electromagnetic radiation

• a form of energy that exhibits wave-like behavior as it travels through space.

Visible light

• Type of electromagnetic wave• The only type of electromagnetic wave that

we can see = visible light

The atom and visible light

• In the early 1900s, scientists observed certain elements emitted visible light when heated in a flame.

• Analysis of the emitted light revealed that an element’s chemical behavior is related to the arrangement of the electrons in its atoms.

Light Moves in Waves

• Visible light is a type of electromagnetic radiation, a form of energy that exhibits wave-like behavior as it travels through space.

• All waves can be described by several characteristics.

Characteristics

• The wavelength (λ) is the shortest distance between equivalent points on a continuous wave.

• The frequency (ν) is the number of waves that pass a given point per second.

• The amplitude is the wave’s height from the origin to a crest.

The speed of light (3.00 X 108 m/s) is the product of it’s wavelength

and frequency c = λν.

What is the frequency of light that has a wavelength of 550 nm? (1m

= 1 x 109 nm)?

What is the wavelength of light, in cm, that has a frequency of 9.60 x

1014 Hz (1/s)?

What is the frequency of light (Hz) that has a wavelength of 740 nm

(1m = 1 X 109 nm)?

• The wave model of light cannot explain all of light’s characteristics.

• Matter can gain or lose energy only in small, specific amounts called quanta.

• A quantum is the minimum amount of energy that can be gained or lost by an atom.

• Albert Einstein proposed in 1905 that light has a dual nature.

• A beam of light has wavelike and particlelike properties.

• A photon is a particle of electromagnetic radiation with no mass that carries a quantum of energy.

• Sunlight splits into a spectrum of colors when it passes through a prism.

• Colors of the spectrum include red, orange, yellow, green, blue, indigo and violet.

• Red light has the longest wavelength and the lowest frequency, while violet light has the shortest wavelength and the highest frequency.

Dispersion of white light by a prism

• Every element emits light after it absorbs energy. The light that is emitted (atomic emission spectra) is different for every element, and differs from white light because it is not continuous.

• The atomic emission spectrum of an element is the set of frequencies of the electromagnetic waves emitted by the atoms of the element.

Each element’s atomic emission spectrum is unique.

• Planck showed that the amount of radiant energy (E) absorbed or emitted by a substance is proportional to the frequency of the radiation.

Dispersion of white light by a prism

A photon of red light carries less energy than a photon of blue light

• Ephoton = h Ephoton represents energy.h is Planck's constant. represents frequency

Planck’s constant has a value of 6.626 X10–34 J ● s.

What is the energy of a photon with a frequency of 2.94 x 1015 cycles per second (s-1 or Hz)?

What is the energy of a light particle with a wavelength of 675

nm?

Bohr’s model

The Quantum Mechanical Model of an atom

• Louis de Broglie (1892–1987) hypothesized that particles, including electrons, could also have wavelike behaviors.

• Heisenberg showed it is impossible to take any measurement of an object without disturbing it.

• The Heisenberg uncertainty principle states that it is fundamentally impossible to know precisely both the velocity and position of a particle at the same time.

• The only quantity that can be known is the probability for an electron to occupy a certain region around the nucleus.

What does this all mean?

• Electrons do not move in circular paths around the nucleus of an atom

• It is impossible to determine the exact location of an electron at any given time

• We can only calculate the probability that an electron will occupy a region around the nucleus

Energy Levels

• Electrons can exist in energy levels 1-7• The higher the energy level, the further from

nucleus• Energy level 1 is closer to the nucleus of an

atom than energy level 2

Energy levels

• The maximum number of electrons that can occupy an energy level is given by the formula 2n2, where n is the # of the energy level.

• 1st energy level up to 2 electrons• 2nd energy level up to 8 electrons• 3rd energy level up to 18 electrons• 4th energy level up to 32 electrons

Energy levels can be divided into sublevels

• Each energy level can be divided into sub levels (s, p, d, f)

• Each sublevel contains orbitals• Each orbital can contain a maximum of 2

electrons

Energy sublevel

• Max of 2 electrons per orbital• “s” sublevel – 1 orbital per sublevel (up to 2

total electrons)• “p” sublevel – 3 orbitals per sublevel (up to 6

total electrons• “d” sublevel – 5 orbitals per sublevel (up to 10

total electrons)• “f” sublevel – 7 orbitals per sublevel (up to 14

total electrons)

Sum it up

• Electrons surround the nucleus in electron clouds• Electrons can exist in different energy levels (1-7)• Each energy level contains sublevels. Possible

sublevels for each energy level (s,p,d,f)• Each sublevel has orbitals. • S= 1 orbital p= 3 orbitals d= 5 orbitals• f= 7 orbitals

• Electron configuration – the way in which electrons are arranged in energy levels outside of the nucleus.

• Orbital notation – a way of showing the electron configuration using arrows to represent each electrons and boxes to represent each orbital.

1. Aufbau principle – electrons enter orbitals of lowest energy first.

2. Pauli exclusion principle – an atomic orbital may hold at most two electrons.

Electrons within the same orbital have opposite spins.

3. Hund’s rule – one electron must be put in each orbital of a sublevel before any one orbital can have two electrons in it.

Electron Configurations

• You may be saying, seriously I have to memorize all of that! YUK!

• Don’t give up, it’s not that hard!• I promise I have good news!• Great news!! If you can read, you can predict

the location of the electrons in an atom without memorizing anything except the letters s, p, d, f

• Can you read and memorize s,p,d,f?

Electron Configurations

• Oh, wait…. I forgot you have to be able to master one more skill. This one may be tough.

• Can you count to 7?

GREAT!

• THE ONLY PRERESIQUITE FOR WRITING ELECTRON CONFIGURATION IS THE ABILITY TO READ, COUNT TO 7, AND MEMORIZE s, p, d, f!!!

• FINALLY, SOMETHING EASY!!!!! SOMETHING YOU HAVE BEEN DOING SINCE YOU HAVE BEEN 5!

1s

2s

3s

4s

2p

3p

4p

3d

4d

sp

d

f

1234567

OK, so we’re going to use arrows pointing up or down to represent the electrons. Can you guess into which box the first electron would go given that it is attracted to the nucleus?

1 2

1 2 3 4 5 6 7 8 9 10

1 2 3 4 5 6 7 8 9 10 11 12 13 14

1 2 3 4 5 6

5s

+

1s

2s

3s

4s

2p

3p

4p

3d

4d

sp

d

f

1s1

1234567

That’s right: it goes in the 1s sublevel. And its el. config is 1s2. Notice in the table above where H is – in the area designated as 1s. So where does the next electron go?

1 2

1 2 3 4 5 6 7 8 9 10

1 2 3 4 5 6 7 8 9 10 11 12 13 14

1 2 3 4 5 6

5s

+

1s

2s

3s

4s

2p

3p

4p

3d

4d

sp

d

f

1s2

1234567

1 2

1 2 3 4 5 6 7 8 9 10

1 2 3 4 5 6 7 8 9 10 11 12 13 14

1 2 3 4 5 6

5s

If you were thinking it went in the 2s, then you forgot that each orbital can hold up to two electrons. Note how He is right here in the area designated as 1s2 and so its el. config. is 1s2.+

1s

2s

3s

4s

2p

3p

4p

3d

4d

sp

d

f

1s2 2s1

1234567

1 2

1 2 3 4 5 6 7 8 9 10

1 2 3 4 5 6 7 8 9 10 11 12 13 14

1 2 3 4 5 6

5s

Now that the 1s is filled, the next electron goes in the next sublevel – the 2s. Again note how Li is in 2s1.Its full el. conf. is 1s2 2s1. What is Be’s el. conf?+

1s

2s

3s

4s

2p

3p

4p

3d

4d

sp

d

f

1s2 2s2

1234567

1 2

1 2 3 4 5 6 7 8 9 10

1 2 3 4 5 6 7 8 9 10 11 12 13 14

1 2 3 4 5 6

5s

Is this what you were thinking? Good. Now look at the periodic table above, what comes after the 2s sublevel?

The 2p sublevel. So what will the next el. conf. be?+

1s

2s

3s

4s

2p

3p

4p

3d

4d

sp

d

f

1s2 2s2 2p1

1234567

1 2

1 2 3 4 5 6 7 8 9 10

1 2 3 4 5 6 7 8 9 10 11 12 13 14

1 2 3 4 5 6

5s

Is this what you were thinking? Notice how B is in the 2p1 spot.

So its full el. conf. is 1s2 2s2 2p1. What’s next?+

1s

2s

3s

4s

2p

3p

4p

3d

4d

sp

d

f

1s2 2s2 2p2

1234567

1 2

1 2 3 4 5 6 7 8 9 10

1 2 3 4 5 6 7 8 9 10 11 12 13 14

1 2 3 4 5 6

5s

Is this what you were thinking? Notice how C is in the 2p2 spot. So its el. conf. is 1s2 2s2 2p2

Notice also how when we fill a sublevel…+

1s

2s

3s

4s

2p

3p

4p

3d

4d

sp

d

f

1s2 2s2 2p3

1234567

1 2

1 2 3 4 5 6 7 8 9 10

1 2 3 4 5 6 7 8 9 10 11 12 13 14

1 2 3 4 5 6

5s

…we put one electron in each orbital until the sublevel is half filled…

+

1s

2s

3s

4s

2p

3p

4p

3d

4d

sp

d

f

1s2 2s2 2p4

1234567

1 2

1 2 3 4 5 6 7 8 9 10

1 2 3 4 5 6 7 8 9 10 11 12 13 14

1 2 3 4 5 6

5s

… and then we go back and start pairing offThis is called “Hund’s Rule, but it also referred to as the bus seat rule. Can you figure out why?+

1s

2s

3s

4s

2p

3p

4p

3d

4d

sp

d

f

1s2 2s2 2p5

1234567

1 2

1 2 3 4 5 6 7 8 9 10

1 2 3 4 5 6 7 8 9 10 11 12 13 14

1 2 3 4 5 6

5s

Look at F. It’s just one electron away from having filled 2p sublevel…

And it’s just one square away from the end of the 2p block.+

1s

2s

3s

4s

2p

3p

4p

3d

4d

sp

d

f

1s2 2s2 2p6

1234567

1 2

1 2 3 4 5 6 7 8 9 10

1 2 3 4 5 6 7 8 9 10 11 12 13 14

1 2 3 4 5 6

5s

And then Ne has a completely filled outer level. Na is next. Can you guess where the next electron is going to go?+

1s

2s

3s

4s

2p

3p

4p

3d

4d

sp

d

f

1s2 2s2 2p6 3s1

1234567

1 2

1 2 3 4 5 6 7 8 9 10

1 2 3 4 5 6 7 8 9 10 11 12 13 14

1 2 3 4 5 6

5s

That’s right: in the 3s sublevel. Right now, write down in your notebook what you think the next three el configs will be. +

1s

2s

3s

4s

2p

3p

4p

3d

4d

sp

d

f

1s2 2s2 2p6 3s2

1234567

1 2

1 2 3 4 5 6 7 8 9 10

1 2 3 4 5 6 7 8 9 10 11 12 13 14

1 2 3 4 5 6

5s

Did you get this one right?

+

1s

2s

3s

4s

2p

3p

4p

3d

4d

sp

d

f

1s2 2s2 2p6 3s2 3p1

1234567

1 2

1 2 3 4 5 6 7 8 9 10

1 2 3 4 5 6 7 8 9 10 11 12 13 14

1 2 3 4 5 6

5s

How about Al’s? See how Al is in the 3p1 spot on the per table

and its el config ends with 3p1+

1s

2s

3s

4s

2p

3p

4p

3d

4d

sp

d

f

1s2 2s2 2p6 3s2 3p2

1234567

1 2

1 2 3 4 5 6 7 8 9 10

1 2 3 4 5 6 7 8 9 10 11 12 13 14

1 2 3 4 5 6

5s

Now just advance through the next 23 slides, but as you do, make sure you are understanding+

1s

2s

3s

4s

2p

3p

4p

3d

4d

sp

d

f

1s2 2s2 2p6 3s2 3p3

1234567

1 2

1 2 3 4 5 6 7 8 9 10

1 2 3 4 5 6 7 8 9 10 11 12 13 14

1 2 3 4 5 6

5s

Exactly what is going on… how the el configs simply follow the sequence of the periodic table.+

1s

2s

3s

4s

2p

3p

4p

3d

4d

sp

d

f

1s2 2s2 2p6 3s2 3p4

1234567

1 2

1 2 3 4 5 6 7 8 9 10

1 2 3 4 5 6 7 8 9 10 11 12 13 14

1 2 3 4 5 6

5s

Your goal by the end of this slide show is to be able to write el configs for any element using just the periodic table – and your brain!+

1s

2s

3s

4s

2p

3p

4p

3d

4d

sp

d

f

1s2 2s2 2p6 3s2 3p5

1234567

1 2

1 2 3 4 5 6 7 8 9 10

1 2 3 4 5 6 7 8 9 10 11 12 13 14

1 2 3 4 5 6

5s

+

1s

2s

3s

4s

2p

3p

4p

3d

4d

sp

d

f

1s2 2s2 2p6 3s2 3p6

1234567

1 2

1 2 3 4 5 6 7 8 9 10

1 2 3 4 5 6 7 8 9 10 11 12 13 14

1 2 3 4 5 6

5s

+

1s

2s

3s

4s

2p

3p

4p

3d

4d

sp

d

f

1s2 2s2 2p6 3s2 3p6 4s1

1234567

1 2

1 2 3 4 5 6 7 8 9 10

1 2 3 4 5 6 7 8 9 10 11 12 13 14

1 2 3 4 5 6

5s

+

1s

2s

3s

4s

2p

3p

4p

3d

4d

sp

d

f

1s2 2s2 2p6 3s2 3p6 4s2

1234567

1 2

1 2 3 4 5 6 7 8 9 10

1 2 3 4 5 6 7 8 9 10 11 12 13 14

1 2 3 4 5 6

5s

+

1s

2s

3s

4s

2p

3p

4p

3d

4d

sp

d

f

1s2 2s2 2p6 3s2 3p6 4s2 3d1

1234567

1 2

1 2 3 4 5 6 7 8 9 10

1 2 3 4 5 6 7 8 9 10 11 12 13 14

1 2 3 4 5 6

5s

+

1s

2s

3s

4s

2p

3p

4p

3d

4d

sp

d

f

1s2 2s2 2p6 3s2 3p6 4s2 3d2

1234567

1 2

1 2 3 4 5 6 7 8 9 10

1 2 3 4 5 6 7 8 9 10 11 12 13 14

1 2 3 4 5 6

5s

+

1s

2s

3s

4s

2p

3p

4p

3d

4d

sp

d

f

1s2 2s2 2p6 3s2 3p6 4s2 3d3

1234567

1 2

1 2 3 4 5 6 7 8 9 10

1 2 3 4 5 6 7 8 9 10 11 12 13 14

1 2 3 4 5 6

5s

+

1s

2s

3s

4s

2p

3p

4p

3d

4d

sp

d

f

1s2 2s2 2p6 3s2 3p6 4s2 3d4

1234567

1 2

1 2 3 4 5 6 7 8 9 10

1 2 3 4 5 6 7 8 9 10 11 12 13 14

1 2 3 4 5 6

5s

+

1s

2s

3s

4s

2p

3p

4p

3d

4d

sp

d

f

1s2 2s2 2p6 3s2 3p6 4s2 3d5

1234567

1 2

1 2 3 4 5 6 7 8 9 10

1 2 3 4 5 6 7 8 9 10 11 12 13 14

1 2 3 4 5 6

5s

+

1s

2s

3s

4s

2p

3p

4p

3d

4d

sp

d

f

1s2 2s2 2p6 3s2 3p6 4s2 3d6

1234567

1 2

1 2 3 4 5 6 7 8 9 10

1 2 3 4 5 6 7 8 9 10 11 12 13 14

1 2 3 4 5 6

5s

+

1s

2s

3s

4s

2p

3p

4p

3d

4d

sp

d

f

1s2 2s2 2p6 3s2 3p6 4s2 3d7

1234567

1 2

1 2 3 4 5 6 7 8 9 10

1 2 3 4 5 6 7 8 9 10 11 12 13 14

1 2 3 4 5 6

5s

+

1s

2s

3s

4s

2p

3p

4p

3d

4d

sp

d

f

1s2 2s2 2p6 3s2 3p6 4s2 3d8

1234567

1 2

1 2 3 4 5 6 7 8 9 10

1 2 3 4 5 6 7 8 9 10 11 12 13 14

1 2 3 4 5 6

5s

+

1s

2s

3s

4s

2p

3p

4p

3d

4d

sp

d

f

1s2 2s2 2p6 3s2 3p6 4s2 3d9

1234567

1 2

1 2 3 4 5 6 7 8 9 10

1 2 3 4 5 6 7 8 9 10 11 12 13 14

1 2 3 4 5 6

5s

+

1s

2s

3s

4s

2p

3p

4p

3d

4d

sp

d

f

1s2 2s2 2p6 3s2 3p6 4s2 3d10

1234567

1 2

1 2 3 4 5 6 7 8 9 10

1 2 3 4 5 6 7 8 9 10 11 12 13 14

1 2 3 4 5 6

5s

+

1s

2s

3s

4s

2p

3p

4p

3d

4d

sp

d

f

1s2 2s2 2p6 3s2 3p6 4s2 3d10 4p1

1234567

1 2

1 2 3 4 5 6 7 8 9 10

1 2 3 4 5 6 7 8 9 10 11 12 13 14

1 2 3 4 5 6

5s

+

1s

2s

3s

4s

2p

3p

4p

3d

4d

sp

d

f

1s2 2s2 2p6 3s2 3p6 4s2 3d10 4p2

1234567

1 2

1 2 3 4 5 6 7 8 9 10

1 2 3 4 5 6 7 8 9 10 11 12 13 14

1 2 3 4 5 6

5s

+

1s

2s

3s

4s

2p

3p

4p

3d

4d

sp

d

f

1s2 2s2 2p6 3s2 3p6 4s2 3d10 4p3

1234567

1 2

1 2 3 4 5 6 7 8 9 10

1 2 3 4 5 6 7 8 9 10 11 12 13 14

1 2 3 4 5 6

5s

+

1s

2s

3s

4s

2p

3p

4p

3d

4d

sp

d

f

1s2 2s2 2p6 3s2 3p6 4s2 3d10 4p4

1234567

1 2

1 2 3 4 5 6 7 8 9 10

1 2 3 4 5 6 7 8 9 10 11 12 13 14

1 2 3 4 5 6

5s

+

1s

2s

3s

4s

2p

3p

4p

3d

4d

sp

d

f

1s2 2s2 2p6 3s2 3p6 4s2 3d10 4p5

1234567

1 2

1 2 3 4 5 6 7 8 9 10

1 2 3 4 5 6 7 8 9 10 11 12 13 14

1 2 3 4 5 6

5s

+

1s

2s

3s

4s

2p

3p

4p

3d

4d

sp

d

f

1s2 2s2 2p6 3s2 3p6 4s2 3d10 4p6

1234567

1 2

1 2 3 4 5 6 7 8 9 10

1 2 3 4 5 6 7 8 9 10 11 12 13 14

1 2 3 4 5 6

5s

+

1s

2s

3s

4s

2p

3p

4p

3d

4d5s

sp

d

f

1s2 2s2 2p6 3s2 3p6 4s2 3d10 4p6 5s1

1234567

1 2

1 2 3 4 5 6 7 8 9 10

1 2 3 4 5 6 7 8 9 10 11 12 13 14

1 2 3 4 5 6

+

1s2

2s2

3s2

4s2

5s2

6s2

7s2

2p6

3p6

4p6

5p6

6p6

3d10

4d10

5d10

6d10

4f14

5f14

1

2

3

4

5

6

7

So, the pattern for reading the electron configurations right off the periodic table is this:If you are wanting to write the electron configuration for any element, just follow this pattern and remember to stop at the element you’re representing.

1s2

2s2

3s2

2p6

3p5

1

2

3

4

5

6

7

For example, Cl (#17) which is right here on the table:

So the answer would be 1s2 2s2 2p6 3s2 3p5

The short cut would be: [Ne]3s2 3p5

1s2

2s2

3s2

4s2

2p6

3p6

3d8

1

2

3

4

5

6

7

Or how about Ni (#28)

1s2 2s2 2p6 3s2 3p6 4s2 3d8

Short cut: [Ar] 4s2 3d8

1s2

2s2

3s2

4s2

5s2

6s2

2p6

3p6

4p6

5p6

6p3

3d10

4d10

5d10

4f14

1

2

3

4

5

6

7

Let’s try Bi (#83)

1s2 2s2 2p6 3s2 3p6 4s2 3d10 4p6 5s2 4d10 5p6 6s2

4f14 5d10 6p3 (don’t forget the 4f14!)Short cut: [Xe]6s2 4f14 5d10 6p3