Electron Configuration

Where do the electrons really hang out??

In those crazy orbitals!!

EC = The arrangement of electrons around a nucleus.

Let’s use the orbital shapes to place electrons.

Helium

Oxygen

Not sure about you…

I think that is a royal pain!

There is an easier way- Electron Configuration!

There are seven energy levels (we only worry about the

first 4).

Within the levels are subshells (s, p, d, f)

Each subshell can accommodate a certain number of orbitals

Each orbital can contain 2 electrons

Electron Configuration

3 Rules:Aufbau PrinciplePauli Exclusion PrincipleHund’s Rule

Molecular Orbital diagrams…

Helium

Oxygen

Aufbau Principle

Electrons enter the lowest energy level first

Different levels within a principal energy level can overlap the energy levels of an adjacent principal level

The filling of atomic orbitals does not follow a simple pattern.

Aufbau Principle- Here’s the pattern!!

1s

2s 2p

3s 3p 3d

4s 4p 4d 4f

5s 5p 5d 5f

Pauli Exclusion Principle

An atomic orbital may

describe at most 2 electrons 1 or 2 electrons may occupy

an orbital When an orbital contains

2 electrons, they must have

an opposite paired spin

Pauli Exclusion Principle Because of their magnetic

moments, we generally represent electrons using a single barbed arrow. The tip of the arrow points to the magnetic north of the electron

Hund’s Rule

When electrons occupy orbitals of equal energy (s, p, d, f), one electron enters each suborbital until all orbitals contain 1 electron with the same parallel spin

The second electrons then add to each orbital so that their spins are paired.

Heisenberg Uncertainty Principle

“The more precisely the position is determined, the less precisely the momentum is known in this instant, and vice versa.”

It is impossible to know the velocity and position of the electron at the same time.

Lets do the EC for using the rules! (Show MO and EC)

Fluorine

Sodium

Do WS Level 1 using MO diagrams

Some things to note

Valence electrons are those in the outer s and p orbitals.

Shared and unpaired electrons can be determined by looking at the outermost, incomplete orbital.

We can just use Aufbau– it is a little easier

1s

2s 2p

3s 3p 3d

4s 4p 4d 4f

5s 5p 5d 5f

Oxygen

Silicon

Calcium

Now try the Level 2 WS

Work on your Valence electron WS for 10 minutes!

Compare answers, discuss what you may be doing wrong.

Questions for me?

Warm Up

Can we tell which element by looking at the EC?

1s22s22p63s23p5

1s22s22p63s23p64s2 3d10

How did you do

Count the number of electrons

1s22s22p63s23p5 = 17 electrons, Chlorine

1s22s22p63s23p64s2 3d10= 30 electrons, Zinc

Did you write this in your notes?

Valence electrons are those in the outer s and p orbitals.

Shared and unpaired electrons can be determined by looking at the outermost, incomplete orbital.

Molecular Orbital Diagrams- Use lines to show orbitals

1s

2s 2p

3s 3p 3d

4s 4p 4d 4f

5s 5p 5d 5f

Li

Phosphorus

Vanadium

Go over some on the Valence electron WS

We can also use the periodic table to determine EC.

Try some more of the WS using the periodic table method…

Get out a half sheet of paper…

I will project the quiz as soon as the bell rings.

Be sure you write very neat!!

Noble Gas Configuration…

Write the noble gas in the period above the element… add the rest of the electron configuration.

Example:

Long form for Phosphorus: 1s22s22p63s23p3

Noble Gas Configuration for Phosphorus

Nobel gas above P = Ne

[Ne] 3s23p3

You need to be careful which periodic table you use for this!!

The Web-Elements PT works well…

Now you try!

Write the noble gas configuration for

V (atomic #23)

La (atomic #57)

Lr (atomic #103)

Now you try!

V (atomic #23)

La (atomic #57)

Lr (atomic #103)

Now you try!

Write the noble gas configuration for

V [Ar] 4s23d3

La [Kr]6s24f1

Lr [Xe] 7s24f146d1

Molybdenum (42)

1s22s22p63s23p64s23d104p65s14d5

Th (90)

[Rn] 7s25f2

Ground, Excited or Impossible?

Ground- If the electrons are in the orbitals that you would expect them to be in.

Excited- If some of the electrons are in a higher energy level.

Impossible- If the orbital doesn’t exist and/or the EC doesn’t make any sense.

Ground, Excited or Impossible?

Chlorine- 17 electrons

1s22s22p63s23p5

1s22s22p63s13p34s24p1

1s22s22p63s13p42d2

Ground, Excited or Impossible?

Zinc- 30 electrons

a. 1s22s22p63s23p64s23d86s2

b. 1s22s22p63s23p64s13d44p7

c. 1s22s22p63s23p64s2 3d10

You try…

Write the electron configuration for carbon…

Write an electron configuration for an excited atom.

Write an impossible EC…

Have your neighbor check your work.

Questions on the HW?

What happens with Ions??

Ions gain or lose electrons…

What is the electron configuration for the magnesium cation?

What about S2-

When removing electrons …

Remove the last electrons that were placed…

Unless there are electrons in the d orbital…then remove the last s electrons first.

Isoelectronic…

Different atoms that have the same electron configuration.

Na1+

Ne

F1-

Identify the atoms

An element that has a 2- charge that is isoelectronic with Neon.

Identify the atoms

An atom that has lost 3 electrons and is isoelectronic with He

Identify the atoms

An element that has a 2- charge that is isoelectronic with Neon.

An atom that has lost 3 electrons and is isoelectronic with He

An atom that has gained one electron and has the same EC as Cu.

Test