Methods of predicting the arrangement and location of electrons in atoms

Electron Arrangement

A. Lewis Dot Structures

valence electrons – e– in an atom’s outermost orbitals (in highest energy level) available for bonding; determine the chemical properties of an element

electron-dot structure – consists of element’s symbol surrounded by dots that represent the atom’s valence e–

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sp

d (n-1)

f (n-2)

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B. Electron Congifuration

C. Johannesson

S 16e-

Valence Electrons

Core Electrons

1s2 2s2 2p6 3s2 3p4

C. Notations

Longhand Configuration

Shorthand Configuration Go up one row and over to the Noble

Gas. Fill in the remaining e- in each sublevel

like normal.

S 16e- [Ne] 3s2 3p4

[Ar] 4s2 3d10 4p2

Example - Germanium

White Board Examples

Helium (He)Fluorine (F)Nitrogen (N)Aluminum (Al)Sulfur (S)

Homework

Do the Lewis dot structure and long and short hand electron configuration for the following elements: Magnesium (Mg) Silver (Ag) Gold (Au) Bromine (Br) Europium (Eu)

D. Orbital Diagrams

This configuration gives more detail as to where the electrons are located.

orbital – region of high probability of finding e–; maximum of 2 e– per orbital s sublevel = 1 orbital (2 e–) p sublevel = 3 orbitals (6 e–) d sublevel = 5 orbitals (10 e–) f sublevel = 7 orbitals (14 e–)

Ex: Oxygen

E. General Rules

Pauli Exclusion Principle

Each orbital can hold TWO electrons

with opposite spins.

E. General Rules

Hund’s Rule

Within a sublevel, place one e- per orbital before pairing them.

E. General Rules

Aufbau Principle

Electrons fill the lowest energy orbitals first.

White Board Examples

Indium (In)Selenium (Se)Sulfur (S)Aluminum (Al)

Homework

Do the orbital diagram for the following elements: Magnesium (Mg) Bromine (Br) Phosphorus (P) Neon (Ne)