Atomic Structure and the Periodic Table

• What is the difference between a compound and a mixture?

  A compound contains 2 or more elements which are chemically combined. A mixture contains 2 or more elements which are not chemically combined.
• What are the 2 different ways to sum up what has happened in a chemical reaction?

  . A word equation

  . A balanced symbol equation
• What is filtration used for?

  To separate soluble solids from insoluble solids e.g. separating salt from sand.
• What is crystallisation used for?

  To obtain a soluble solid from a solution e.g. obtaining salt crystals from salty water.
• What is simple distillation used for?

  To obtain a solvent from a solution.
• What is fractional distillation used for?

  To separate mixtures where the components have different boiling points e.g. obtaining oxygen and nitrogen from liquid air.
• What is chromatography used for?

  To separate the different soluble coloured components of a mixture e.g. colours in a fizzy drink
• What is a molecule?

  A particle that contains 2 or more atoms joined together.
• What is the plum pudding model of the atom?

  The plum pudding model suggested that atoms contained tiny, negative electrons surrounded by a sea of positive charge - Like a plum pudding.
• What is the nuclear model of the atom?

  The nuclear model of the atom suggested that the positive charge in an atom must be concentrated in a very small area - the nucleus.
• What is the atomic number of an atom?

  The number of protons
• What is the mass number of an atom?

  The number of protons and neutrons
• What is an Isotope ?

  Isotopes of an element have the same number of protons but a different number of neutrons.
• What are ions?

  Ions are formed when atoms gain or lose electrons.

  
  

  Lose ions = Positively Charged

  Gain ions = Negatively Charged
• Who designed the periodic table?

  Dimitri Mendeleev
• What are group 0 elements known as?

  The noble gases.

  Properties:

  .Full outer shell = Stable electron configuration = Very unreactive .Boiling points increase down the group
• What are group 1 elements known as?

  Alkali metals : They are very reactive, have low melting and boiling points and are stored under oils as they react with oxygen and water.
• What is the formula for group 1 elements that react with water?

  Alkali metals + water ---> metal hydroxide + hydrogen
• What does sodium + chlorine make?

  Sodium Chloride : Group 1 elements + non metals ---> ionic compounds
• What are group 7 elements known as?

  The halogens. They have 7 electrons in their outer shell and react with metals to form ionic salts.
• What are the transition metals?

  The elements in the centre of the periodic table, between group 2 and 3. They can be used as catalysts.
• What are the relative masses of protons, neutrons and electrons?

  Proton : 1

  Neutron : 1

  Electron : very small (close to 0)
• What are the relative charges of protons, neutrons and electrons?

  Proton : +1

  Neutron : 0

  Electron : -1
• What is the difference between a Solvent, a Solute and a Solution?

  A solvent can dissolve another substance. A solute is a substance that is dissolved by another substance. A solution is a mixture that occurs when a solvent dissolves a solute.