covalent

• What is covalent bonding?

  The sharing of a pair of electrons between non-metal atoms, to achieve a full outer shell.
• How is a hydrogen molecule (H₂) formed?

  They share one pair of electrons forming a covalent bond, they both achieve a full outer shell making the molecule stable.
• What is a double covalent bond?

  The sharing of 2 pairs of electrons. For example, oxygen
• What are some properties of covalent compounds?

  Low melting and boiling points, and don't conduct electricity.
• Why do covalent compounds generally have low melting points?

  Because of their weak intermolecular forces, requiring little energy to break
• What is the formula for a hydrogen molecule?

  $H_2$
• Why do hydrogen atoms bond together in a hydrogen molecule?

  To achieve a full outer shell by sharing electrons
• What type of bond is formed when two (g) atoms share electrons?

  Covalent bond
• What is the formula for hydrogen chloride?

  $HCl$
• What type of bond do non-metals typically form to join together?

  Covalent bonds
• What are giant covalent structures?

  Giant covalent structures are formed by non-metals bonding covalently to create large, repeating networks of atoms.
• Why do simple molecular substances melt or boil at low temperatures?

  They only need to break weak intermolecular forces between different molecules.
• How do intermolecular forces affect the melting and boiling points of simple molecular substances?

  • More intermolecular forces increase attraction between molecules.
  • Stronger attraction requires more energy to melt or boil.
  • Boiling and melting points increase with more intermolecular forces.
• Why don't simple molecular substances conduct electricity?

  They don't conduct electricity because there are no free electrons and the molecules themselves have no electric charge.
• What are giant covalent structures?

  • Large networks of non-metal atoms
  • Held together by covalent bonds
  • Arranged into regular repeating lattices
  • Examples: diamond, graphite, silicon dioxide
• Why don't most giant covalent structures conduct electricity?

  They generally don't conduct electricity because they don't contain any charged particles, even when molten.
• What are the main properties of giant covalent structures?

  They are very strong and have high melting and boiling points because all covalent bonds must be broken to melt or boil them.
• Which giant covalent structures are exceptions to the general non-conductivity?

  • Graphite
  • Diamond
• What types of elements form covalent bonds?

  Non-metal elements
• How does covalent bonding differ from ionic bonding?

  Covalent - sharing of electrons

  Ionic - transfer of electrons
• Give an example of a molecule with a double covalent bond.

  Oxygen
• Give an example of a molecule with a single covalent bond.

  Hydrogen
• Give an example of a molecule with a triple covalent bond.

  Nitrogen
• Do covalent compounds conduct electricity?

  No, because they don't have free-moving charged particles (no ions or delocalised electrons).
• Why are most covalent compounds gases or liquids at room temperature?

  Their weak intermolecular forces make them volatile
• Describe the bonding in a water molecule.

  Two single covalent bonds between oxygen and both hydrogen atoms
• Describe the bonding in carbon dioxide.

  Two double covalent bonds between carbon and both oxygen atoms
• Why does graphite conduct electricity?

  It has delocalized electrons that can move through the structure.