C2 Questions

• How is the periodic table ordered?


  By atomic number.
• How were the early lists of elements ordered?


  By atomic mass.
• Why did Mendeleev swap the order of some elements?


  To group them by their chemical properties.
• Why did Mendeleev leave gaps in his periodic table?


  Leave room for elements that had not yet been discovered.
• Why do elements in a group have similar chemical properties?


  Have the same number of electrons in their outer shell.
• Where are metals and non-metals located on the periodic table?


  Metals to the left, non-metals to the right.
• What name is given to the group 1 elements?

  Alkali metals.
• Why are the alkali metals named this?

  They are metals that react with water to form an alkali.
• Give the general equations for the reactions of alkali metals with oxygen, chlorine, and water.


  metal + oxygen --> metal oxide

  metal + chlorine --> metal chloride

  metal + water --> metal hydroxide + hydrogen
• How does the reactivity of the alkali change down the group?

  increases (more reactive)
• Why does the reactivity of the alkali metals increase as you go down the group?

  They are larger atoms, so the outermost electron is further from the nucleus, meaning there are weaker electrostatic forces of attraction and more shielding between the nucleus and outer electron, and it is easier to lose the electron.
• What name is given to the Group 7 elements?

  halogens
• Give the formulae to the first four halogens.

  F2 , Cl2 , Br2 , I2
• How do the melting points of the halogens change down the group?


  increase (higher melting points)
• How does the reactivity of the halogens change down the group?


  decreases (less reactive)
• Why does the reactivity of the halogens decrease down the group?

  They are larger atoms, so the outermost shell is further from the nucleus, meaning there are weaker electrostatic forces of attraction and more shielding between the nucleus and outer shell, and it is harder to gain an electron.
• What is a displacement reaction?

  When a more reactive element takes the place of a less reactive one in a compound.
• What is given to the Group 0 elements?

  noble gases
• Why are the noble gases inert (chemically inactive)?

  They have full outer shells so do not need to lose or gain electrons.
• How do the melting points of the noble gases change down the group?

  increase (higher melting points)
• product

  a substance made as a result of a chemical reaction.
• isotope

  atoms that have the same number of protons but different number of neutrons.