electrons in atoms s p d f youtube - the atom song
TRANSCRIPT
Electrons in Atoms
S
P
d
f
YouTube - The Atom Song
Early models of the Atom
J.J.Thomson’s Plum Pudding Model
Dalton’s Model
Rutherford’s model of the Atom
If all atoms looked the same then,,,,,
they could not explain why different elements had different properties
Problems with Rutherford:Rutherford theory does not explain what the electrons are doing
Does not explain the experimental phenomenon of atomic spectra
Atomic Spectraatomic spectra- The range of
characteristic frequencies of electromagnetic radiation that are readily absorbed and emitted by an atom.
Neon lights…..
http://www.upscale.utoronto.ca/PVB/Harrison/Spectra/Spectra.html
Rydberg
Could mathematically explain atomic spectra – but no theory to apply it to….
Rydberg
Rydberg could mathematically explain the atomic spectra,(by treating particles as waves WHAT?- we will get to that later) but it wasn’t attached to any theory or model
Rydberg Equation
Rydberg developed this equation to explain Hydrogen’s atomic spectra
RH=109677.57 cm-1
This behavior could only be explained if the atoms gave off light in specific amounts of energy………we needed a better model of the atom to explain this…….
Idea!
Bohr Model of Atom1913
Protons and Neutrons in Nucleus Electrons were arranged in Energy Levels at
fixed positions around the Nucleus He thought- different elements had
different electron arrangements and therefore different properties
Atomic Structure Review Nucleus
Protons ( made of 3 quarks) Neutrons (made of 3 quarks)
Electron Cloud Area where electrons are located Electrons are arranged in energy levels
They found out that electrons don’t stay in one energy level, they can move from one energy level to another depending on how much energy they have
Ground state – where the electron usually is.
Excited state – when the electron has absorbed a quantum of energy is in a higher energy level
Amount of energy needed to move an electron from one energy level to another is called a QUANTUM of ENERGY
Electrons make QUANTUM LEAPS or SHIFTS
energy levels are not equally spaced.
different amounts of energy are needed to make the shift
The higher the energy level, the less energy it takes to make the shift to a higher level.
Once they shift up….Electrons do not hold energyEnergy quickly released (same
amount as absorbed) as packet of energy called a photon
Electron falls back down to Ground State
Einstein and Planck
• these transitions(shifts) usually involve the absorption or emission of a quantum of light.
• They named the packets of light energy called photons.
Golf ball demonstration
The frequency of light emitted by an element separates into discrete lines to give an atomic emission spectra
The emission spectra of an element is like a fingerprint-used to identify elements in stars
The Atomic Emission Spectrum: an explanation
http://chemistry.bd.psu.edu/jircitano/periodic4.html
Niels Bohr, was born 7 October 1885 in Copenhagen, Denmark and died in 1962, was the Danish physicist whose investigations of atomic structure earned him the 1922 Nobel Prize for physics. Bohr's work helped solve the problems classical physics could not explain about the nuclear model of the atom. He postulated that electrons moved in fixed orbits around the atom's nucleus, and he explained how they emitted or absorbed energy. Bohr attended the University of Copenhagen (1903-11), then studied for a time under ernest Rutherford in Manchester, england. By 1916 he was back at the University of Copenhagen as a professor of physics, and in 1920 he became the first director of the Institute of Theoretical Physics. Bohr's Institute became a gathering place for the world's top physicists, and he is considered one of the foremost scientists of modern physics, along with Albert Einstein, erwin Schrödinger and enrico Fermi. During World War II Bohr avoided Adolf Hitler's army and left Denmark in 1943; he ended up in the United States and was sent to Los Alamos, New Mexico to join Robert Oppenheimer and others working to develop the atomic bomb. After the war he returned to Denmark and spent the rest of his career advocating the peaceful uses of atomic energy.
What we learn from the Bohr atom
Electrons Travel in Fixed energy levels-energy levels are not equal-ladder- can only go from rung to rung, can’t stand in between…..energy is QUANTIZED (separate into levels)
electrons usually in the ground state- lowest energy state
Remember the mint? Nitrogen atoms in the air absorb the energy emitting UV light. Wintergreen molecules absorb the energy and release as bluish light
When an atom absorbs energy, electrons move into higher energy levels when they return to lower energy levels they lose energy and emit light in the form of photons at specific frequencies
But what is a photon? To be continued….
Electrons continue to “shift up” and “shift down”, giving off a steady flow of photons
These photons form a light wave.
n=1
n=2
n=3
n=4
Spectrum
UV
IR
Vi s ible
Ground State
Excited State
Excited StateExcited State unstable and drops back down
•Energy released as a photon
•Frequency proportional to energy drop
Excited State
But only as far as n = 2 this time
SummaryElectron normally in Ground State
Energy supplied [ as heat or
electricity]
Electron jumps to higher energy level
Now in Excited State
Unstable
Drops back to a lower level
Electromagnetic radiation
********Light acts as ********Light acts as both particles both particles and wavesand waves
Parts of a Wave
Use the Greek letter “nu” Use the Greek letter “nu” ( ( ) ) = wavelength= wavelength
Amplitude measures intensity amount of energy in the waveIn Sound = loudness
In light = brightness
Frequency
Number of waves per second ( )
Determines type of light produced measured in Hertz (Hz) (cycles per sec)
Electromagnetic Spectrum – a chart of all the light waves arranged by frequency
Electromagnetic SpectrumElectromagnetic Spectrum
Wavelength and frequency are inversely proportional
Long wavelength Long wavelength small frequency small frequencylow low energyenergyShort wavelength Short wavelength high frequencyhigh frequencyhigh high energyenergy
Frequency, Wavelength and Amplitude
Same frequency- different amplitude
Same amplitude- different frequency
If the light wave given off has the frequency visible light, color is seen
Photons have different amounts of energy
different energies= different frequencies= different wavelengths=
different colors of light
• = cc
c c = velocity of light = 3.00 x 10= velocity of light = 3.00 x 1088 m/sec m/sec
Wavelength x frequency = velocity of light
Velocity (speed) of light
What is the wavelength ( of a light wave that has a frequency of 3 x 1018 meters?
What type of electromagnetic wave is it?(see pg.139) *c c = velocity of light = 3.00 x 10= velocity of light = 3.00 x 1088 m/sec m/sec
• = cc
Ans. 1 x 10-10m Ans. X-rays
What is the frequency ( ) of a wave that has a wavelength of 1 x 10-4 m?What type of wave is it? • = cc
Ans. 3 x 10Ans. 3 x 1012 12 m/secm/sec Ans. microwaveAns. microwave
Electrons and LightCurrent model of atom comes from study of light
Physicists would heat up different elements until they glowed, and then direct the light through a prism...
White light passing through a prism
Continuous spectrum of white light
White Light made of all the various wavelengths and
frequencies of visible light ROYGBIV Red – Low energy Violet-High energy Called a continuous spectrum
Excited Gases Excited Gases & Atomic & Atomic StructureStructure
When physicists heated gases and observed the light they produced…….
didn't see the whole rainbow. only bright lines of certain colors
?
Line Emission Spectra Line Emission Spectra of Excited Atomsof Excited AtomsLine Emission Spectra Line Emission Spectra of Excited Atomsof Excited Atoms
Excited atoms emit light of only certain wavelengths
The wavelengths of emitted light depend on the arrangement of the electrons in the atom.
Spectrum is not continuousA unique line emission spectrum is formed
Spectrum of Spectrum of Excited Hydrogen GasExcited Hydrogen Gas
Spectral Lines Each element has its own unique number of electrons
and produces own set of spectral lines Since electrons absorb a different quanta of energy
as they jump up energy levels, they release photons of varying energies, producing different frequencies of light
They are the “fingerprints” of an element.
Line Spectra of Other ElementsLine Spectra of Other Elements
Let’s look at the spectral lines produced by various gases…..
http://jersey.uoregon.edu/vlab/elements/Elements.html
Atomic Line Emission Atomic Line Emission Spectra and Niels BohrSpectra and Niels BohrAtomic Line Emission Atomic Line Emission Spectra and Niels BohrSpectra and Niels Bohr
Bohr’s model of the Bohr’s model of the atom was based on atom was based on an understanding of an understanding of thethe LINE EMISSION LINE EMISSION SPECTRASPECTRA of excited of excited atoms.atoms.
Niels BohrNiels Bohr
(1885-1962)(1885-1962)
HowStuffWorks Videos "100 Greatest Discoveries: Signature Light of Elements"
Models of the Atom From Dalton to Schroedinger
Quantum Mechanical Model of the Atom
Probability of finding an electron in a certain position is based on its allowed energies
Energy levels divided into sublevels
Sublevels divided into orbitals
Electrons
electrons usually in the ground state- lowest energy state
But where are they ?
Electron ConfigurationElectron configuration gives us directions to where an electron is most likely located
Schroedinger Equation A mathematical formula in which there
is more than one solution Leads to a probability of finding an
electron in a particular place – firefly These solutions are known as quantum
numbers – which give probable locations of the electron
Arrangement of Arrangement of Electrons in AtomsElectrons in AtomsArrangement of Arrangement of Electrons in AtomsElectrons in Atoms
Electrons in atoms are arranged asElectrons in atoms are arranged as
LEVELSLEVELS (n) (n)
SUBLEVELSSUBLEVELS (l) (l)
ORBITALSORBITALS (m (mll))
ENERGY LEVELS
MAIN LOCATION OF ELECTRONS AROUND ATOMS
THE HIGHER THE ENERGY, THE GREATER THE DISTANCE FROM THE NUCLEUS
ENERGY LEVELS
Also called energy states or energy shells.
They are referred to by the principal quantum numbers 1, 2, 3, 4, 5, 6 and 7
ENERGY SUBLEVELS
An energy level is made up of one or more sublevels (subshells)
An energy level can have s, p, d and f sublevels.
Sublevels are shown as “blocks” on the Periodic Table
Current maximum electron numbers for each energy level
• Energy level 1 =(s) 2 electrons• Energy level 2 = (s,p) 8 electrons• Energy level 3 = (s,p,d) 18 electrons• Energy level 4 = (s,p,d,f) 32 electrons• Energy level 5 = (s,p,d,f) 32 electrons• Energy level 6 = (s,p,d) 18 electrons• Energy level 7 =(s) 2 electrons
ELECTRON ORBITALS
Each sublevel is made up of one or more electron orbitals
Orbitals are 3-Dimensional areasThe orbitals in sublevels are referred
to as s orbitals,p orbitals, d orbitals and f orbitals
Each orbital can only hold 2 electronsWithin an orbital the electrons spin
in opposite directions so they don’t repel each other
Each orbital (area) has a specific shape. (remember they are 3- dimensional)
Orbitals and Orbitals and their Shapestheir Shapes
Types of Orbitals Types of Orbitals
s orbitals orbital p orbitalp orbital d orbitald orbital
S orbital
p Orbitalsp Orbitalsp Orbitalsp Orbitals
The three p orbitals lie 90The three p orbitals lie 90oo apart in spaceapart in space
P orbital
YouTube - s and p orbitals, orbitais s e p
The shapes and labels of the five 3d orbitals.
“D” Orbitals
YouTube - atomic d orbitals
f Orbitalsf Orbitalsf Orbitalsf Orbitals
f sublevel with 7 orbitalsf sublevel with 7 orbitals
F orbitals
YouTube - Electron Orbitals - s,p & d
s orbitalss orbitals d orbitalsd orbitals
Number ofNumber oforbitalsorbitals
Number of Number of electronselectrons
11 33 55
22 66 1010
p orbitalsp orbitals f orbitalsf orbitals
77
1414
How many electrons can be in a sublevel?How many electrons can be in a sublevel?
Remember: A maximum of two electrons can Remember: A maximum of two electrons can be placed in an orbital.be placed in an orbital.
Orbital Diagrams
• Rules to Remember: – Aufbau principle: fill lower
energy levels first– Pauli Exclusion: two
electrons in each orbital with opposite spin.
– Hund’s Rule: One electron in One electron in each orbital of an energy each orbital of an energy level, then you can pair them level, then you can pair them upup
Orbital DiagramsGraphical representation of an
electron configurationEach arrow represents one
electronShows spin(opposite arrow)
and which orbital the electron is in within a sublevel
Must put 1 electron in each orbital of a sublevel before pairing them up
Exceptions- d4 and d9, two electrons in each orbital, etc.
LithiumLithiumLithiumLithium
Group 1AGroup 1AAtomic number = 3Atomic number = 31s1s222s2s11 ---> 3 total electrons ---> 3 total electrons
1s
2s
3s3p
2p
CarbonCarbonCarbonCarbonGroup 4AGroup 4AAtomic number = 6Atomic number = 61s1s2 2 2s2s2 2 2p2p22 ---> ---> 6 total electrons6 total electrons
Here we see for the first time Here we see for the first time
HUND’S RULEHUND’S RULE. When . When placing electrons in a set of placing electrons in a set of orbitals having the same orbitals having the same energy, we place them singly energy, we place them singly as long as possible.as long as possible.1s
2s
3s3p
2p
Lanthanide Element Lanthanide Element ConfigurationsConfigurations
4f orbitals used for Ce - Lu and 5f for Th - Lr
4f orbitals used for Ce - Lu and 5f for Th - Lr
1s
2s2p
3s3p
3d 4s4p
energy
Oxygen (O)Chromium (Cr)Krypton (Kr)
Draw these orbital diagrams!
Why do “d” and “f” orbitals fill in out of order? d and f orbitals require LARGE amounts
of energy So…. the electrons fill in the next “s”
sublevel before they fill in the previous “d” or “f” sublevels because it’s a lower energy sublevel.
Electron Configurations
2p4
Energy LevelEnergy Level
SublevelSublevel
Number of Number of electrons in electrons in the sublevelthe sublevel
1s1s22 2s 2s22 2p 2p66 3s 3s22 3p 3p66 4s 4s22 3d 3d1010 4p 4p66 5s 5s22 4d 4d1010 5p 5p66 6s6s22 4f 4f1414…… etc.etc.
Electron Configurations Show how the electrons are arranged Periodic Table can be used as a “road
map” to map out electron configurations
Parts of the Periodic Table
Columns = Groups or Families-Have same # of valence electrons-Have similar properties
Rows = Periods or Series-Have same number of energy levels
Electrons and the Periodic Table You can use the periodic table to
determine how the electrons are arranged (electron configuration)
The Periodic Table shows sublevels and orbitals
Orbitals and the Orbitals and the Periodic TablePeriodic Table
s orbitals orbital(1orbital)(1orbital) p orbitalsp orbitals
(3 orbitals)(3 orbitals)
d orbitalsd orbitals(5 orbitals)(5 orbitals)
f orbitalsf orbitals(7 orbitals)(7 orbitals)
1
2
3
4
5
6
7
6
7
group # = # valence (outside) e-
d p
f
sRow=
# shells
1
2
3
4
5
6
7
6
7
peri
od
# =
# e
- sh
ells
1A2A
3B4B5B6B7B8B8B8B1B2B
3A4A5A6A7A8Agroup # = # valence e-
d
f
3d
4d
5d
6d
4f
5f
Subshells d and f are “special”
Let’s Try It!Write the electron configuration for
the following elements:HLiNNeKZnPb
Principal Quantum number (energy level)
sublevels Orbitals per sublevel
Orbitals per energy level
Number of electrons per sublevel
Total Electrons in energy level
1 s 1 1 2 2
2 s
p
1
3
4
2
6
8
3 s
p
d
1
3
5
9
2
6
10
18
4 s
p
d
f
1
3
5
7
16
2
6
10
14
32
Ws. Electron Configurations
Diagonal Rule The diagonal rule is a memory device that
helps you remember the order of the filling of the orbitals from lowest energy to highest energy
Order of Electron Subshell Filling:It does not go “in order”
1s2
2s2 2p6
3p6
4p6
5p6
6p6
7p6
3s2
4s2
5s2
6s2
7s2
3d10
4d10
5d10
6d10
4f14
5f14
1s2 2s22p6 3p63s2 4s2 4p65s23d10 5p66s24d10 6p67s25d104f14 7p66d105f14
Diagonal Ruless
s 3p 3ds 3p 3d
s 2ps 2p
s 4p 4d 4fs 4p 4d 4f
s 5p 5d 5f 5g?s 5p 5d 5f 5g?
s 6p 6d 6f 6g? 6h?s 6p 6d 6f 6g? 6h?
s 7p 7d 7f 7g? 7h? 7i?s 7p 7d 7f 7g? 7h? 7i?
11
22
33
44
55
66
77
Steps:Steps:
1.1. Write the energy levels top to bottom.Write the energy levels top to bottom.
2.2. Write the orbitals in s, p, d, f order. Write Write the orbitals in s, p, d, f order. Write the same number of orbitals as the energy the same number of orbitals as the energy level.level.
3.3. Draw diagonal lines from the top right to the Draw diagonal lines from the top right to the bottom left.bottom left.
4.4. To get the correct order, To get the correct order,
follow the arrows!follow the arrows!
By this point, we are past By this point, we are past the current periodic table the current periodic table so we can stop.so we can stop.
Shorthand NotationA way to abbreviating electron configurations
Since we are only concerned about the outermost electrons, we can skip to places we know are completely full (noble gases), and then finish the configuration
Shorthand NotationStep 1: Find the closest noble gas to the atom (or ion), WITHOUT GOING OVER the number of electrons in the atom (or ion). Write the noble gas in brackets [ ].
Step 2: Finding the next energy level after noble gas
Step 3: Resume the configuration until it’s finished.
Shorthand Notation Chlorine
Longhand is 1s2 2s2 2p6 3s2 3p5
You can abbreviate the first 10 electrons with a noble gas, Neon. [Ne] replaces 1s2 2s2 2p6
The next energy level after Neon is 3So you start at level 3 on the diagonal rule (all levels start with s) and finish the configuration by adding 7 more electrons to bring the total to 17
[Ne] 3s2 3p5
Practice Shorthand NotationWrite the shorthand notation
for each of the following atoms:
ClKCaIBi
Electron Configurations
A list of all the electrons in an atom (or ion) Used to determine valence electrons.valence electrons. Valence electrons are the electrons in the Valence electrons are the electrons in the
outermost energy level.outermost energy level. The number of valence electrons determines
bonding capabilities Valence electrons are the electrons in the last last
“s” and “p” sublevels.“s” and “p” sublevels.
1s1s22 2s 2s22 2p 2p66 3s 3s22 3p 3p66 4s 4s22 3d 3d1010 4p 4p66 5s 5s22 4d 4d1010 5p 5p66 6s 6s22 4f 4f1414…… etc.etc.
Valence ElectronsValence ElectronsValence ElectronsValence ElectronsElectrons are divided between Electrons are divided between core core and and valence valence
electronselectronsB 1sB 1s22 2s 2s22 2p 2p11
Core = 1sCore = 1s22 , , valence = 2svalence = 2s22 2p 2p11
Br [Ar] Br [Ar] 4s4s22 3d 3d1010 4p 4p55
Core = [Ar] 3dCore = [Ar] 3d1010 , , valence = 4svalence = 4s22 4p 4p55
Electron Dot DiagramsThe The core electronscore electrons are represented are represented by the by the symbol symbol of the atom.of the atom.
The The valence electronsvalence electrons are are represented with a represented with a dotdot..
Rules of the GameRules of the GameRules of the GameRules of the Game
Atoms like to either empty or fill their outermost Atoms like to either empty or fill their outermost level.level. Since the outer level contains two s Since the outer level contains two s electrons and six p electrons (d & f are always in electrons and six p electrons (d & f are always in lower levels), the optimum number of electrons lower levels), the optimum number of electrons is eight. This is called theis eight. This is called the octet rule.octet rule.
Let’s Review….Let’s Review…. S sublevels have 1 orbital P sublevels have 3 orbitals D sublevels have 5 orbitals F sublevels have 7 orbitals
EACH ORBITAL CAN ONLY HOLD 2 ELECTRONS (in opposite spin)
The End !!!!!!!!!!!!!!!!!!!