Chapter C2 - The Periodic Table

• How is the modern 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 located on the Periodic Table?

  Left
• Where are non-metals located on the Periodic Table?

  Right
• What name is given to the Group 1 elements?

  Alkali metals
• Why are the alkali metals names this?

  They are metals that react with water to form an alkali
• Give the general equation 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 metals change down the group?

  Increases (more reactive)
• Why does the reactivity of the alkali metals increase 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
• How do the melting points of the halogens change down the group?

  Increase (higher melting point)
• How does the reactivity of the halogens change down the group?

  Decrease (less reactive)
• What is a displacement reaction?

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

  Noble gases
• Why are the noble gases inert?


  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 point)
• What is an element?


  A substance which cannot be broken down into simpler substances
• How many types of atoms is an element made up of?


  1
• What is a substance?


  Anything that has mass and therefore can be weighed
• What are compounds?

  Pure substances - they are made up of 1 type of particle (typically molecules or oppositely charged ions)
• What is a molecule?

  A group of 2 or more atoms chemically bonded together (elements or compounds)
• What is an ion?


  An atom or molecule with electrostatic charge
• How many elements are in compounds ending IDE? (eg. lithium chlorIDE)

  2
• How many elements are in compounds ending ATE? (eg. lithium chlorate)

  3 (1 is always oxygen)
• Which 2 elements is hydroxide made up of?


  Hydrogen and oxygen
• What did Mendeleev make sure to do when making his periodic table?


  Leave gaps for unknown elements
• What does the group number determine in terms of electrons?

  The number of outer shell electrons