Chemical Bonds
● Molecules are made up of more than one atom.
● Compounds are made up of more than one element.
● When atoms combine to make molecules, they form chemical bonds.
● Types of Bonds:● Ionic Bonds● Covalent Bonds● Metallic Bonds
Types of Chemical Bonds
● Ionic Bond
● Covalent Bond
● Metallic Bond
Relative Strengths of Bonds
Ionic Bond Strongest
Covalent Bond
Metallic Bond Weakest
Chemical Bonding is represented using Lewis Dot Diagrams.
REMINDERS: (do not need to write)
● Valence electrons (dots) are placed around the four sides of the element symbol.
● Electrons (dots) begin to pair up only when no more single spaces are left.
● Single dots show where the atom can form a chemical bond.
***Lewis Dot Structures
Ionic Bond: an attractive force between a metal and a nonmetal.
Structure of Ionic Bonds
● Crystalline in Structure – Form lattices● Relatively high melting and boiling points● Brittle – the lattice can be broken if enough external force
applied
● Conduct electricity only when melted or dissolved in water
● Many (not all) are soluble in water – those that dissolve in water form solutions that conduct electricity are electrolytes (particles that conduct electricity in solution)
Oxidation Numbers
Bond Formation:
opposite charges attract
•occurs when electrons are transferred •forms ions that attract each other
Ionic Bonding
● Transfer of electrons● From metal → non-metal● Results from the electrostatic charge between a
metal ion (cation - positive charge) and a non-metal ion (anion – negative charge)● This means that we are transfering from positive to negative
oxidation numbers
● The overall number of negative and positive charges must be the same – aka they must cancel out and equal zero
Time to Practice
You need a Bonding Basics handout
We will be using this for the entire unit.
You are completing “Basics” and “Section B” today
Test Analysis
● Pick up a test analyis sheet● Pick up your bubble sheet from the
back● Find two different colors
I will put the key on the board
No
Ions
!
+4-4
-1
What does a chemical formula tell you?
1) Number and type of atoms.
2) Type of ions.
3) Formula mass
Write this slide! The title and 1-3
1)Write the metal first, then the nonmetal. Al3+ O2-
2) Switch the charge values except if they can be reduced. Al2
3+ O32-
Notice: The sum of the charges equals zero.2(+3) + 3(-2) → (+6) + (-6) = 0
3) Write the formula without the charges. Al2O3
*****PRACTICE MAKES PERFECT!!!
Writing Binary Formulas: The Steps
**Write this slide!**
Do this for the 6 ionic bonds in your pink packet.
Name the metal, then the nonmetal; change ending to –ide.
KI potassium iodide
Ca3N2 calcium nitride
BaCl2 barium chloride
NaH sodium hydride
**Write this slide!**
Practice: Binary Ionic Compounds
1) CaBr2 = Calcium Bromide2) Na2S3) AgCl4) SrBr25) Al2O36) Li2S
**Write this slide!**
Practice: Binary Ionic Compounds
1) CaBr22) Na2S3) AgCl4) SrBr25) Al2O36) Li2S
Calcium Bromide
Sodium Sulfide
Silver Chloride
Strontium Bromide
Aluminum Oxide
Lithium Sulfide
Writing Binary Ionic Compounds
● Sodium chloride → NaCl● Calcium bromide →● Potassium nitride →● Aluminum sulfide →● Barium iodide →● Lithium Oxide →
**Write this slide!**
Writing Binary Ionic Compounds
● Sodium chloride →● Calcium bromide →● Potassium nitride →● Aluminum sulfide →● Barium iodide →● Lithium Oxide →
NaClCaBr2
K3N
Al2S3
BaI2Li2O
Polyatomic IonsThis chart is on the back of your orange table OR on the
white periodic table
Combining Polyatomic Ions
● More than one CAPITAL LETTER next to each other
● Will end in “-ate” or “-ite”● Exceptions: Hydroxide, Ammonium
2+1-1-
If more than one polyatomic ion, use ( ).
**Write this slide!**
Aluminum Sulfate
● For every 2 aluminum ions (Al3+), you need 3 sulfate ions (SO4
2-). ● The combined
charges add up to zero.
**Write the example below!**
Practice: Write the Compound
*remember, first element is USUALLY on P. Table, Second is polyatomic ion because it ends in -ate, -ite or is hydroxide
● Potassium nitrate ___________ ● Sodium phosphate _________
● Calcium hydroxide _________
● Ammonium sulfate _________● Both of these are on the polyatomic ion chart!
**Write this slide!**
Practice: Write the Compound
● Potassium nitrate = KNO3 ● Sodium phosphate = Na3PO4
● Calcium hydroxide = Ca(OH)2
● Ammonium sulfate = (NH4)2SO4
Metallic Bonding
Metallic Bonding