The Address of the Electrons

� Each electron has a set of four numbers, called quantum numbers

� Each electron has a different set of numbers ¡  No 2 electrons in the same atom can have the

same 4 quantum number ¡  Pauli exclusion principle.

� Attraction between protons in nucleus and electron in cloud.

� Takes energy for electron to pull away from nucleus

� Lower energy levels closer to nucleus � Higher energy levels farther from nucleus � Described by integers

¡  1 is closest to nucleus (lowest enegry

� Show the shape of the area that a electron is most likely moving around.

� 4 types ¡  s, p, d, and f ¡  Each requires a different amount of energy for an

e- to remain ¡  Lowest energy is s ¡  Highest energy is f

� Described by their energy level number and their subshell type level

� Example ¡  S orbital in energy level 2---2s

� An area of high probability where an electron is located

� The specific orientation of the shape of the subshell

� S ¡  Has one orbital, holds 2 electrons

� P ¡  Has three orbitals, holds 6 electrons

� D ¡  Has five orbitals, holds 10 electrons

� F ¡  Has 7 orbitals, holds 14 electrons

� The arrangement of electrons in an atom � 3 methods of writing electron configuration

¡  Boxes and arrows ¡  Spectroscopic notation ¡  Noble gas notation

� From the German word "Aufbauen" which means "to build”

� Electrons will first occupy orbitals of the lowest energy level.

� Aufbau Principle � Hund’s Rule

¡  Electrons are placed in their own orbitals before doubling up

� Pauli Exclusion Principle ¡  In order for electrons to share an orbital, they

must have different spin ¡  One spin up ¡  One spin down

Sublevels

Number of electrons in the sub level 2,2,5

1s2 2s2 2p5

� Use the last noble gas that is located in the periodic table right before the element.

� Write the symbol of the noble gas in brackets. � Write the remaining configuration after the

brackets. � Ex: Fluorine: [He] 2s2 2p5