Chemical Bonding

Chemical bonds are an important part of what gives chemicals the properties they have. Bonds can occur within molecules and polyatomic ions or between atoms and molecules. Different types of bonds allow substances to have different melting points and boiling points, determine what they can mix with, and whether or not they conduct electricity. A specific type of bond that will be discussed in this unit (hydrogen bonds) is responsible for water expanding when it freezes and the two strands of a DNA molecule being held together. There is energy stored within chemical bonds. Depending upon the types of bonds that are broken and formed during a chemical or physical change determines how much energy is absorbed or released during the change of matter.

Part 1: What are they?

Using the reference materials available describe a chemical bond. Make sure within your description you state what part or parts of an atom are involved in forming chemical bonds. Also illustrate a chemical bond within a compound.

Part 2: Time to make the transfer.

  1. Take a small amount to table salt, NaCl, add it to a 250 mL beaker half full with water and stir. Then test the conductivity of the salt water mixture. Record your observations and list what type of compound is sodium chloride.
  2. Test the conductivity of solid sodium chloride and record your observations.
  3. Put a small amount of table salt in a small test tube and put the test tube in near boiling water for two minutes. Record your observations.
  4. Sodium chloride contains ionic bonds that hold the atoms together. For ionic bonds describe the following information in a paragraph type format using complete sentences.

a)What is happening with electrons to form ionic bonds?

b)What type of elements generally combine together to form ionic bonds?

c)Describe the conductivity of compounds containing ionic bonds.

d)Describe the melting point of compounds containing ionic bonds.

  1. Draw a diagram, using dot diagrams, showing what is happening with electrons when an ionic bond is formed.

Part 3: Why not share instead of fight over them.

  1. Repeat the steps 1 and 2 from part 2 using sugar, C12H22O11, instead of table salt.
  2. Put a small amount of cetyl alcohol in a small test tube and put the test tube in near boiling water for one minute. Record your observations.
  3. Sugar and cetyl alcohol, CH3(CH2)14CH2OH, contain covalent bonds that hold the atoms together. For covalent bonds describe the following information in a paragraph type format using complete sentences.

a)What is happening with electrons to form covalent bonds?

b)What type of elements generally combine together to form covalent bonds?

c)Describe the conductivity of compounds containing covalent bonds.

d)Describe the melting point of compounds containing covalent bonds.

e)Draw a diagram, using dot diagrams, showing what is happening with electrons when a covalent bond is formed.

Part 3: We’re on our own.

Describe the characteristics of metallic bonds in terms of how they are formed, what is happening with electrons, conductivity, and melting point.