Electron Configuration Chapter 3 Section 3.2 Things we know… Electrons are negatively charged....
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Transcript of Electron Configuration Chapter 3 Section 3.2 Things we know… Electrons are negatively charged....
Electron Configuration
Chapter 3 Section 3.2
Things we know… Electrons are negatively charged. Electrons are very small
1/2000 that of a proton or neutron 9.108 X 10-28 grams
Electrons determine the chemical behavior of the atom.
According to Modern Atomic Theory: Electrons travel around the nucleus
billions of times per second. Not in perfect orbits like seen here
in the Bohr Model, but rather in complex patterns in a
space called the “electron cloud.”
The exact location of an electron is never known!!
n = energy level
How many energy levels does Li have?
How many energy levels does Sr have?
Determining Energy Level
Energy Levels = Periods A row on the periodic
table is called a period.
What period is Ca in? Al is in the third
period, how many energy levels does it have? Overhead notes here
Energy levels can hold a certain number of electrons
2
8
8
Energy levels have sublevels called “orbitals.”
S Orbitals
P Orbitals
We will work with two types:
S Orbitals can hold 2 electrons
P Orbitals can hold 6 electrons
Add up electrons orbitals hold and you know how many electrons the level can hold.
2
8
8
Larger energy levels have more orbitals.
Besides “s” and “p” orbitals, there are also “d” and “f” orbitals.
Orbitals have different unusual shapes.
S Orbitals are sphere-shaped.
P Orbitals are dumbbell-shaped.
d & f Orbitals have wild shapes.
A Copper atom simulation!
Energy levels have sublevels called orbitals
Energy levels have 1 to 4 different orbitals.
The orbitals are called S P D F
The periodic table reflects the arrangement.
What are Orbitals? The places electrons
probably are- They look like
Spheres Dumbbells Donut things…Ab
roller
Energy Levels have 1 – 4 orbitals Period 1 has 1
orbital, what is it? Period 2 has 2
orbitals, what are they?
How many orbitals does period 3 have?
A. General Rules Pauli Exclusion Principle
Each orbital can hold TWO electrons with
opposite spins. We note this with two arrows
going in the opposite directions. You can use
any symbol you choose but use something.
A. General Rules Aufbau Principle
Electrons fill the lowest energy orbitals first.
“Lazy Tenant Rule” You see the ground floor is easy but climbing the stairs is hard work!
Ground Floor
RIGHTWRONG
A. General Rules Hund’s Rule
Within a sublevel, place one e- per orbital before pairing them.
“Empty Bus Seat Rule”
O 8e-
Orbital Diagram
Electron Configuration
1s2 2s2 2p4
B. Notation
1s 2s 2p
Shorthand Configuration
S 16e-
Valence Electrons
Core Electrons
S 16e- [Ne] 3s2 3p4
1s2 2s2 2p6 3s2 3p4
B. Notation Longhand Configuration
s-block
1st Period
1s1 1st column of s-block
C. Periodic Patterns Example - Hydrogen
1
2
3
4
5
6
7
C. Periodic Patterns Shorthand Configuration
Core e-: Go up one row and over to the Noble Gas.
Valence e-: On the next row, fill in the # of e- in each sublevel.
Writing electron configuration S-orbitals always fill
first. Each s-orbital can
hold 2 electrons.
Lets Try Another! P orbitals can hold up
to 6 electrons P orbitals only fill
when the s orbital before it has filled
Nitrogen has 7 electrons
1s2 2s2 2p3
Writing Electron Configuration Nitrogen has seven
electrons 1s2 2s2 2p3
Neon has ten electrons
How would Ne be written?
1s2 2s2 2p6
Why do we need this stuff??? To determine the valance electrons
Electrons in the outermost energy level Valance electrons help determine the
chemical activity of the element.(Its attitude) How many valance electrons does carbon have?
1s2 2s2 2p2
How many valance electrons does Beryllium have?
1s2 2s2
Those Crazy Electrons!