covalent bonds. bonding atoms - review why do atoms bond? each atom wants a full outermost energy...
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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
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
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)
Naming Covalent Compounds Cont.
Naming covalent compounds from formula1. SiO2 = Silicon dioxide
2. PBr3 = Phosphorus tribromide
3. CI4 = Carbon tetraiodide
4. N2O3 = Dinitrogen trioxide