C3

• What is the purpose of a heating or cooling curve?

  To track changes in the state of a substance by measuring its temperature over time.
• What pattern is observed in a heating curve?

  A quick increase in temperature followed by flattening out, then another increase and flattening out.
• Why do flattening points occur in a heating curve?


  They indicate a change in state, such as melting or evaporating.
• What happens to a solid during the melting process?

  It changes into a liquid.
• Why does evaporating require more energy than melting?

  Because particles must separate completely to form a gas, while in a liquid they are still touching.
• What is a limitation of the particle model discussed in the material?

  Not all particles are perfect spheres, and their size can vary.
• Why do atoms seek to have a full outer shell of electrons?

  Atoms are more stable when they have a full outer shell, typically eight electrons.
• What charge does aluminium have after losing three electrons?


  It has a charge of +3.
• How can you determine the charge of an atom from the periodic table?

  By knowing the group number: Group 1 has +1, Group 2 has +2, Group 3 has +3, and so on.
• What is the charge of chlorine after gaining one electron?

  It has a charge of -1.
• Why is ionic bonding important?

  It results from atoms becoming ions and involves the transfer of electrons between atoms.
• How do you represent the transfer of electrons in ionic bonding?

  Using dots and crosses to show where the electrons have gone.
• What is the molecular formula for lithium oxide?

  Li₂O
• What is a lattice in the context of ionic compounds?

  A regular repeating unit structure formed by ionic compounds.
• What is a key characteristic of ionic compounds regarding their melting and boiling points?

  They often have high melting and boiling points.
• Why do ionic compounds conduct electricity when molten or dissolved?

  Because the ions are free to move in a liquid state.
• How does the charge on ions affect the boiling points of ionic compounds?

  Higher charges lead to stronger electrostatic forces, resulting in higher boiling points.
• What is covalent bonding?

  Covalent bonding occurs when two non-metals share electrons.
• How is the electron configuration of hydrogen fluoride represented using the dot and cross method?

  Hydrogen has one electron and fluorine has seven, sharing one electron to achieve full outer shells.
• What happens to the electron configuration of hydrogen when it bonds with fluorine?

  Hydrogen achieves a full outer shell with two electrons.
• How many electrons does chlorine have in its outer shell after bonding with hydrogen?


  Chlorine has eight electrons in its outer shell after sharing.
• What are the key differences between ionic and covalent bonding?

  • Ionic bonding involves transfer of electrons between metals and non-metals.
  • Covalent bonding involves sharing of electrons between non-metals.
  • Ionic bonds form ions with charges, while covalent bonds do not.
• What are the properties of ionic compounds?

  • High melting and boiling points due to strong electrostatic forces.
  • Conduct electricity when molten or dissolved in solution.
  • Form giant lattices with regular repeating units.
• How do you determine the molecular formula of an ionic compound?

  1. Identify the charges of the ions.
  2. Use the diagonal rule to find the ratio of ions.
  3. Write the formula based on the ratio.
• How many electrons does chlorine have in its outer shell?

  Seven electrons
• How can you determine the number of electrons in chlorine's outer shell?

  By referring to the periodic table, as chlorine is in group seven
• What happens to hydrogen's outer shell when it forms a bond with chlorine?

  Hydrogen achieves a full outer shell with two electrons
• How many electrons does chlorine have in its outer shell after bonding with hydrogen?

  Eight electrons
• What is the process of forming a covalent bond between hydrogen and chlorine?

  • Hydrogen shares one electron with chlorine
  • Chlorine shares one electron with hydrogen
  • Both achieve full outer shells
• What is the chemical formula for silicon tetrafluoride?

  SiF$_4$
• How can you determine if silicon tetrafluoride is a covalent compound?

  By checking that both silicon and fluorine are nonmetals
• What is the first step in drawing the dot and cross diagrams for silicon and fluorine?

  Draw silicon with crosses and fluorine with dots
• How many bonding pairs does silicon need to achieve a full outer shell?

  Four bonding pairs
• How many electrons does each fluorine atom need to achieve a full outer shell?

  One electron
• What are the characteristics of simple covalent compounds compared to ionic compounds?


  • Do not form giant lattices
  • Have weak or no forces of attraction between molecules
  • Low melting and boiling points
  • Do not conduct electricity
• What is the key property of graphite that allows it to conduct electricity?

  It contains delocalized electrons
• Why is graphite considered a good lubricant?

  Because its layers can slide over one another due to weak intermolecular forces
• How many bonds does each carbon atom form in diamond?

  Four bonds
• Why does diamond not conduct electricity?


  Because it has no delocalized electrons
• What is the formula for buckminsterfullerene?

  C$_{60}$