chemical bonding

1. Chemical Bonding
Chapter 1
Interactions of Matter

2. REVIEW
 Identify the 4 atoms whose models are on the
bulletin board.
 How did you identify these elements?

3. Electron Arrangements
Energy Level Maximum
Number of
Electrons
1 2
2 8
3 8 (then 10 more
later)
Remember
electrons
arrange in
energy levels
outside the
nucleus.

4. Electron Dot Diagrams
 Show ONLY outer level electrons
 Also called Lewis diagrams
1. Begin with the element’s symbol
2. Use the PT to determine the number of
outer level electrons
3. Place up to 2 dots per side for a total of up
to 8 electrons
 Put the first 2 dots together on one side,
then put single dots on the remaining sides
until you have to pair them

5. Electron Dot Diagrams
 Ex: 1 electron
X

6. Electron Dot Diagrams
 Ex: 2 electrons
X

7. Electron Dot Diagrams
 Ex: 3 electrons
X
Choose a clockwise or counterclockwise
direction and fill empty sides with an
electron before pairing any electrons.

8. Electron Dot Diagrams
 Ex: 4 electrons
X
Choose a clockwise or counterclockwise
direction and fill empty sides with an
electron before pairing any electrons.

9. Electron Dot Diagrams
 Ex: 5 electrons
X
Choose a clockwise or counterclockwise
direction and fill empty sides with an
electron before pairing any electrons.

10. Electron Dot Diagrams
 Ex: 6 electrons
X
Choose a clockwise or counterclockwise
direction and fill empty sides with an
electron before pairing any electrons.

11. Electron Dot Diagrams
 Ex: 7 electrons
X
Choose a clockwise or counterclockwise
direction and fill empty sides with an
electron before pairing any electrons.

12. Electron Dot Diagrams
 Ex: 8 electrons
X
THIS IS THE MOST ELECTRONS THAT EVER ARE
INCLUDED IN ELECTRON DOT DIAGRAMS.

13. Electron Dot Diagrams
 Time to practice what you’ve learned
 For the following elements, create electron dot diagrams
using M&M’s as electrons. Be sure to write large size
symbols on your paper.
 YUM, but no eating allowed until all your work is checked
and is correct!
aluminum potassium argon oxygen
phosphorus silicon barium iodine
BRING IN YOUR ATOMIC MODEL TOMORROW!

14. CHEMICAL BONDING
 The number of electrons in the ____________ energy
level determines whether an atom will form bonds.
 These electrons are also called ___________ electrons.
 Atoms bond to get a ________ outer level.
 For all E levels beyond the first, the outermost E level is
considered to be full if it contains ______ (#) electrons.
 The first E level is full with ____ (#) electrons.
 Why are noble gases nonreactive?

15. CHEMICAL BONDING
 Atoms bond by __________, ____________, or
___________ electrons to have a filled outermost energy
level containing 8 valence electrons.
 ___(#) types of bonds hold atoms together.
1. IONIC BOND- force of electrostatic attraction between 2
oppositely charged ______.
 Ions form when electrons are _________________.
2. COVALENT BOND- force of attraction between nuclei of atoms
and the electrons _______________ by the atoms.
 Neutral atoms held by covalent bonds are called
__________________.
3. METALLIC BOND- force of attraction between a ____________
charged metal ion and the electrons in a metal.

16. IONIC BONDS
 Chem 4 Kids example
METALS
•have a low/high number of valence electrons.
•metals lose/gain electrons when bonding.
•form positive/negative ions.
NONMETALS
•have a low/high number of valence electrons.
•lose/gain electrons when bonding.
•form positive/negative ions.
•ions end in –ide

17. IONIC BONDS

18. Naming IONIC compounds
Binary compounds- contain only 2 elements
 negative ion ends in -ide
 Ex: Name NaCl
 Ex: Name AlF3
 Ex: Name Li2S
 compounds are neutral so use subscripts to make (+)=(-)
 Write the chemical formula for
 Ex: strontium sulfide
 Ex: potassium oxide
 Ex: calcium chloride
 Ex: barium nitride

19. Naming IONIC compounds
Binary compounds- containing transition elements
 Transition metals- the charge is in parenthesis
following the name of the metal except for Ag, Cd,
and Zn (see PT)
 ex: chromium (II) chloride
 ex: iron (III) oxide
 Ex: NiF2 vs. NiF
 Ex: CrI4 vs. CrI2

20. Naming IONIC compounds
What about compounds with more than 2 elements
 Look on page 159 for polyatomic ions
 Polyatomic ions- groups of atoms that are bonded
together with a charge
 Usually end in -ate
 Ex: BaSO4
 Ex: potassium phosphate
 Ex: iron (III) carbonate

21. IONIC BONDS- metal ion + nonmetal ion
CHARACTERISTICS OF IONIC COMPOUNDS
•Hard, brittle solids at room temp
•High melting and boiling points
•Ions are held in a crystal lattice
•Conduct electricity when dissolved in H2O

22. Quick Review
1. Barium sulfide
2. Aluminum carbonate
3. NaClO3
4. SiO2
5. Dinitrogen pentoxide

23. COVALENT BONDS
 Unlike ionic bonds with transferred electrons, covalent
bonds __________ electrons.
IONIC BOND COVALENT BOND

24. COVALENT BONDS
 Unlike ionic bonds that generally form between metals
and nonmetals, covalent bonds form between
________________.
 Classify the bonds as ionic or covalent
1. Na-Cl
2. H-O
3. C-O
4. Ca-F
5. N-N
6. Cr-S NOTE: Group 14
has a strange e-dot
diagram

25. COVALENT BONDS
 Use electron dot diagrams to model molecules
 Examples:
1. H2
2. H2O
3. NH3
4. Cl2

26. COVALENT BONDS
 Some molecules are simple with only one element
 7 elements are not found in nature as atoms
 They always are found in pairs- called diatomic
N2 O2 F2
Cl2
Br2
I2
And H2 (always the exception)

27. COVALENT BONDS
 EXAMPLES OF COVALENT COMPOUNDS
 water
 plastic
 sugar
 Gasoline oils & fats
 CHARACTERISTICS OF COVALENT COMPOUNDS
1. Do NOT conduct an electrical current
2. Low melting and boiling points
3. Lightweight molecules: generally gases and liquids at
room temp
4. Heavier molecules: generally solids at room temp

28. COVALENT COMPOUNDS
 Naming covalent compounds involves using prefixes to
indicate the number of atoms in the formula.
 Website w/prefixes and rules

29. COVALENT COMPOUNDS
• When atoms share electrons, they don’t
always share them equally.
• Nonpolar covalent compounds:
share e- equally
• Will not conduct an electrical
current at all
• All diatomic molecules are
nonpolar
• Polar covalent compounds: share e-
unequally
• Can conduct an electrical current

30. COVALENT COMPOUNDS
• Polarity affects how chemicals mix.
• “Like dissolves like.”
• Nonpolar compounds mix with other
nonpolar compounds.
• Ex:
• Polar compounds mix with other polar
compounds.
• Ex:
• Nonpolar compounds will not mix with
polar compounds.
• Ex:
• How does this affect how soap is made?

31. METALLIC BONDS
 EXAMPLES CONTAINING METALLIC BONDS
 Cu, Fe
 Alloys- mixtures of metals
 EX: brass, bronze, steel
 CHARACTERISTICS OF METALS
1. Malleable & ductile
2. Good conductors
 “sea of electrons” allows metals to be shaped without
breaking
 Close metal atoms have overlapping outer E levels
 Valence electrons can move freely between positive metal
ions