covalent bonding

Covalent Bonding

Ms. KellerWTHS Chemistry

General Covalent-nessCovalent bond- bond that results

from the sharing of valence electrons

Diatomic molecule: elements that are bonded to itself in nature

Br I N Cl H O F

General Covalent stuff con’t

Types of bonds: Single = sigma bond Double = sigma bond + pi bond Triple = sigma bond + 2 pi

bonds

Bonds are electron pairs that are being sharedLone Pairs- unshared pairs of electrons

Lone pair

Bond LengthsBond Length- distance between the

nuclei of the 2 atoms that are bonded when they are the most attracted to one another

Determined by:◦Size of the atoms◦How many electron pairs are shared

(how many bonds there are) As # of bonds , the bond length

Energy and BondsBond dissociation energy- amount

of energy needed to break a specific covalent bond

Breaking bonds ALWAYS requires the addition of energy

Endothermic vs. Exothermic

Naming Binary Molecular Compounds!

1st element + 2nd element with the ending -ide

Use the following prefixes to indicate the number of the atoms of each element present:1. mono 6. hexa2. di 7. hepta3. tri 8. octa4. tetra 9. nona5. penta 10. deca

Naming Acids!Binary method:

◦1. prefix = hydro (to represent hydrogen)

◦2. root of 2nd element◦Change ending to –ic acid

◦Ex) HF = hydrofluoric acid

Naming Acids!Oxyacids: Acids that contain oxygen

Don’t put Hydro in for hydrogen!If the group ends in –ate, it changes to –icIf the group ends in –ite, it changes to –ousATE –IC, ITE –OUSThrow acid on the end

Ex) H2SO4 = Sulfuric AcidEx) H2SO3 = Sulfurous Acid

Let’s Practice Naming…C2O4

NO2

C4H10

SO3

N2O5

HClHBrH3PO4

HClO2

Writing FormulasJust read the name! The prefix tells you how many of

each element you have – this is your subscript!

◦Ex) carbon tetrafluoride = CF4

Because tetra=4 and it’s attached to fluorine, it becomes the subscript

How to Draw Lewis Structures for Covalent Bonding

1. Add up all valence electrons

2. Add up all octets that need to be filled (octet=2 for H)

3. Subtract step 1 from step 2

4. Divide value from step 3 by 2 to get how many bonds are in the molecule

Ex) CH4

How to Draw Lewis Structures for Covalent Bonding

Some hints for how they fit together:

Element closest to the left is usually the central atom

Hydrogen is always terminal (on the end)