
• Distinguishes orbitals of given n and l, of given
energy and shape but having different
orientation in space
• Values are integers from -1 to +1
Magnetic quantum number ms
• Refers to the two possible orientations of the
spin axis of an electron
• Values are +1/2 and -1/2
• Each orbital can contain two electrons with
opposite spins
• “Up”
• “Down”
• Spintronics
Keeping Track of Electrons
• All this information about electrons is very
hard to visualize and understand
• Electron configuration and orbital diagrams
can help
• Electron configuration: description of the
orbitals occupied by electrons
Three rules and electron configuration
•
•
•
•
Aufbau PrinciplePauli Exclusion Principal –
Hund’s Rule –
(Page 133-134)
Three rules and electron configuration
• Aufbau Principle- fill lowest energy level first
• Pauli Exclusion Principal – 2 electrons per
orbital with opposite spin
• Hund’s Rule – Bus Seat, electrons occupy
orbitals in the same energy level going in the
same spin direction
• (Page 133-134)
Energy Levels & Orbitals
Energy Levels
Sublevels
Orbitals
16
Aufbau diagram
Orbital diagram
Electron configuration
1s22s22p63s1
Sodium
• Electron Configuration Video
• Periodic Table Song