BELLWORK 10/26/17 What is a photon? Is light a particle or a wave? Is an electron a particle or a wave?

Electrons as Waves Bohr’s work in describing the hydrogen line emission spectrum led scientists to hypothesize that electrons (like light) existed as particles and waves.

De Broglie - 1924 Performed experiments that proved that electrons had wave-like properties; as well as existing as particles. Proof: 1. Electrons can only exist at specific frequencies, just like waves. 2. The frequencies correspond to specific energy levels; just like Bohr’s Model.

Erwin Schrodinger, 1925 Quantum Mechanical Model of the Atom Developed a wave equation for describing the Probability of finding an electron in a certain region. Described the location of electrons in greater detail using a system of Quantum Numbers.

Heisenberg - 1927 If De Broglie and Schrodinger are correct and electrons exist as particles and waves, then where exactly are they found in the atom? Experiment: Used photons (packets of energy) to detect electrons. Conclusion: Because photons have the same amount of energy as electrons. Any attempt to locate an electron by hitting it with a photon knocks it off course

Heisenberg Uncertainty Principle “It is impossible to determine simultaneously both the position and velocity of an electron or any other particle.”

Images of the Quantum Model

Checkpoint Who proved that electrons could only exist at specific frequencies? What is Schrodinger known for? What does Heisenberg’s Uncertainty Principle state?

Quantum Numbers are used to describe the probable location of electrons. Principal Quantum Number (n) - describes the SIZE of the orbital or ENERGY LEVEL of the atom. Angular Momentum Quantum Number (l) or SUBLEVELS - describes the SHAPE of the orbital. (s.p,d,f) Magnetic Quantum Number (m) - describes an ORBITAL’S ORIENTATION in space. (x,y,z axis) Spin Quantum Number (s) - describes the SPIN or direction (clockwise or counter-clockwise) in which an electron spins.

Principle Quantum Number (n) or Energy Level Describes the energy levels from 1 thru 7 The lower the number, the closer the energy level is to the atom's nucleus and less energy The energy levels correspond to the periods on the periodic table. Maximum # of electrons that can fit in an energy level is given by formula 2n2

Angular Momentum Quantum Number (l) or Sub-level determines the shape of the orbitals. The number of sub-levels per energy level is equal to the energy level #. 1st energy level = 1 sublevel. 2nd energy level = 2 sublevels, (s,p) 3rd = s,p,d 4th = s,p,d,f s-orbital - shaped like spheres p-orbitals – shaped like dumb-bells d-orbitals – two dumb-bells connected f-orbitals – too complex to describe

Magnetic Quantum Number (m) or Orbitals The third of a set of quantum numbers Tells us how many orbitals there are of a sublevel and their orientation in space of a particular orbital Only two electrons can fit in an orbital To determine the number of orbitals on each energy level, use the equation n2 ((n is the energy level number)

S – orbitals only have one orientation. *holds up to 2 electrons

P - orbitals – have 3 different orientations *Holds up to 6 electrons

D - orbitals- have 5 different orientations *Holds up to 10 electrons

F – orbitals – Have 7 different orientations. *Holds up to 14 electrons

SPIN QUANTUM NUMBER (s) The fourth of a set of quantum numbers number specifying the direction of the spin of an electron around its own axis. only two electrons of opposite spin may occupy an orbit the only possible values of a spin quantum number are +1/2 or -1/2.

Principle Quantum # (n) LEVEL/SIZE 1 2 3 4 Angular Quantum # (l) ORBITAL SHAPE or SUBLEVEL s s p s p d s p d f Magnetic Quantum # (m) AXIS/ ORIENTATION or ORBITALS 1 orbital 1 3 4 total orbitals 1 3 5 9 total orbitals 1 3 5 7 16 total orbitals Spin Quantum # (s) DIRECTION OF ELECTRON SPIN 2 e- 8 e- 18 e- 32 e-

Sub-levels = Specific Atomic Orbitals There are 4 types of atomic sublevels: s, p, d and f Each of these sub-levels and their orbitals are represented on the periodic table Blue = s block Yellow = p block Red = d block Green = f block

BELLWORK 10/27/17 How many quantum numbers are assigned to each electron? Name the 4 sublevels? How many orbitals are found on the 2nd energy level? (n2) How many s, p, d, and f orbitals are there? How many electrons can the 4th energy level hold? (2n2)

Rules for Describing the Location of Electrons in an Atom 1) You must place electrons starting at the lowest energy level and work your way up. (Aufbau Principle) 2) You can only put two electrons in one orbital, with opposite spins. (Pauli Exclusion) 3) Within a particular group of orbitals like 2p or 4d, you must first put one electron in each orbital before you can put the 2nd electron in. (Hund’s Rule)

Hund’s Rule In a sublevel, every orbital gets one electron before any orbital gets a pair. Example: e- config. for carbon: 1s2 2s2 2p2 1s 2s 2p orbitals sublevel energy level

Block Table This shows the different blocks in the Periodic Table. It also shows in what order to write electron configurations (1s, 2s, 2p, 3s, 3p, 4s, 3d, 4p, 5s, 4d, 5p, 6s, 4f, 5d, 6p, 7s, 5f, 6d,7p)

PERIODIC TABLE

Orbital Diagrams Orbital diagram for hydrogen. e- config: 1s1 1s

Orbital Diagrams Show the arrangement of electrons in orbitals within an atom. Use boxes to represent orbitals in each energy level One arrow (↑) represents 1 e-. 2 arrows (↑↓) rep. 2 e-.

Orbital Diagrams Orbital diagram for helium. e- config: 1s2 1s

Hund’s Rule e- config. for oxygen: 1s22s22p4 1s 2s 2p orbitals sublevel energy level

Orbital Diagrams Orbital diagram for nitrogen. e- config: 1s2 2s2 2p3

Orbital Diagram for Bromine

Writing Electron Configuration How many electrons are there in He? Where are they located ( follow the rules) Now, let’s write down where they are located. Atom # of e- 1s 2s 2p 3s 3p 4s 3d He Be B O Mg P

YOUR TURN……. Write the electron configuration for the following elements: 1. He 2. Li 3. B 4. Ni 5. F 6. Na 7. K

The Noble Gas Configuration

Noble Gas Configuration The Noble Gases are: He, Ne, Ar, Kr, Xe, Rn Notice that each noble gas finishes a row, or energy level. Noble gas configurations take advantage of this by condensing what you have to write: Ex. He : 1s2 Ex. C : 1s2 2s2 2p2 Noble Gas Configuration for C: [He] 2s2 2p2

Noble Gas Config. – an example The normal configuration for As-(Arsenic) 1s2 2s2 2p6 3s2 3p6 4s2 3d10 4p3 Notice, the part in yellow is the same as Argon’s configuration: 1s2 2s2 2p6 3s2 3p6 The noble gas configuration will start with the gas in the row before it. [Ar] 4s2 3d10 4p3 It cuts down on a lot of writing, and that’s a good thing.

CLASSWORK Get into cooperative groups of 4 and complete the Quantum Model Tasks Cards in your groups.

EXIT TICKET………… Color your periodic tables lightly to show the location of the 4 sublevels. S Sublevel - Red P Sublevel – Yellow D Sublevel – Green F sublevel - Purple