Electron Configuration Unit 4 - Electrons in Atoms

Atomic Model Review zBohr – Electrons are found in orbitals around the nucleus zDe Broglie – Electrons behave like waves zConsensus – Electrons are found in clouds around the nucleus

Quantum Model zThere are several energy levels occupied by electrons zEnergy levels are represented by a positive integer zAs the distance from the nucleus increases, the number increases

Quantum Model Nucleus n=1 n=2 n=3

Quantum Model zThere are several types of orbitals that can occur in an energy level zOrbitals have a specific shape and are represented by a lowercase letter

Quantum Model zs-orbital – SPHERICAL – 1 orbital

Quantum Model zp-orbital – BOWTIE – 3 orbitals

Quantum Model zd-orbital – CLOVERLEAF – 5 orbitals

Quantum Model zf-orbital – COMPLICATED! – 7 orbitals

Quantum Model zDifferent energy levels have different types of orbitals. z1 st energy level - s orbital z2 nd energy level – s & p orbitals z3 rd energy level – s, p, & d orbitals z4 th energy level – s, p, d, & f orbitals

Quantum Model – Hog Hilton 3p ___ ___ ___ 3s ___ 2p ___ ___ ___ 2s ___ 1s ___

I KNOW HOW MANY ELECTRONS AN ATOM HAS… BUT HOW DO THE ELECTRONS FIT INTO THE ORBITALS??

General Rules zPauli Exclusion Principle yEach orbital can hold TWO electrons with opposite spins.

General Rules zAufbau Principle yElectrons fill the lowest energy orbitals first. y“Lazy Tenant Rule”

Aufbau Principle

RIGHT WRONG General Rules zHund’s Rule yWithin a sublevel, place one e - per orbital before pairing them. y“Empty Bus Seat Rule”

O 8e - zOrbital Diagram zElectron Configuration 1s 2 2s 2 2p 4 Notation 1s 2s 2p

Practice… zHelium (He) zCarbon (C) zSodium (Na) zPhosphorus (P) zNitrogen (N) zAluminum (Al) zCalcium (Ca) zArgon (Ar)

Notation zThere’s an easier way to figure out electron configurations zWe can use our handy-dandy, trusty periodic table

© 1998 by Harcourt Brace & Company s p d f Periodic Patterns

s-block1st Period 1s 1 1st column of s-block C. Periodic Patterns zExample - Hydrogen

Periodic Table Patterns zPeriod # (Row #) = Energy Level y Subtract 1 for d y Subtract 2 for f

Use the periodic table… zHelium (He) zCarbon (C) zSodium (Na) zPhosphorus (P) zIron (Fe) zZirconium (Zr) zCalcium (Ca) zIodine (I)

Notation – A Shorter Way! zNoble gas – column on the far right of the periodic table zLast energy level is full of electrons yLike a full floor of the Hog Hilton zExamples yHe – 1s 2 yAr – 1s 2 2s 2 2p 6 3s 2 3p 6

Notation zWe can abbreviate the full energy levels by using noble gases zExample - Sulfur

zShorthand Configuration S 16e - S16e - [Ne] 3s 2 3p 4 1s 2 2s 2 2p 6 3s 2 3p 4 Notation zLonghand Configuration

[Ar]4s 2 3d 10 4p 2 Shorthand Notation zExample - Germanium

Shorthand Notation zSulfur (S) zTin (Sn) zBarium (Ba) zSilver (Ag)

S 16e - Valence Electrons Core Electrons 1s 2 2s 2 2p 6 3s 2 3p 4 Valence Electrons zThe electrons found in the outermost shell or level

Periodic Table Patterns zGroup # (Column #) = Total # of valence electrons y True for s & p block y d & f blocks are weird…

Lewis Dot Diagrams zRepresents the number and placement of valence electrons in an atom

Lewis Dot Diagrams zRemember your electron rules yBe single before you double! yElectrons want to be far apart! ySince we’re only looking at the s & p blocks, the total number will be 8 or less (except H & He)

Lewis Dot Diagrams zExample – OXYGEN zHow many valence electrons? zWrite the element symbol zFill in the dots

zFull energy level zFull orbital (s, d, f) zHalf-full orbital (p, d, f) Stability

zElectron Configuration Exceptions yCopper EXPECT :[Ar] 4s 2 3d 9 ACTUALLY :[Ar] 4s 1 3d 10 yCopper gains stability with a full d-orbital. Stability

zElectron Configuration Exceptions yChromium EXPECT :[Ar] 4s 2 3d 4 ACTUALLY :[Ar] 4s 1 3d 5 yChromium gains stability with a half-full d-orbital. Stability

Stability – Ion Formation zIon = charged atom; not neutral zAtoms gain or lose electrons to become more stable zMore stable = noble gas configuration

Ground State zEnergy level that an electron normally occupies zState of lowest energy for an electron zHogs are lazy & don’t like to climb stairs

Ground State zWhen an electron temporarily occupies an energy level GREATER than its ground state, it is in an EXCITED state yExcitement occurs when an electron absorbs a PHOTON (light emitting particle – Einstein vs. Newton) zSo when an electron RETURNS to its ground state, it will emit a PHOTON

Ground State  Excited State

Excited State  Ground State

Here’s the cool part! zThe color of the emitted light depends on the amount of energy in the photon!

Electromagnetic Spectrum zAmount of energy depends on wavelength

Electromagnetic spectrum zSpeed of light = wavelength x frequency zC = λ v zStreet lights containing sodium vapors emit an intense yellow light at a wavelength of 589 x If light travels at the speed of 3.00 x 10 8 m/s, what is the frequency of this intense yellow light?

Flame Test zCan be used to identify unknown metals

Fume Hood