1. Electrons in Atoms: Electron Configuration
Chemistry
EQs: What is the relationship between matter and energy?
How does the behavior of electrons affect the chemistry of atoms?

2. SC3 Students will use the modern atomic theory to explain the characteristics of atoms. b. Use the orbital configuration of neutral atoms to explain its effect on the atom’s chemical properties. f. Relate light emission and the movement of electrons to element identification.
GPS

3. Vocabulary Aufbau Principle Pauli Exclusion Principle Hund’s Rule
Electron Configuration
Valance Electron
Energy levels
Lewis Structure
Ground state
Excited state
Orbitals
Quantum
Vocabulary

5. Excited Electrons

6. Bohr’s Model: electrons orbit the nucleus; only orbits in certain energies are permitted.
Ground State- lowest E level
Excited State- Higher than ground state.
The e- are raised to the next level, then release light when they return to ground state
Must have enough E to raise to next level or won’t happen.
Niels Bohr, a young Danish physicist working in Rutherford’s lab, proposed a quantum model for the hydrogen atom that correctly predicted the frequencies of the lines in hydrogen’s AES.
*Bohr’s model demonstrated that a hydrogen atom has certain Energy states that are allowed; where the orbits represent the energy levels.
An atom with excess energy is said to be in an excited state.
The lowest possible energy state of an atom is called its ground state.
Bohr Model of the Atom:

7. Bohr Model

8. Bohr Model of the atom

9. DeBroglie-
Quantum Mechanics- light behaves as wave & particles
Visible objects (baseball) have  too small to see, need very small object to detect 
 Heisenburg Uncertainty Principle- Can’t know the position & speed of electron at the same time
Electrons

10. Bohr Model  Quantum Model
E- do not fall towards nucleus
E- reside in electron clouds called orbitals

11. Energy levels- region around nucleus where e- likely to be found (electron density is high)
Quantum- amount of energy for e- to jump levels
Continuous- ramp, no units
Quantitized- fixed levels, fixed units
Electrons

12. Schrodinger- estimates the probability of e- to be in certain area; electrons are like a fuzzy cloud, but more dense= more likely to find e- 90% of the time in a particular location
Orbitals-Wave functions with corresponding densities (shape and energy)
**orbital is NOT the same as Bohr’s orbit

13. Electron configuration
Row=Period=Energy Level => horizontal
Column= Group/ Family=> vertical
Elements in the same family have the same # of valence electrons & share similar chemical properties.
Valence electrons= e- in to last energy level.
Valence e- correspond w/ group # (does not include transition elements):
Group 1A= 1 valence e-
Group 2A= 2 valence e-
Group 3A (13) = 3 valence e-
Group 4A (14) = 4 valence e-
Group 5A (15) = 5 valence e-
Group 6A (16) = 6 valence e-
Group 7A (17) = 7 valence e-
Group 8A (18) = 8 valence e-  FULL SET; STABLE

14. Electron Configuration
Tells the arrangement of electrons around the nucleus of an atom
Written in ground state, which is the lowest energy & most stable arrangement
e- arrange from lowest to highest E level

15. Electron configuration .
Orbital: the 3-D space around the nucleus that describes an electrons probable location.
Energy Level (n): indicate the relative sizes & energies of atomic orbitals.
As n increases, the orbitals become larger, and the e- spends more time farther from the nucleus.
n = major energy levels; n = 1-7; correspond w/ the 7 rows on the P.T.
Sublevel: energy levels contained w/in a energy level;
s, p, d, f
Electron configuration .

16. Electron Configuration

17. What shape are the orbitals?
s and p Orbitals
What shape are the orbitals?

18. Electron Configuration
Tells the arrangement of electrons around the nucleus of an atom
Written in ground state, which is the lowest energy & most stable arrangement
Follows 3 rules:
Aufbau Principle
Pauli Exclusion Principle
Hund’s Rule

19. Each electron will occupy the lowest available energy level 1st, then higher energy levels.
Aufbau Principle

20. Pauli Exclusion Principle
A maximum of 2 electrons with opposite spins
can fit in an orbital (No more than 2 e- can occupy orbitals).
e- in the same orbital must have opposite spin (repulsion);
Show each orbital w/ its own box
One is spinning clockwise & the other is counter clockwise, Show this with one arrow going up & one pointing down.
NOT 
 

21. Hund’s Rule
Single electrons with the same spin must occupy each equal energy level before additional electrons with opposite spins can be added
e- enter orbitals singularly, then pair up
Example: when filling the p sublevel with 4e-, each box gets 1 before doubling up one box
NOT   

22. Electron Configuration-
Using the PT:
The principal quantum number , n = period.
There are 4 blocks: (s, p, d, f)
Noble gases:full s & p level making them inert (stable).
Alkali Metals- s1
Alkaline Earth Metals- s2
Transition Elements- d1-d10
Inner Transition Elements- f1-f14
Electron Configuration-

23. Electron Fill Sequence

24. Electron Configuration

25. Electron Sequence Model
Follow the yellow brick road 1s 2s 3s 4s 5s 6s 7p 6p 5p 4p 3p 2p 6d 5d 4d 3d 4f 5f 7s
Electron Sequence Model

26. Electron Configuration
Examples:
F 1s22s22p5
Cl 1s22s22p63s23p5
Al 1s22s22p63s23p1
Br 1s22s22p63s23p64s23d104p5
Electron Configuration

27. Orbital Diagrams” Uses boxes to represent orbitals  1s 2s 2p 3s 3p 4s 3d 4p   1s 2s 2p 3s 3p 4s 3d 4p   1s 2s 2p 3s 3p 4s 3d 4p   1s 2s 2p 3s 3p 4s 3d 4p
Orbital Diagrams” Uses boxes to represent orbitals

28. Noble Gas Notation Simplified version of writing e- configurations
Noble gas is placed in brackets [ ]

29. When doing configurations for large numbers of electrons, we can take a short cut using noble gases. (yay!)
Example, lets try Sulfur: (16 electrons)
The noble gas that comes before Sulfur is: Neon
Noble gas is placed in brackets [ ]
Place noble gas in bracket to represent the e- configuration up to that noble gas.
Write the rest of the e- config. for that element.
So we could shortcut by writing: [Ne] 3s2 3p4
Now you try: Manganese and Strontium
Noble Gas Shortcut

30. Electron Configuration and Orbital Notation

31. e- in the outer most energy level that determines chemical properties
Lithium = 1s2 2s1
Bromine = 1s2 2s2 2p6 3s2 3p6 4s2 3d10 4p5
Aluminum = [Ne] 3s2 3p1
Family Number
VE are the electrons
available to form chemical
bonds w/ other elements.
Valence Electrons

32. Lewis Dot Structure: Electron Dot
Chemical symbol & valence electrons of atom
Valuable in showing how atoms share electrons in covalent bonds
We can draw Lewis structures for every element using valence electrons
Count the # of valence electron, then arrange then around the symbol for the atom one at a time; up to 8 electrons.
Arrange 1/ side around the symbol, then couple up if more than 4 electrons.

33. Lewis Dot