Orbitals and Electron Configurations

Orbitals and Electron Configurations

Where are the electrons?Where are the electrons?

The Rutherford AtomThe Rutherford Atom

Problems with the Rutherford Atom

Problems with the Rutherford Atom

Electrons should be attracted to the nucleus and repel each other

Couldn’t answer the question Why do the electrons stay in the electron

cloud? Why don’t the electrons collapse into the

massively positive nucleus?

Electrons should be attracted to the nucleus and repel each other

Couldn’t answer the question Why do the electrons stay in the electron

cloud? Why don’t the electrons collapse into the

massively positive nucleus?

The Bohr AtomThe Bohr Atom

Problems with the Bohr AtomProblems with the Bohr Atom

Fundamentally incorrect - only worked for the element Hydrogen

Couldn’t explain where the electrons were in atoms that had more than one electron

We don’t really know where an electron is at any one time, and we can’t predict it either

Fundamentally incorrect - only worked for the element Hydrogen

Couldn’t explain where the electrons were in atoms that had more than one electron

We don’t really know where an electron is at any one time, and we can’t predict it either

Things Bohr got rightThings Bohr got right

Energy Levels Ground State

Energy Levels Ground State

What we saw in the flame test labWhat we saw in the flame test lab

How we saw the light in the flame test lab

How we saw the light in the flame test lab

How we explain the light in terms of energy levels of the electrons in the atom

How we explain the light in terms of energy levels of the electrons in the atom

The difference between continuous and quantized energy

levels

The difference between continuous and quantized energy

levels

Albert Einstein’s contributionAlbert Einstein’s contribution

Developed quantum mechanics Showed that Isaac Newton’s theories for

motion do not give correct results when objects are traveling close to the speed of light

New equations in which the laws for motion are adjusted for the speed of light

Developed quantum mechanics Showed that Isaac Newton’s theories for

motion do not give correct results when objects are traveling close to the speed of light

New equations in which the laws for motion are adjusted for the speed of light

Max Planck’s contributionMax Planck’s contribution

German Physicist in the early 1900’s Said that Light is made up of discrete

bundles of energy called “quanta” (pleural of quantum)

Now known as “photon”

German Physicist in the early 1900’s Said that Light is made up of discrete

bundles of energy called “quanta” (pleural of quantum)

Now known as “photon”

Light has a Dual NatureLight has a Dual Nature

Behaves as both a particle (has properties of matter)

And a wave Has wave properties such as

Wavelength Frequency Speed (velocity)

Behaves as both a particle (has properties of matter)

And a wave Has wave properties such as

Wavelength Frequency Speed (velocity)

Photons of red and blue lightPhotons of red and blue light

Light as both a wave and a packet of energy

Light as both a wave and a packet of energy

Schrodinger and De BroglieSchrodinger and De Broglie

Mid-1920’s Louis Victor De Broglie from France Erwin Schrodinger from Austria Both young Physicists Suggested that if light can act like a wave

and a particle, then perhaps the same was true of the electron

Mid-1920’s Louis Victor De Broglie from France Erwin Schrodinger from Austria Both young Physicists Suggested that if light can act like a wave

and a particle, then perhaps the same was true of the electron

Wave-Mechanical ModelWave-Mechanical Model

Also called the quantum-mechanical model Electrons behave as both waves and

particles (like light) De Broglie and Schrodinger applied a

mathematical analysis to their idea and found that it worked for all atoms, not just hydrogen

Also called the quantum-mechanical model Electrons behave as both waves and

particles (like light) De Broglie and Schrodinger applied a

mathematical analysis to their idea and found that it worked for all atoms, not just hydrogen

Wave Mechanical ModelWave Mechanical Model

1. Electrons do not follow definite paths2. Electrons are in a diffuse cloud of negative

charge around the nucleus (like the Rutherford atom)

3. There are areas around the nucleus that correspond with certain energy levels (like the Bohr Model)

4. The areas around the nucleus where the electron probably is (energy levels) are called orbitals

1. Electrons do not follow definite paths2. Electrons are in a diffuse cloud of negative

charge around the nucleus (like the Rutherford atom)

3. There are areas around the nucleus that correspond with certain energy levels (like the Bohr Model)

4. The areas around the nucleus where the electron probably is (energy levels) are called orbitals

Firefly experimentFirefly experiment

Electron ProbabilityElectron Probability

The Hydrogen 1s OrbitalThe Hydrogen 1s Orbital

OrbitalsOrbitals

Do not have distinct boundaries (like earth’s atmosphere)

Boundary is mapped at 90% electron probability (by convention)

Electrons can be found outside of this boundary We can never map exactly where an electron is at

any given moment All elements have all of the orbitals

Do not have distinct boundaries (like earth’s atmosphere)

Boundary is mapped at 90% electron probability (by convention)

Electrons can be found outside of this boundary We can never map exactly where an electron is at

any given moment All elements have all of the orbitals

The first four principle energy levels

The first four principle energy levels

Sub-LevelsSub-Levels

As the Energy Level number increases, the further away from the nucleus the electron is, and the higher the energy level

The further away from the nucleus the energy level is, the more space there is to divide up

Each Energy level is divided further into sub-levels

As the Energy Level number increases, the further away from the nucleus the electron is, and the higher the energy level

The further away from the nucleus the energy level is, the more space there is to divide up

Each Energy level is divided further into sub-levels

How principle energy levels are divided into sub-levels (s,p,d,f)How principle energy levels are divided into sub-levels (s,p,d,f)

Second Principle Energy Level with sublevels corresponding to orbitalsSecond Principle Energy Level with sublevels corresponding to orbitals

1s and 2s orbitals (showing the relative size)

1s and 2s orbitals (showing the relative size)

The 2p orbitals (three of them)The 2p orbitals (three of them)

Diagram of Principle Energy Levels 1 and 2

Diagram of Principle Energy Levels 1 and 2

Relative size of the 1s, 2s, 3s orbitals

Relative size of the 1s, 2s, 3s orbitals

The 3d orbitalsThe 3d orbitals

Electron FillingElectron Filling

Aufbau Principle - electrons prefer the space closest to the nucleus

Therefore all of the electrons are arranged around the nucleus from lowest energy level to highest energy level

The most attractive orbital to any electron is the 1s orbital, then 2s, 2p, 3s, 3p, 4s, 3d, and so on

This corresponds to Bohr’s idea of the ground state

Aufbau Principle - electrons prefer the space closest to the nucleus

Therefore all of the electrons are arranged around the nucleus from lowest energy level to highest energy level

The most attractive orbital to any electron is the 1s orbital, then 2s, 2p, 3s, 3p, 4s, 3d, and so on

This corresponds to Bohr’s idea of the ground state

Electron fillingElectron filling

Pauli Exclusion Principle - orbitals can hold a maximum of two electrons

Electrons repel each other and don’t want to share the same space (same negative charge)

Electrons will share the same space if they are spinning in opposite directions (like a magnet)

Pauli Exclusion Principle - orbitals can hold a maximum of two electrons

Electrons repel each other and don’t want to share the same space (same negative charge)

Electrons will share the same space if they are spinning in opposite directions (like a magnet)