Natural Science Grade 7

• What is the periodic table?

  A list of elements which make up all the matter and materials in our world.
• How are the elements on the periodic table organised?

  according to the elements atomic number.
• Explain what an atomic number is?

  the number of protons in the atom of an element
• Who put together the periodic table?

  Dimitri Mendeleev
• Dimitri Mendeleev was a Russian chemist.
• The rows that go horizontal on the periodic table are called Periods
• The rows that go vertical are called Groups
• The elements are arranged into three main categories. What are they?

  Metals

  Non-metals

  Semi-metals
• Metals are arranged on the left hand side
• Non-metals are arranged on the right hand side
• Semi-metals are inbetween and in a zigzag pattern
• The periodic table shows.....of the elements? (5)

  Atomic number

  Electrons per shell

  Symbol

  Name

  Atomic mass
• How many elements on the periodic table are gases?

  11 elements
• Only two of the elements are liquids at room temperature. Which two elements are they?

  Mercury (Hg)

  Bromine(br)
• Qualities of Metals....There are 11. Name at least 6?

  Solid at room temperature (except mercury)

  High melting point

  high boiling point

  good conductor of heat

  good conductor of electricity

  ductile

  malleable

  shiny

  hard and strong

  Some are magnetic

  Some make good mixtures
• What metals are magnetic?

  The ones that have iron in them.
• Qualities of semi-metals? (4)

  solids

  semi conductors

  Brittle

  Look metallic
• Six of the eleven gases are noble gases
• What are noble gases?

  Gases that do not combine with other elements
• What colour is Carbon?

  black
• What colour is Sulfur?

  yellow
• What colour is phosphorus?

  White to red
• Where can you find Carbon?

  burnt toast

  plastic

  fuel
• Where can you find Sulfur?

  gunpowder

  match heads
• Where can you find Phosphorus?

  When there is alot of phosphorus in the sea, the water lights up when you stomp on it.
• What do Noble gases do when electricity passes through them?

  They produce a coloured light. Each one has its own colour. THe most well known one is neon
• When do Semi metals conduct electricity?

  When they are heated up
• The very tip of your tongue tastes sweet
• The sides next to the tip taste salty
• the sides up top taste sour
• the middle part right at the back tastes bitter
• The properties of acids are?

  Taste sour

  Feel rough on the skin

  Many are dangerous to taste or feel because they are corrosive
• Why does it hurt when an ant bites or a bee stings?

  The insect gives you a little injection of acid which burns
• What are the properties of bases?

  Taste bitter

  They feel slippery or soapy on the skin

  Many are dangerous to taste or feel because they are corrosive
• Many bases dissolve in water. The ones that are soluble in water are called alkalis
• How would you describe a neutral substance?

  Neutrals are neither bases nor acids
• How can you tell the difference between acids and bases?

  using an indicator
• What is an indicator?

  a substance that changes colour when it is added to an acid or a base
• What is litmus paper?

  A red-blue acid-base indicator
• blue litmus paper turns red in an acid. Red litmus paper turns blue in a base