C3

• What are the three types of chemical bonds?

  Ionic

  Covalent

  Metallic
• What is a covalent bond?


  Sharing of electrons between two non-metals.
• What is a metallic bond?


  A metallic bond is the electrostatic attraction between positively charged metal ions and delocalised electrons.

  Occurs only in metal atoms.
• How does an ionic compound form?

  Occurring between Metal and Non-Metals, The metal loses electron(s) to become a positively charged ion while non-metal gains electron(s) to become a negatively charged ion.

  The oppositely charged ions are electrostatically attracted to each other
• What is the charge of an ion from group 1?

  +1
• What is the charge of an ion from group 2?

  +2
• What is the charge of an ion from group 6?

  -2
• What is the charge of an ion from group 7?

  -1
• What is an ionic compound?


  A giant structure of ions which are held together by strong electrostatic forces of attraction between oppositely charged ions
• What are simple molecules?

  Small molecules such as oxygen and water that contain atoms joined together by covalent bonds.
• What is the state symbol for a solid?


  (s)
• What is the state symbol of a liquid?

  (l)
• What is the state symbol of a gas?

  (g)
• What is the state symbol for a solution?

  (aq)
• Properties of ionic compounds?

  High melting and boiling point

  Conduct electricity when molten or dissolved
• Why do ionic compounds have high melting and boiling points?

  Strong bonds between molecules which takes lots of energy to overcome.
• Why can't ionic compounds conduct electricity when solid?

  Ions are unable to move freely
• Why can ionic compounds conduct electricity when molten/dissolved?

  Ions are free so they are able to move
• What are the properties of simple molecules?

  Low melting and boiling points

  Poor conductors
• Why do simple molecules have low melting and boiling points

  Weak bonds between the molecules, therefore little energy is needed to overcome these bonds.
• Examples of giant covalent structures?

  Diamond and graphite
• What is the structure of diamond?

  Each carbon atom is covalently bonded to 4 others in a giant structure
• What is the structure of graphite?

  Each Carbon atom is covalently bonded to 3 others in a giant structure.
• Why can graphite conduct electricity?

  It has free electrons which are able to move
• Why does diamond and graphite have high melting and boiling points?

  Strong covalent bonds between atoms which take lots of energy to overcome
• What is graphene?


  A single layer of graphite
• What are properties of graphene?


  Conducts electricity and is strong
• What are fullerenes?


  Molecules of carbon atoms with hollow shapes
• What does the law of conservation of mass state?

  No atoms are lost or made during a chemical reaction, so the mass of the products equals the mass of the reactants.
• Write the balanced equation for magnesium reacting with hydrochloric acid.

  Mg(s) + 2 HCl(aq) → MgCl2(aq) + H2(g)
• Define relative atomic mass (RAM).

  RAM is the average mass of atoms in an element, taking into account the masses and abundance of its isotopes, relative to 12C.
• Define relative formula mass (RFM).

  RFM is the sum of the relative atomic masses of all atoms in the formula.
• What is the relative formula mass of CaF2?

  78 (Ca = 40, F = 19, so 40 + 19 + 19 = 78)
• What is the relative formula mass of C6H12O6?

  180 (C = 12, H = 1, O = 16; (12 x 6) + (1 x 12) + (16 x 6) = 180)
• Why do carbon dioxide and water escape from the test tube in the reaction of magnesium oxide and methane?

  • They are both gases.
  • Gases can escape easily from the test tube.
• Calculate the mean mass of magnesium produced from the experiment.

  The mean mass is $(3.3 + 3.5 + 3.2) / 3 =$$3.3 \text{ g}$.
• How can you increase the precision of the results in the magnesium experiment?

  Measure to more decimal places or use a more sensitive balance/apparatus.
• What is Avogadro's constant?

  It is the number of atoms, molecules, or ions in a mole of a substance, valued at $6.02 \times 10^{23}$.
• What is the formula that links mass, molecular mass, and moles?

  Mass = Mr x Moles
• What is the mass of 20 moles of calcium carbonate, CaCO3?

  The mass is $100 \times 20 =$$2000 \text{ g}$.