Chapter 5

So far…..What are the components of an atom?

What is in the nucleus?What are the charges of the subatomic particles?

Where are the electrons?

Rutherford model • Planets around the sun• Could only explain simple properties of atoms• Red fire vs blue fire

Bohr model• Each electron is on an

orbit that has a fixed energy.• These orbits are called

energy levels.• Orbit = energy level• No “in between” levels

(ladder example)• A quantum is the

amount of energy needed to move from one level to the next.

Electron Cloud Modelaka Quantum Mechanical Model

There is no specific path electrons take

Demonstrates the probability of finding an electron in that location.

No more orbits. We now have energy levels.

Atomic Orbitals (aka sublevels)A region of space where there is a high probability of finding an e- (~90%)

Each energy level has orbitals. These are not orbits. Bad choice of name.

Atomic Orbitals

Each atom is categorized by the number of levels and sublevels.

The number of levels are referred to as n.Also, the number of sublevels equals n.So….

energy level 1 has 1 sublevel,energy level 2 has 2 sublevels, etc…..

Atomic OrbitalsThere are 4 types or orbitals and we will only focus on 3 (s orbitals, p orbitals, and d orbitals)

The number of sublevels = n2 where n=the energy level

Each orbital has a different shape and they all build on one another.

Each orbital can only hold 2 e- so the number of electrons at each energy level = 2 n2 .

Summary of energy levels…..Energy level (n)

# of sublevels (n)

Sublevels (n2) # of e- that n can hold (2n2)

1 1 1 (1 s orbital) 2

2 2 4 (1 s orbital and 3 p orbitals) 8

3 3 9 (1 s orbital, 3 p orbitals, and 5 d orbitals)

18

4 4 16 (1 s orbital, 3 p orbitals, and 5 d orbitals, and 7 f orbitals).

32

S orbitals Sphere shaped

Hold 2e-

Cross section

P orbitalsDumbbell shapedHold 2e- each for a total of 6

This is 1 p orbital, not 2

S and P orbitals together

D orbitals

Hold 2e- each for a total of 10.

Summary of orbitals.

Summary of energy levels…..Energy level (n)

# of sublevels (n)

Sublevels (n2) # of e- that n can hold (2n2)

1 1 1 (1 s orbital) 2

2 2 4 (1 s orbital and 3 p orbitals) 8

3 3 9 (1 s orbital, 3 p orbitals, and 5 d orbitals)

18

4 4 16 (1 s orbital, 3 p orbitals, and 5 d orbitals, and 7 f orbitals).

32

Electron Configurations

Rule #1 – electrons occupy lowest energy level first. S sublevel is always the

lowest…….ALWAYS

Electron Configurations Rule # 2 – an

orbital may only hold 2 electrons with opposite spins.

Electron configurations Rule #2 - Every orbital in

a sublevel is singly occupied before any orbital is doubly occupied

Conceptual Problem 5.1 Write the electron

configuration for a phosphorus atom. First, how many electrons need

“homes?” Next, place electrons in the

orbital with the lowest energy level.

Continue adding electrons in orbitals with the next higher energy.

1s2 2s2 2p6 3s2 3p3

____ ____ ____ ____ ____ _____ ____ _____ ____

1s 2s 2p 2p 2p 3s 3p 3p 3p

Atomic Spectra

Atomic Spectra

Ground stateLowest possible energy

Excited stateAbsorption of energy by electronElectron moves to the next energy level. Light is emitted when it moves back to it’s ground state.

This transition from the excited back to ground state produces both a distinctive visible color and emission spectrum. “Spectral fingerprints.”

Atomic Spectra

Atomic Spectra

Atomic Spectra

Atomic spectra

Atomic Spectra

Lab

H

He

Ne

Na

Hg

C

N

Mg

Atomic spectra

Atomic spectra

Atomic spectra

Wavelength – distance between crests

Atomic spectra

Frequency – number of wave cycles in a given time

Atomic spectra

Amplitude – height of wave from zero to crest

Atomic spectra

The atomic orbitals – move to end https://www.youtube.com/watch?v=9E3QaRxqXZc

https://www.youtube.com/watch?v=zBgbhasbI2E&feature=iv&src_vid=Ewf7RlVNBSA&annotation_id=annotation_278233