covalent bonding

• What is a covalent bond?

  A strong bond formed by shared electrons
• What are simple molecular substances made of?

  Molecules containing a few atoms joined by covalent bonds
• How does an oxygen atom complete its outer shell in O₂?

  By forming a double covalent bond with another oxygen atom
• How many covalent bonds does water (H₂O) have?

  Two single covalent bonds
• What type of bonds are formed in carbon dioxide (CO₂)?

  Two double covalent bonds
• How many single covalent bonds can carbon form in methane (CH₄)?

  Four single covalent bonds
• What are the properties of simple molecular substances?

  1. Contain covalent bonds with simple structures
  2. Strong covalent bonds within molecules
  3. Weak intermolecular forces between molecules
  4. Low melting and boiling points
  5. Mostly gases or liquids at room temperature
  6. Don't conduct electricity
  7. Variable solubility in water
• Why do simple molecular compounds have low melting and boiling points?

  Because only weak intermolecular forces are broken
• What state are most molecular substances at room temperature?

  Gases or liquids
• How does the size of molecules affect intermolecular forces?

  Larger molecules have stronger intermolecular forces
• Why don't molecular compounds conduct electricity?

  They lack free electrons or ions
• What is the relationship between solubility in water and simple molecules?

  Some are soluble, some aren't
• What are polymers made of?

  • Long chains of covalently bonded carbon atoms
  • Formed from small molecules called monomers
  • Example: poly(ethene)
• What is the term for the small molecules that join to form polymers?

  Monomers
• What is the repeat unit in polymers?

  Monomers joined together
• What happens when a simple molecular substance melts?

  Weak intermolecular forces are broken
• Why is oxygen, O₂, a gas at room temperature?

  Weak intermolecular forces allow easy movement
• Why doesn't nitrogen, N₂, conduct electricity?

  It has no free electrons or ions