Covalent Bonds

Bonding Atoms - Review

• Why do atoms bond?• Each atom wants a full outermost energy level

• How do they do this?– By gaining, losing, or sharing valence electrons to

achieve octet rule aka: “being happy or stable”– Gives each atom an electron configuration similar

to that of a noble gas

Types of Bonding

• Ionic Bond– Gives / Takes Electrons– One atom will give an electron to another atom

• Covalent Bond– Share electrons– Two elements will share electrons between them so

they are both “happy” / stable

• Polar Bond– We aren’t going to cover

Covalent Bonds• A chemical bond in which two atoms share a pair

of valence electrons• Always formed between nonmetals

Steps to Covalent Bonds

• Step 1: Draw the Bohr Model OR the Lewis Dot Diagram

• Step 2: Put circles around the electrons that are being shared

• Step 3: Redraw the diagrams replacing the circled dots with lines

• Step 4: Write the compound

Step by Step Covalent Example• Hydrogen and Hydrogen– Step 1: Draw the Bohr/ Lewis Dot Diagram

– Step 2: Put a circle around the shared electrons

– Step 3: Replace the circle with a solid line

– Step 4: Write the completed compound

H2

Practice Problem• Hydrogen and Oxygen– Hydrogen needs 1 additional electron to fill its

outer shell• It only have 1 to share• THEY MUST SHARE EQUAL NUMBERS

– Oxygen needs 2 more electrons to fill its outer shell

– ** This tells us that one hydrogen isn’t enough

Hydrogen and Oxygen• Step 1/2:

• Step 3:

• Step 4:

Covalent Bonds

• Single Bonds– One electron is shared between 2 elements

• Double Bonds– Two electrons are shared between 2 elements

• Triple Bonds– Three electrons are shared between 2 elements

Double Bond Example• Oxygen and Oxygen– Both have 6 electrons and NEED 2 more– They can both share 2

• Step 1/2

• Step 3

• Step 4

Two Types of Covalent Bonds

• Diatomic– Two of the same elements are bonded– Aren’t found alone. Always found together or

bonded to other elements– ONLY the following• H O N Cl Br I F

• Polytomic– More than 2 elements are bonded together

https://www.youtube.com/watch?v=QIfTT-_-xLo

Characteristics of covalent compounds• Low melting and boiling points• Solubility and electrical conductivity• Do NOT dissolve well in water. • At room temperature covalent substances are

gases, or liquids or low melting point solids.

Naming Covalent Compounds

• Look at the 1st Element– If only 1 – just use the element name– If more than 1 – use the correct prefix

• Look at the 2nd Element– If its an element use the chart above– If it’s a compound use the compound chart

Naming Covalent Compounds• Prefix System

prefix # of atomsmono (1)di (2)tri (3)tetra (4)penta (5)hexa (6)hepta (7)octa (8)nona (9)deca (10)

Polyatomic Ions Cont.• Common Polyatomic Ions

Name the following compounds

1. SiO2

2. PBr3

3. CI4

4. N2O3

Naming Covalent Compounds Cont.

Naming covalent compounds from formula1. SiO2 = Silicon dioxide

2. PBr3 = Phosphorus tribromide

3. CI4 = Carbon tetraiodide

4. N2O3 = Dinitrogen trioxide

Writing Formulas for Covalent Compunds

Writing formulas from names1. Carbon Dioxide CO2

2. Dinitrogen Pentoxide N2O5

3. Triphosphorus monosulfide P3S

4. Sulfur Monobromide SBr