Entry Task: October 15 th Monday Question: Does it take more energy for the painter to get to the middle of the ladder or the top? You have 5 minutes!!

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.