1. A bond is when 2 or more atoms combine to:
Chemical Bonding
A bond is when 2 or more atoms combine to:
Lower their energy
Become more stable

2. Covalent Bonds
A covalent bond is a bond in which the atoms share electrons in an overlapping manner.
They are formed between two non-metals.
There are two types of covalent bonds: polar and non-polar.

3. Non-polar Covalent Bonds
A non-polar covalent bond is a covalent bond in which the bonding electrons are shared equally by the bonded atoms, resulting in a balanced distribution of electrical charge.

4. Non-polar Covalent Bonds
Examples of non-polar covalent bonds are the diatomic elements. (the “gen” series)
H2, N2, O2, F2, Cl2, Br2, I2 Cl

5. Polar Covalent Bonds
A polar covalent bond is a covalent bond in which the bonded atoms have an unequal attraction for the shared electrons. Cl H

6. Covalent Bonds
One way to tell the difference between a polar and non-polar covalent bond is by the electronegativities. If the electronegativities are equal the compound is non-polar. If the electronegativities are not equal the compound is polar.

7. Covalent Bonds
Another way to tell a difference between a polar and non-polar molecule is if a molecule is symmetrical, its non-polar and if it isn’t, it is polar.
Water is a polar molecule. O H

8. Covalent Bonds
Molecules can be held together by single, double, or even triple covalent bonds.
In a single bond the atoms share 2 electrons.
In a double bond the atoms share 4 electrons.
In a triple bond the atoms share 6 electrons. N O H

9. Ionic Bonding
An ionic compound is composed of a positive and a negative ions that are combined so that the number of positive and negative charges are equal.
Ionic bonds are formed usually formed between metals and non-metals.

10. Ionic Bonding
Example: NaCl -1 Cl Na +1

11. Bonding
One way to tell if a compound is covalent or ionic is by the electronegativities of the atoms. If you subtract the electronegativities of both atoms and you come out with 0.0 – 1.7, it is a covalent bond. If you come out with , it is a ionic bond.

12. Bonding Example: HCl: H has a electronegativity of 2.5
Cl has a electronegativity of 3.2
Therefore it is a polar covalent molecule.

13. Polyatomic Ions
A polyatomic ion is a compound of two or more covalently bonded atoms with a charge.
These ions are found on reference table E.
Examples:
OH-, NH4+,

14. VSEPR Theory Valence Shell Electron Pair Repulsion Molecule Type
Example
Shape
AB2
BeF2
Linear
AB3
BF3
Trigonal planar
AB4
CH4
Tetrahedral
AB3E
NH3
Trigonal pyramid
AB2E
SnCl2
Bent
AB2E2
H2O

15. Metallic Bonding
Metallic bonding is the chemical bonding that results from the attraction between metal atoms and the surrounding sea of electrons.
Fe+ e-

16. Intermolecular Forces of Attraction
Intermolecular forces are the forces of attraction between molecules.

17. Dipole-Dipole Forces
The forces of attraction between polar molecules are known as dipole-dipole forces.

18. Hydrogen Bonding
Hydrogen bonding is a very strong dipole-dipole attraction that only occurs between hydrogens and small electronegative atoms such as nitrogen, oxygen, and fluorine.
One example is water.

19. Van der Waal Forces
Van der Waal forces are forces that hold non-polar molecules together.
Some examples are the diatomic elements.

20. Network Solids
A network solid is an strong on going link of non-polar covalent bonds.
Examples:
Diamonds
Silicon
Sand (SiO2)
SiC (used for computer chips)

21. Bonds and forces are listed from the weakest to the strongest.
Forces of Attraction
Non-polar
Van der Waals
Polar
Dipole-Dipole
Ionic
Hydrogen Bonding
Metallic
Ionic Solids
Network Solids
Bonds and forces are listed from the weakest to the strongest.

22. Chemical Bonding Review Questions

23. Which bond has the greatest degree of ionic character?
a) I-Cl
b) Cl-Cl
c) H-Cl
d) K-Cl
Answer: D

24. 2) Which compound contains ionic bonds?
a) HBr
b) NaBr
c) C6H12O6
d) CO2
Answer: B

25. 3) A characteristic of ionic solids is that they:
a) Have low boiling points
b) Are noncrystalline
c) Conduct electricity
d) Have high melting points
Answer: D

26. 4) Which substance will conduct electricity in both the solid phase and the liquid phase?
a) H2
b) Ag
c) HCl
d) AgCl
Answer: B

27. Answer: B a) A molecular solid b) An ionic solid c) A network solid
5) A substance that has a melting point of 1074 K conducts electricity when dissolved in water, but does not conduct electricity in a solid phase. The substance is most likely:
a) A molecular solid
b) An ionic solid
c) A network solid
d) A metallic solid
Answer: B

28. 6) A molecule of ammonia (NH3) contains:
a) Covalent bonds, only
b) Both covalent and ionic bonds
c) Neither covalent and ionic bonds
d) Ionic bonds, only
Answer: A

29. 7) The correct electron dot formula for hydrogen chloride is:
a) H Cl
b) H Cl
c) H Cl
d) H Cl
Answer: C

30. 8) Which formula represents a tetrahedral molecule?
a) CaCl2
b) Br2
c) CH4
d) HBr
Answer: C

31. 9) Two atoms of element A unite to form a molecule with the formula A2. The bond between the atoms in the molecule is:
a) Polar covalent
b) Non-polar covalent
c) Electrovalent
d) Ionic
Answer: B

32. 10) What type of bonding is found in the molecule HBr?
a) Non-polar covalent
b) Polar covalent
c) Ionic
d) Metallic
Answer: B

33. 11) Which type of bond is contained in a water molecule?
a) Polar covalent
b) Electrovalent
c) Ionic
d) Non-polar covalent
Answer: A

34. 12) Which molecule is a dipole?
a) HCl
b) CH4
c) H2
d) N2
Answer: A

35. 13) Which structural formula represents a non-polar symmetrical molecule?b) c) d) O H C H H F H N
Answer: B

36. 14) The strongest hydrogen bonds are formed between molecules of:
a) H2Te
b) H2S
c) H2O
d) H2Se
Answer: C

37. 15) Which kind of bonds are found in a sample of H2O?
a) Both covalent and hydrogen bonds
b) Both ionic and hydrogen bonds
c) Hydrogen bonds, only
d) Covalent bonds, only
Answer: A

38. 16) Which of the following noble gases has the lowest normal boiling point?
a) Kr
b) Ne
c) Xe
d) Ar
Answer: B

39. 17) Which type of bonding accounts for the unusually high boiling point of water?
a) Network bonding
b) Covalent bonding
c) Van der Waals forces
d) Hydrogen bonding
Answer: D

40. 18) The attraction which exists between carbon dioxide molecules in solid carbon dioxide is due to
a) Ionic bonds
b) Hydrogen bonds
c) Van der Waals forces
d) Molecule-ion forces
Answer: C

41. 19) Helium may be liquefied at low temperature and high pressure primarily because of
a) Van der Waals forces
b) Hydrogen bonding
c) Covalent bonds
d) Ionic attraction
Answer: A

42. 20) Van der Waals forces of attraction between molecules decrease with
a) Decreasing # of electrons and increasing distance between the molecules
b) Increasing # of electrons and decreasing distance between the molecules
c) Decreasing # of electrons and decreasing distance between the molecules
d) Increasing # of electrons and increasing distance between the molecules
Answer: A

43. 21) Molecule-ion attractions are found in:
a) KBr (s)
b) CO (g)
c) NaCl (aq)
d) Cu (s)
Answer: C

44. 22) Which formula represents a molecular solid?
a) NaCl
b) Cu
c) C6H12O6
d) KF
Answer: C

45. 23) Which compound is a poor conductor of heat and electricity and has a high melting point?
a) H2O
b) CO2
c) SiO2
d) N2O
Answer: C

46. 24) What type of bonds are present in a strip of magnesium ribbon?
a) Van der Waals
b) Metallic
c) Ionic
d) Covalent
Answer: B

47. 25) Which substance contains positive ions immersed in a sea of mobile electrons?
a) CuO
b) SiO2
c) Cu
d) O2
Answer: C

48. Good Luck on your Test