Unit 1 Chemistry

• How many electrons can an s subshell hold?

  2
• How many electrons can a p subshell hold?

  6
• How many electrons can a d subshell hold?

  10
• Which subshells are available in the first energy level?

  s
• Which subshells are available in the second energy level?


  s and p
• Which subshells are available in the third energy level?


  s, p and d
• What is Hund's rule?

  Orbitals must all be singly filled before they can be doubly occupied
• Which elements do not fill the 4s subshell before the 3d subshell?

  Copper and chromium
• Define the term ionic bond


  The electrostatic attraction between oppositely charged ions
• 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
• Explain how atoms of sodium react with atoms of chlorine

  Na loses its 2s1 electron gaining a +ve charge.

  Cl gains an electron in the 3p subshell gaining a -ve charge.

  The opposite charges attract to form NaCl
• Why do ionic bonds have such high melting points?

  Each +ve ion is surrounded by 6 -ve ions and vice versa.

  Strong electrostatic attraction in every direction.

  Requires a large amount of energy to break
• State two factors that affect the strength of an ionic bond

  Size of ion and charge on ion
• When can ionic substances conduct electricity?

  When molten or in aqueous solution
• Describe the properties of ionic compounds

  Conduct electricity when molten or aqueous solution

  High melting/boiling points

  Usually soluble in water
• Define the term covalent bond


  A shared pair of electrons
• Which metals lose electrons from the 4s subshell before the 3d subshell?

  Transition metals
• Why do metals have such high melting points?

  Strong force of attraction between positive ions and delocalised electrons. This requires a large amount of energy to overcome.
• State the two factors that affect the strength of metallic bonding

  Size of ion

  Charge on ion
• Explain how the charge on metal ions affects the strength of the metallic bond

  The larger the +ve charge the greater the attraction between the nucleus and the delocalised electrons
• Explain how the size of the metal ions affects the strength of the metallic bond

  The smaller the +ve ion the closer the nucleus is to the delocalised electrons creating a greater attraction
• Explain why metals conduct electricity

  The delocalised electrons 'carry' charge. Current flows because of this.
• Explain why metals conduct heat

  Particles are paced tightly so kinetic energy is passed from ion to ion. The delocalised electrons also enable heat to be passed.
• Explain why metals are ductile and malleable

  The lattice structure allows layers of metal ions to slide over each other without disrupting bonding
• Name the 3 forces between molecules

  Van der Waals

  Permanent dipole-dipole

  Hydrogen bonds
• Order the 3 forces between molecules in order of strongest to weakest

  Hydrogen bonds

  Permanent dipole-dipole

  Van der Waals
• How are Van der Waal's forces formed?

  Electrons move to one side, caused temporary dipole. This induces a temporary dipole in neighbouring molecules. Attraction occurs between oppositely charged dipoles
• In what molecules do Van der Waal's forces exist?

  Non-polar molecules
• How are permanent dipole-dipole forces formed?

  Permanent dipole in one molecule attracts oppositely charged permanent dipole in neighbouring molecule
• In which molecules do permanent dipole-dipole forces exist?

  Polar molecules
• Which elements must be present for hydrogen bonds to exist?

  Hydrogen and either nitrogen, oxygen or fluorine
• What is meant by the term displacement?

  When a more reactive element takes the place of a less reactive element in a compound
• State the equation for determining moles

  Moles = mass ÷ relative atomic mass (molar mass)
• Define the term Avogadro's Constant


  The number of atoms in a mole of a given substance. Quoted as 6.02x10^23
• Define the term relative atomic mass

  The average mass of an atom of an element relative to 1/12th the relative atomic mass of Carbon12
• Define the term relative molecular mass

  The average mass of a molecule relative to 1/12th the relative atomic mass of Carbon12
• What does this number represent? 6.02x10^23


  The number of particles in a mole. Commonly called Avogadro's Constant