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Entry Task: October 15th MondayQuestion:
Does it take more energy for the painter to get to the middle of the
ladder or the top?
You have 5 minutes!!
Agenda:
Sign off on Ch. 5 section 2 reading notesHomework: Ch. 5 section 2 worksheet
I can…
• Compare the Bohr and quantum mechanical models of the atom.
• Identify the relationships among a hydrogen atom’s energy levels, sublevels, and atomic orbitals
Ch. 5-2
Quantum Theory
and
the Atom
BOHR MODEL OF THE ATOM (AS PARTICLES)
Define ground state.
It’s the lowest allowable energy state of an atom.
BOHR MODEL OF THE ATOM (AS PARTICLES)
Summarize Bohr’s model of the atom
His atomic model resembles a “solar system”
Electrons closest to the nucleus has the lowest energy level
Electrons can move to different energy levels when they get excited
When they go back to their original level, they release energy as light (photon)
BOHR MODEL OF THE ATOM (AS PARTICLES)
What happens when an electron at ground state gets energy from an outside source?
It moves to a higher energy level
BOHR MODEL OF THE ATOM (AS PARTICLES)
What happens when the electron drops from a high-energy orbit?
It releases energy- emits a photon corresponding to the difference between the energy levels associated with the two orbits.
E higher energy orbit – E lower energy orbit = E photon = hv
BOHR MODEL OF THE ATOM (AS PARTICLES)
Why was Bohr’s model of the atom incorrect?
This was “great” for hydrogen but it does not explain the rest of the elements
It also did not account for chemical behaviors
The Quantum Mechanical Model of the Atom
Finish the sentence. DeBroglie proposed that –• “If waves…
can have particlelike behavior, could the opposite also be true
The Quantum Mechanical Model of the Atom
Wavelength= 6.626 x 10-34 J
Mass velocity
The deBroglie equation predicts…
That all moving particles have wave characteristics
The Heisenberg Uncertainty Principle
• He concluded that it is impossible to make any measurements (observations) on an object (electrons) without disturbing the object.
• From this, it is impossible to know precisely both the velocity and position of a particle at the same time.
Read the analogy of the helium balloon and using a photon to locate an electron. How did this concept connect with the Heisenberg uncertainty principle?
Schrödinder wave equation• Taking Bohr’s hydrogen atom’s electron and treating it
like a wave, he come up with a new atomic model- quantum mechanical model of the atom
• Atomic orbital- By using probability- a 3-D cloud where there is a high probability as to the location of an electron at a given moment.
Hydrogen’s Atomic Orbitals
Define principal quantum numbers-
Just like Bohr who assigned quantum numbers to electron orbit but these numbers indicate relative sizes and energies of the atomic orbitals
Hydrogen’s Atomic Orbitals
Define principle energy levels (n)
As (n) increases, the orbital becomes larger, the electron spends more time farther from the nucleus, and the atom’s energy level increases.
Principle energy levels are major energy levels.
Hydrogen’s Atomic Orbitals
Define energy sublevels AND provide their labels
Principle energy levels have sub energy levels
The first energy level (n1) has 1 sublevel
The second energy level (n2) has 2 sublevels
The third energy level (n3) has 3 sublevels
The fourth energy level (n4) has … guess..
s
s, p
s, p, d
s, p, d, f
Hydrogen’s Atomic Orbitals
What is the shape of the s orbital?__________
What is the shape of the p orbital?__________
What about d and f’s orbitals shapes?________
How many electrons- at most- can be in each orbital?___
Spherical
dumbbell
Have different shapes
2
Hydrogen’s Atomic Orbitals
For orbital 2p sublevel, why are there subscripts on the end? Example 2px, 2py, and 2pz.
The subscripts x, y, z are designate the orientation of the p orbitals along the x, y, and z coordinate axes
The area where an electron can be found,the orbital,
is defined mathematically,but we can see it as a specific shape
in 3-dimensional space…
For this presentation, thenucleus of the atom is atthe center of the three axes.
x
y
zThe 3 axes represent3-dimensional space
The first energy level has how many sublevels?
What shape is this sublevel?
1
s
OR 1s
The “1s” orbital is asphere, centeredaround the nucleus
The second energy level has how many sublevels?
What shapes are in this sublevel?
2
s and p
Lets start with 2s
The 2s orbital is alsoa sphere.
The 2s electrons have a higher energy than the 1selectrons. Therefore, the 2selectrons are generally moredistant from the nucleus,making the 2s orbital largerthan the 1s orbital.
1s orbital
2s orbital
The s orbitals are spheres
Don’t forget:
an orbital is the shape of the space where there is a high probability of finding electrons
The second energy level has how many sublevels?
What shapes are in this sublevel?
2
s and p
Now lets look at the p orbitals
There are three2p orbitals
The three 2p orbitalsare orientedperpendicularto each other
This is orbital (2px)
x
y
z
This isone 2p orbital
(2py)
x
y
z
Lastly, the third 2p orbital(2pz)
x
y
z
Don’t forget:
an orbital is the shape of thespace where there is a highprobability of finding electrons
x
y
z
2px
x
y
z
2px and 2pz
x
y
z
The three 2p orbitals,2px, 2py, 2pz
x
y
z
once the1s orbitalis filled,
once the 2sorbital isfilled,
the 2p orbitalsbegin to fill
each 2p orbitalintersects the2s orbital andthe 1s orbital
each 2p orbitalgets one electronbefore pairing begins
once each 2p orbitalis filled with a pairof electrons, then
Hydrogen’s Atomic Orbitals
• For energy level 3, it consists of 3 sublevels, 3s, 3p, and 3d. How many orbitals are in the 3d sublevel?
The 3d sublevel has 5 orbitals
Hydrogen’s Atomic Orbitals
The first 4orbitals have what shape(see fig 5-16)?
What is the deal with the fifth, dz2 orbital?
Double dumbbell (clover shaped)
Weird dumbbell with a collar
The third energy level has how many sublevels?
What shapes are in this sublevel?
3
s, p, and d
the 3s orbitalgets the nexttwo electrons
the 3s electronshave a higher energythan 1s, 2s, or 2pelectrons,
so 3s electrons aregenerally foundfurther from thenucleus than 1s,2s, or 2p electrons
Hydrogen’s Atomic Orbitals
How many sublevels does the 4th principle energy level have?
How many orbitals are in this sublevel? What is the letter that represents this orbital arrangement?
Has 4 sublevels- s. p. d and f
7 orbitals “f”
The timeline shows the development of atomic models from 1913 to 1932.