Electron configurations According to the Wave – Mechanical Model

Definition Shows the arrangement of electrons in the atom

Sublevels of PELS 1.within an energy level, orbitals with different shapes occupy different regions, known as sublevels 2.the # of the principal energy level will identify the possible number of sublevels 3.first 4 assigned are the s, p, d, and f

S - sublevel a.s sublevels have the lowest energy b.contains one orbital c.each orbital can hold a max of 2 e - d.has spherical shape

P sublevels a.contains 3 orbitals b.Max of 6 e -, along 3 axis c.has peanut shape

D Sublevel a.contains 5 orbitals b.has double peanut shape

F sublevel a.contain 7 orbitals b.Has most energy of all sublevels

Chart of PELs and sublevels PELSublevel# orbitals# electrons

The Rules for Electron Configurations Aufbau principle – an electron occupies the lowest energy orbital that can receive it Fill order: 1s 2s2p 3s3p3d 4s4p4d4f 5s5p5d5f 6s6p6d6f 7s7p7d7f

The Aufbau principle helps us to determine the electron configuration of atoms. Write the electron configuration of an atom of Beryllium (Be) 1. Identify the number of electrons in the atom. Ex) ________

2. Begin to place electrons in the sublevels, by writing the number of electrons that will fit in each sublevel for that atom. Ex) _____________________ 1s 2s2p 3s3p3d 4s4p4d4f 5s5p5d5f 6s6p6d6f 7s7p7d7f

Subtract the number of electrons that have been placed in the sublevel from the total number of electrons in the atom (this will tell you how many electrons you have leftover). Continue placing electrons in sublevels, following the fill order, until you run out of electrons for that atom. Ex) _____________________

Configurations and the Periodic Table

Orbital Notation graphically represents the arrangement of electrons in their energy levels & sublevels Hund’s rule : electrons occupying the same orbital must have opposite spins (we’ll show that with arrows), and electrons will fill one electron per orbital (with identical spin) in a sublevel before they double up.

Write the electron configuration for N. 1s 2 2s 2 2p 3 2p______ ______ ______ Increasing 2s______ Energy 1s______

Write the electron configuration for Ne 1s 2 2s 2 2p 6 2p______ ______ ______ Increasing 2s______ Energy 1s______

Write the electron configuration for O 1s 2 2s 2 2p 4 2p______ ______ ______ Increasing 2s______ Energy 1s______

Write the electron configuration for Ti 1s 2 2s 2 2p 6 3s 2 3p 6 4s 2 3d 2 3d______ ______ ______ ______ ______ 4s______ 3p______ ______ ______ 3s______ 2p______ ______ ______ 2s______ 1s______

Valence Electrons Definition: electrons that occupy the outermost PEL of an atom -Maximum number of valence electrons is 8 Reason: result of full s and p sublevels - energy levels (clouds) begin to overlap from the 3 rd to the 4 th energy level

How many valence electrons are there in the following: Sodium: ________Argon: ________ Oxygen: ________Magnesium: ______ Carbon: ________Strontium: ______

Ions Definition: Electrically charged atoms (unequal # of protons and electrons) - formed when atoms lose or gain electrons - in order to have a complete valence energy level (stable configuration) - Possible charges are listed on the Periodic Table

Cations Def: a positively charged ion - Formed when atoms lose electrons Ex) Sodium atomSodium ion (Na +1 ) Sodium ion configuration same as Neon

Anions Def: negatively charged ions -Formed when atoms gain electrons Ex) Fluorine atomFluoride ion (F -1 ) Fluoride ion configuration same as Neon