Electron Configuration Electrons in Atoms

Energy levels, sublevels and orbitals Energy level (cloud or shell) SublevelsOrbitalsNumber of electrons 1s1 s orbital2 2s, p1 s orbital 3 p orbitals 8 3s, p, d1 s orbital 3 p orbitals 5 d orbitals 18 4, 5, 6, 7s, p, d, f1 s orbital 3 p orbitals 5 d orbitals 7 f orbitals 32

s orbitals 1s 2s 3s

Three p Orbitals pxpx pzpz pypy

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

A. General Rules zAufbau Principle yElectrons fill the lowest energy orbitals first.

RIGHT WRONG A. 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 B. Notation 1s 2s 2p

zShorthand Configuration S 16e - Valence Electrons Core Electrons S16e - [Ne] 3s 2 3p 4 1s 2 2s 2 2p 6 3s 2 3p 4 B. Notation zLonghand Configuration

© 1998 by Harcourt Brace & Company s p d (n-1) f (n-2) C. Periodic Patterns

zPeriod # (Row) y indicates the highest energy level (subtract for d & f) z Group # (column) yIndicates the total # of valence e - zColumn within sublevel block y# of e - in sublevel

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

C. Periodic Patterns zShorthand Configuration yCore e - : Go up one row and over to the Noble Gas. yValence e - : On the next row, fill in the # of e - in each sublevel.

[Ar]4s 2 3d 10 4p 2 C. Periodic Patterns zExample - Germanium

zFull energy level zFull sublevel (s, p, d, f) zHalf-full sublevel D. Stability

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

zIon Formation yAtoms gain or lose electrons to become more stable. yIsoelectronic with Noble Gases.

D. Stability zIon Electron Configuration yFind the Noble Gas with the same number of electrons and write its symbol in brackets yEX: Oxygen ion  O 2- = 10 electrons y= [ Ne ] yEx: Potassium ion  K + = 18 electrons y = [Ar]

Photoelectric Effect zThe emission of electrons from a metal when light shines on the metal yonly occurs if the photons in the light have a certain minimum frequency (energy) yDifferent metals require different minimum frequencies

Line Emission Spectrum zThe lowest energy state of an atom is called the ground state zA state in which an atom has a higher potential energy than the ground state is called an excited state zWhen an excited atom returns to the ground state, it gives off energy, usually in the form of light

Line Emission Spectrum zWhen this light is shined through a prism, it is separated into a series of specific frequencies of light zThe bands of light are known as the line emission spectrum for the element Line emission spectrum for hydrogen