Honors Chemistry Chapter 5Electrons

The more success the quantum theory has, the sillier it looks. ~Albert Einstein, Nobel Prize in Physics, 1921.Quantum mechanics: the dreams that stuff is made of. ~unknownIf quantum mechanics has not yet profoundly shocked you, you have not yet understood it. ~Niels Bohr, Nobel Prize in Physics, 1922.

Where are electrons located?Outside the nucleus

How are they arranged?

Bohr model of electron placement

Called the planetary modelElectrons closer to the nucleus lower energy levelElectrons farther away from the nucleus higher energy level

Called the shells K, L, M, N2, 8, 18, 32 electronsStudied the emission spectrum of HydrogenSpecific colors that are emitted (given off) when an atom releases energy

Quantum StaircaseAn electron in a stable orbit will have a specific, restricted (quantitized) energy:

Niels Bohr

Max PlanckStated that the object (metal) emits energy in small, specific amounts called Quanta.Quantum is the minimum quantity of energy that can be lost or gained by an atom.Step ladder analogy

Albert EinsteinTook Plancks idea a little further.He introduced that electromagnetic radiation has a dual wave-particle nature.Light exhibits many wavelike propertiesCan also be thought of as a stream of particles

Two important concepts from Bohr:Electrons exist only in certain discrete energy levelsEnergy is involved in moving an electron from one level to another

IN REALITY, ELECTRONS DO NOT ORBIT THE NUCLEUS LIKE PLANETS ORBITING A STAR!!!!Bohrs Model

Electrons not really in planetary orbitsAre really in areas of probability called electron cloudsQuantum Model of electron placement

Quantum Mechanical ModelThis model determines the allowed energies an electron can have and how likely it is to find the electron in various locations around the nucleus

Heisenburgs Uncertainty Principle

it is not possible to know both the velocity and position of a particle at the same time

velocity = speed and direction

Orbital - 3 dimensional region around the nucleus where a particular electron can be locatedclouds - that show a region of high probability of finding an electronsize and shape of cloud depends on energies of electrons that occupy them

Principal Energy LevelsIndicates main energy level of an electron in an atomcalled shells1 = lowest 7 = highestcan be any positive integer

Sublevel Indicates the shape of an orbital

labeled s, p, d, f

s = spherep = dumbbell or figure-eightd = 4 lobesf = complicated

Orbital shapes for Sc

funky orbitals

Principal Energy LevelsAre divided into sublevelsthe number of sublevels allowed is equal to the principal energy level (n) (up to n=4)PEL = 11 sublevelPEL = 22 sublevelsPEL = 33 sublevelsPEL = 44 sublevels

Wish you were here?Well, youre not, so pay attention!

s sublevel 1 orbital allowedp sublevel 3 orbitals allowedd sublevel 5 orbitals allowedf sublevel 7 orbitals allowed

PELsublevels allowed1s2s, p3s, p, d4s, p, d, f

Each sublevel has a certain number of orbitals allowed

Sublevelorbitals alloweds 1p 3d 5f 7

Maximum of 2 e- in any orbital !

They spin in opposite directions

WAKE UP!!!!!!!!

Dont give up!

You cant escape!

I know youd rather be here, but it gets better, I promise!

Are you ready????????

Chart that follows this slide: Principal energy leveltype of sublevel#orbitals per type#orbitals per levelMax. # electrons

Principal Energy Level (pel)Type of sublevel# orbitals per type of sublevel# orbitals per peln2Maximum number of electrons per pel 2n2 1 s 1 1 2 2 s p 1 3 4 8 3 s p d 1 3 5 9 18 4 s p d f 1 3 5 7

16

32

Rules for writing electron configurationsAdd one electron at a time according to these rules:1. each added electron is placed in a sublevel of lowest energy available (Aufbau Process)2. No more than 2 electrons can be placed in any orbital (Pauli Exclusion Principle)

3. Before a second electron can be placed in any orbital, all the orbitals of the sublevel must contain at least one electron (Hunds Rule)4. No more than 4 orbitals are occupied in the outermost principal energy level of any atom. (next electron must enter the next principal energy level)

NOW!!!!We will start writing electron configurations Regular andExceptions

Stanford explanation

Atoms absorb a SPECIFIC amount of energy quantaElectrons jump up into energy levels where they really dont belongImmediately drop back and release that specific amount of energy in the form of light of specific wavelength and frequency (color)

SpectroscopyUsed to study structure of atomssubstances heatede- move to higher energy levelsfall back - release photons of energy of specific wavelengthproduce a series of spectral linesare characteristic to specific substancesused as an identifying tool

Ground state - atom where the electrons are in the lowest available energy levelsexcited state - atom has electrons that have jumped to higher energy levels

Can identify elements by the colors they produceFIREWORKS!!!Flame tests lab we will do

flame test lab!