Atomic structure (chemistry)

• What is an atom 


  The smallest part of an element that can exist
• What is an element 


  Made of one type of atom
• What Is a compound

  2 or more different elements chemically joined
• What are two things that always happen during chemical reactions

  1. The formation of 1 or more substances
  2. a detectable energy change
• What is a mixture

  A substance made of more than one element not chemically joined
• How are compounds formed

  They are former firm elements during chemical reactions
• What is filtrating 


  A separating technique that involves putting a mixture of an insoluble solid + liquid through a filter paper the solid collects on the filter paper and the liquid filtrate passes through the paper
• What type of mixtures does filtration separate

  Insoluble solids and liquids
• What is crystallisation 


  A separating technique that involves evaporating the liquids from a solution to be left with solid crystals
• What type of mixture does crystallisation separate

  Soluble solids and liquids
• What is simple distillation

  A separating technique that involves boiling liquid (solvent) to remove it from a mixture (solution) and then condensing to separate
• What type of mixture does simple distillation separate

  Soluble solids and liquids
• what is fractional distillation

  A separating technique that separates different liquids (with different boiling points) from a mixture of liquids. 
• What type of mixture does fractional distillation separate

  Mixture of liquids
• What is chromatography


  A separating technique that separates a mixture of soluble substances due to the fact that different sized molecules will travel at different speeds up the chromatography paper. 
• What type of mixture does chromatography separate

  Mixture of soluble substances
• What has led to a change in ideas about the structure of the atom? 


  New experimental evidence
• What did John Dalton suggest about the structure of the atom

  That atoms were tiny spheres that were indivisible. Each different element had a different size sphere  
• The discovery of what led to the plum pudding model of the atom? 

  Electrons
• What is the plum pudding model of the atom

  The atom is a ball of positive charge with negative electrons randomly scattered through it  
• What was the alpha particle scattering experiment

  Positively charged alpha particles were fired at gold foil. Some of the particles were repelled backwards by the positively charge nucleus of the gold atoms 
• Why did the new evidence from the scattering experiment lead to a change in the atomic model? 

  Because some of the alpha particles were repelled backwards by the concentrated positive centre, Rutherford suggested that the positive charge was contained in a nucleus and the negative electrons were in fixed positions around the outside 
• What is the nuclear model of the atom? 

  Positive charge in the nucleus of an atom, negative electrons in fixed positions around the outside of the atom, most of the atom is empty space
• What is the difference between the plum pudding model of the atom and the nuclear model of the atom? 

  In the plum pudding model the electrons are randomly scattered throughout whereas the in nuclear model they are in fixed positions around the outside. In the plum pudding model the sphere is a ball of positive charge, in the nuclear model the positive charge is enclosed in a nucleus in the centre of the atom. 
• How did Niels Bohr adapt the nuclear model? 

  He suggested that electrons were in fixed positions on energy shells rather than on fixed positions around the edge of the atom.
• What did the work of James Chadwick provide evidence for? 

  The neutron
• What is the relative charge of a proton? 

  +1
• What is the relative charge of a neutron

  0
• What is the relative charge of an electron

  -1
• In an atom, is the number of electrons the same as, more than, or less than, the number of protons

  the same as
• What does the atomic number of an atom tell us? 

  the number of protons
• What is the approximate radius of an atom

  0.1nm
• Where does almost all of the mass of an atom come from?

  The nucleus
• What is the relative mass of a proton

  1
• What is the relative mass of a neutron

  1
• What is the relative mass of an electron


  very small
• What is a does the mass number tell us about an atom?

  The number of protons and neutrons added together 
• How can we work out the number of neutrons an atom has using the mass and atomic numbers? 

  By subtracting the atomic number from the mass number 
• What is an isotope? 


  A form of an element with a different number of neutrons
• What is the maximum number of electrons that can occupy the first electron shell? 

  2