Paper 1 wrong answers

• Why does first ionisation energy increase across a period?

  increased nuclear charge

  atomic radius decreases

  electrons added to the same shell/same shielding
• Equation for the second ionisation energy of oxygen?

  O+ - O2+ + e-
• Why is successive ionisation energy larger?

  proton electron ratio increases

  electron repulsion/ shielding smaller

  o+ ion smaller than o atom
• Why do boiling points of halogens increase down the group?

  -more induced dipole forces

  -no of electrons increases

  -more energy needed to break intermolecular forces
• What colour change would you see when chlorine displaces iodine?


  solution turns brown
• What is meant by one mole of a substance ?

  amount of substance which contains as many particles as there are carbon atoms in 12g of carbon 12
• How do Van der Waals forces arise?

  uneven distribution of electrons

  creates an instantaneous dipole

  causes induced dipole in neighbouring molecules
• Why is astatine expected to behave similarly to other halogens?

  same number of electrons in outer shell
• Explain reactivity down group 7?

  reactivity decreases down the group

  chlorine most reactive / gains negative ion easiest

  because chlorine atom is smallest/ has least shielding/nuclear attraction is greatest
• Reaction of fluorine with water?

  2F2 + 2H2o > 4HF + O2
• What is an equivalence point?


  the point in a titration at which the volume of one solution has reacted exactly with the volume of the second solution.
• How has X become a salt ?

  .the hydrogen ion of an acid has been replaced by metal ion
• Empirical formula

  simplest whole number ratio of atoms of each element present in a compound
• Why is molecule polar?

  dipoles do not cancel

  because molecule is non symmetrical