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!!

Agenda: Sign off on Ch. 5 section 2 reading notes Homework: 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= x 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 2p x, 2p y, and 2p z. 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, the nucleus of the atom is at the center of the three axes. x y z The 3 axes represent 3-dimensional space

The first energy level has how many sublevels? What shape is this sublevel? 1 s OR 1s

The “1s” orbital is a sphere, centered around 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 also a sphere. The 2s electrons have a higher energy than the 1s electrons. Therefore, the 2s electrons are generally more distant from the nucleus, making the 2s orbital larger than 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 three 2p orbitals The three 2p orbitals are oriented perpendicular to each other

This is orbital (2p x ) x y z

This is one 2p orbital (2p y ) x y z

Lastly, the third 2p orbital (2p z ) x y z

Don’t forget: an orbital is the shape of the space where there is a high probability of finding electrons

x y z

2p x x y z

2p x and 2p z x y z

The three 2p orbitals, 2p x, 2p y, 2p z x y z

once the 1s orbital is filled,

once the 2s orbital is filled,

the 2p orbitals begin to fill

each 2p orbital intersects the 2s orbital and the 1s orbital

each 2p orbital gets one electron before pairing begins

once each 2p orbital is filled with a pair of 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, dz 2 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 orbital gets the next two electrons the 3s electrons have a higher energy than 1s, 2s, or 2p electrons,

so 3s electrons are generally found further from the nucleus than 1s, 2s, or 2p electrons

Hydrogen’s Atomic Orbitals How many sublevels does the 4 th 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.