Covalent bonds Chemical bond that results from the sharing of TWO electrons

Covalent bonds

Covalent Bonds Balancing Act of Attractive and Repulsive Forces Electrostatic Forces

Diatomics Hydrogen Nitrogen Oxygen Fluorine Chlorine Bromine Iodine H 2 N 2 O 2 F 2 Cl 2 Br 2 I 2

Are you Listening???? What is a covalent bond? How is it different from an Ionic Bond. Covalent bonds are the chemical bonds formed when atoms SHARE electrons. T CovalentIonic Share electronstransfer electrons

Lewis Structures Atomic symbol with valence electrons around it H H

Lewis Structures 1. Find atomic symbol 2. Determine number of valence electron 3. Place electrons alone first 4. Pair up if needed F 7 valence electrons

Lewis Structure Practice H O N C H O N C

Valence Electrons Tell us # e to share Paired electrons NOT shared FF

Lewis Structure Practice H O N C H O N C

Number of Bonds HH O C N HH HH H H H HH σ

What is a single covalent bond? Why does it form? A single covalent bond is the sharing of two electrons by two atoms with each atom contributing one electron to the shared paired. They form to allow atoms to become stable by having access to 8 electrons!!!!

Orbitals and Bonding Sigma bonds can form between 2s orbitals 1s, 1p 2p Bonding orbital – region where bonding electrons are likely to be found

Multiple Covalent Bonds O O N N DOUBLE BOND TRIPLE BOND

Make Me some π

Write this down!!! Why do multiple covalent bonds form? They form that so that atoms can have access to 8 electrons. In other words so that atoms can obtain a NOBLE GAS CONFIGURATION

Bond Length Distance between nuclei at the MAX attraction Units are usually Å 1Å = m1m = Å Convert 0.05 m to Å Convert 1.46 Å to m Convert 2.65 Å to nm Convert 123 pm to Å 5.0*10 8 Å 1.46* m 26.5 nm 1.23 Å

Bond Strength HH O O N N

Lowest Energy Distance Distance ENERGYENERGY

Lowest Energy Distance Distance ENERGYENERGY

Lowest Energy Distance Distance ENERGYENERGY

Lowest Energy Distance Distance ENERGYENERGY Bond Dissociation Energy

Almost Done F21.43 Å O21.21 Å N21.10 Å 159 kJ/mol 498 kJ/mol 945 kJ/mol

How is bond length related to bond dissociation energy? The shorter the bond the larger the dissociation energy.

Energy Energy is always released when making a chemical bond Energy is always added when breaking a chemical bond Need to look at TOTAL ENERGY of a RXN

Endo vs Exo Exothermic – energy is flowing out Endothermic – energy is flowing into