Transcript Covalent Bonds

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
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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
mono
di
tri
tetra
penta
hexa
hepta
octa
nona
deca
# of atoms
(1)
(2)
(3)
(4)
(5)
(6)
(7)
(8)
(9)
(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 formula
1. SiO2 = Silicon dioxide
2. PBr3 = Phosphorus tribromide
3. CI4 = Carbon tetraiodide
4. N2O3 = Dinitrogen trioxide
Writing Formulas for Covalent
Compunds
Writing formulas from names
1. Carbon Dioxide
CO2
2. Dinitrogen Pentoxide
N2O5
3. Triphosphorus monosulfide
P3S
4. Sulfur Monobromide
SBr