1. Ionic Compounds
Chemical Bonding

2. Lewis Structures
Ionic – show transfer of e-

3. Ionic Bonds Ionic – transfer of electrons
Positive and negative ions are attracted to each other
Metals and non-metals

4. Ionic Formulas
Common Ion Charges 1+ 2+ 3+ NA 3- 2- 1-

5. Ionic Formulas potassium chloride magnesium nitride
copper(II) chloride
K+ Cl- 
Mg N3- 
Cu2+ Cl- 

6. Ionic Formulas
sodium bromide
sodium oxide
iron(III) chloride

7. Covalent Bonding - True Molecules
Types of Bonds
Covalent Bonding - True Molecules
Diatomic Molecule
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8. Lewis Structures

9. Lewis Structures The center atom is the least electronegative
The number of valence electrons in the molecule is the sum of all the valence electrons of each individual atom.
Always draw lone pairs

10. Polyatomic Ions A positive ion loses electrons
NH4 has 8 valance electrons in its dot structure
A negative ion gains electrons
NO2 has 18 valence electrons.

11. Resonance Structures

13. NaCl CO2 Vocabulary CHEMICAL FORMULA IONIC COVALENT Formula Unit
Molecular
Formula
NaCl
CO2

14. NaCl NaNO3 Vocabulary COMPOUND more than 2 elements 2 elements Binary
Ternary
Compound
NaCl
NaNO3

15. Na+ NO3- Vocabulary ION 1 atom 2 or more atoms Monatomic Ion
Polyatomic
Ion
Na+
NO3-

16. Crystal Lattice

17. Properties of ionic bonds
Brittle
A force dislocates the crystal plane
Dissolve in Water dissolving NaCl
Water is a polar molecule which attracts both + and – ions
Conduct electricity if molten or dissolved
When the ions are not neutralized by bonds, the electric current passes from ion to ion.
High Melting points
Very strong bonds

18. Properties of Bonds Lattice Energy
Energy released when one mole of an ionic crystalline compound is formed from gaseous or aqueous ions

19. Energy of Bond Formation
Potential Energy Diagram
attraction vs. repulsion
no interaction
increased attraction

20. Energy of Bond Formation
Potential Energy Diagram
attraction vs. repulsion
increased repulsion
balanced attraction & repulsion

21. Energy of Bond Formation
Bond Energy
Energy required to break a bond
Bond Energy
Bond Length

22. Bond Strength vs. Length
Which is Strongest? Which is weakest? Why? LiCl, NaCl, or KCl?
Which is stronger? LiF or LiCl? Why?
Which is stronger, CaO or LiF? Why?
Which is stronger, CaO or MgO? Why?

23. Bond Energy Which is stronger? N-N or N=N Why?
N=N Multiple bonds are stronger.
Which is stronger? H-F , H-Cl, H-Br Why?
H-F Shorter bond length – higher bond energy.
How much energy is needed to break apart each of the following bonds?
HCl OH
H2O NH3 CH4

24. Bond Polarity
Most bonds are a blend of ionic and covalent characteristics.
Difference in electronegativity determines bond type.

25. Bond Polarity Electronegativity
Attraction an atom has for a shared pair of electrons.
higher e-neg atom  -
lower e-neg atom +

26. Bond Polarity Nonpolar Covalent Bond e- are shared equally
symmetrical e- density
usually identical atoms

27. + - Bond Polarity Polar Covalent Bond e- are shared unequally
asymmetrical e- density
results in partial charges (dipole) + -

28. View Bonding Animations.
Bond Polarity
Nonpolar
Polar
Ionic
View Bonding Animations.

29. Bond Polarity
Examples:
Cl2
HCl
NaCl

30. + - Dipole Moment H Cl Direction of the polar bond in a molecule.
Arrow points toward the more e-neg atom.
H Cl + -

32. Intermolecular vs. Intramolecular
Molecular Bonding involves forces BETWEEN molecules

33. H –FON dipoles

34. Dipole-dipole forces

35. Polar molecules are attracted to positively and negatively charged particles.

36. Ion - dipole forces: the reason for salts dissolving in water

37. Determining Molecular Polarity
Polar Molecules
Dipole moments are asymmetrical and don’t cancel .
H2O H O
net
dipole
moment

38. Determining Molecular Polarity
Nonpolar Molecules
Dipole moments are symmetrical and cancel out.
Bond Polarity
BF3 F B

39. London Forces

40. London Forces

41. Molecular Bonds Bonds Between molecules
Low melting points – weak bonds
Non-polar molecules have weaker bonds than polar
Polar dissolves polar
Non-polar dissolves non-polar
Polar bonds have brittle structures.

42. solubility of polar molecules

43. Covalent Network

44. Covalent Networks Very hard, Not brittle – not made up of ions
Crystal structure – creates a systematic pattern of atoms
High Melting point – strong covalent bonds

45. Metallic Bonding - “Electron Sea”
Types of Bonds
Metallic Bonding - “Electron Sea”
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46. Properties of Metallic Bonding
Shiny – electrons are constantly filling unfilled lower energy levels.
Conducts electricity – electrons are free to flow
Malleable, ductile - electrons are free to flow -no rigid planes of balanced charges.
High Melting points – strong bonds