1. Intramolecular Forces Intermolecular Forces
Bonding
Intramolecular Forces
Intermolecular Forces

2. Chemical Bond
A force that holds groups of 2 or more atoms together to make them function as a unit

3. Why? Atoms form bonds to obtain a “noble gas configuration”
Octet Rule-
Atoms need to have 8 valence electrons

4. Types of Bonds Metallic Bonds: specific only to metals
Ionic: results from transfer of electrons
Covalent: results from sharing of electrons
Coordinate covalent bond: when one atom provides both electrons of the shared pair

5. Metallic Bonding Metallic characteristics
Occurs between like atoms of a metal in the free state
Valence e- are mobile (move freely among all metal atoms)
Positive ions in a sea of electrons
Metallic characteristics
High mp temps, ductile, malleable, shiny
Hard substances
Good conductors of heat and electricity as (s) and (l)

6. It is the mobile electrons that allow the metal to conduct electricity

7. Ionic Bonds Force of attraction between closely packed opposite ions
Atoms that lose electrons easily (metals)
Atoms that gain electrons easily (nonmetals)
Electrons are transferred from metal to nonmetal
Oppositely charged ions form and they attract each other.

8. Ionic Compounds
The ions combine in quantities that provide the stable octet for each element involved
They are electrically neutral, so the charges must balance out to zero, as we learned in our formula writing topic.

9. Properties of Ionic Compounds
Hard
Poor electrical conductors (solids)
Good electrical conductors (in molten and solution)
High melting and boiling points
Dissolve in water
Form crystalline solids

11. Ionic Lewis Diagrams Step 1 after checking that it is IONIC Step 2
Determine which atom will be the +ion
Determine which atom will be the - ion
Step 2
Write the symbol for the + ion first.
NO DOTS
Draw the e- dot diagram for the – ion
COMPLETE outer shell
Step 3
Enclose both in brackets and show each charge

12. Covalent
In covalent bonding electrons are SHARED by the nuclei of each of the atoms present
WHY?
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13. Characteristics of Covalent Compounds
Soft
Poor conductors of electricity
Poor heat conductors
Low melting point
High vapor pressures

14. Lewis Structures for Covalent

15. Covalent bonding: two types
Nonpolar
Results from EQUAL sharing
Electronegativity difference 0
Polar
Results from UNEQUAL sharing
Note electronegativity difference between 0 and 1.7

16. Using Electronegativity to determine bond polarity
H-H
H-S
H-Cl
H-O
H-F

17. Choose the More Polar Bond
A) H-P or H-C
B) O-F or O-I
C) N-O or S-O
D) N-H or Si-H

18. Lewis Structures Diagrams for bonding in molecules
Lines correspond to 2 electrons in bond
Lewis structures are representations of molecules showing all valence electrons, bonding and nonbonding.

19. Lewis Structures Keep the following in mind:
Must include all of the valence electrons from all of the atoms. The total number of electrons available in the structure is the sum of all the valence electrons from all of the atoms in a molecule
Atoms that are bonded to each other share one or more pairs of electrons
The electrons are arranged to fill the valence orbitals of that atom. This means 2 electrons for H, 8 for other elements

20. Lewis Structures A way to keep track of those valence electrons
Find the sum of valence electrons of all atoms in the substance
PCl3
(7) = 26

21. Lewis Structures A way to keep track of those valence electrons
The central atom is the least electronegative element that isn’t hydrogen (why?). Connect the outer atoms to it by single bonds.
Keep track of the electrons:
26  6 = 20

22. Writing Lewis Structures
Put eight electrons around the outer atoms (“fill their octet”)
Keep track of the electrons:
26  6 = 20  18 = 2

23. Writing Lewis Structures
Fill the octet of the central atom.
Keep track of the electrons:
26  6 = 20  18 = 2  2 = 0

24. Writing Lewis Structures
If you run out of electrons before the central atom has an octet…
…form multiple bonds until it does.

25. Lewis Structures Try drawing the Lewis structure for each molecule:
NF3 N2
CO2
SO32-
CCl4 O2 H2

26. Summary https://www.youtube.com/watch?v=KjoQHqgzda8
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