Atoms and the Periodic Table

• Define Atom


  The smallest part of an element that can still be recognised as that element
• Define element 


  A substance made of only one type of atom
• Define compound


  A substance made of two or more different atoms chemically bonded together
• Define molecule 


  A substance made of more than one atom chemically bonded together (can be atoms of the same type!)
• Define mixture


  A substance made of more than one thing not chemically bonded together
• 3 Subatomic particles are...

  Protons

  Neutrons

  Electrons
• State the masses of the subatomic particles


  Protons: +1

  Neutrons: +1

  Electrons: 0
• State the relative charges of the subatomic particles


  Protons: +1

  Neutrons: 0

  Electrons: -1
• How are the subatomic particles arranged in an atom?

  Protons and neutrons in the nucleus, electrons orbiting in shells
• What is the plum pudding model of the atom?

  A ball of positive charge with negative electrons studded into it
• What did the gold foil experiment prove?

  That atoms have dense nucleuses with a positive charge
• What is the atomic number of an atom?

  Number of protons in an atom
• What is the mass number of an atom?

  The number of protons + the number of neutrons in an atom
• How do you calculate the number of neutrons in an atom?

  Mass number - atomic number
• How are the electrons arranged in atoms?

  Orbiting the nucleus in shells
• How many electrons can go in the first shell?

  2
• How many electrons can go in the second and third shells?

  8
• What does the Law of conservation of mass state?


  That during a chemical reaction no new atoms are ever created or destroyed: mass of reactants = mass of products
• Why might it appear that a reacting system has lost or gained mass?

  If a reactant or product is a gas it will appear to lose or gain mass
• What is a mixture?

  A mixture is made up of two substances that are not chemically combined together
• What processes can be used to separate mixtures?

  Filtration(insoluble solids from liquids), crystallisation (soluble solids from liquids); distillation (soluble solids from liquids but collecting the liquid)
• What is fractional distillation?

  A process used to separate miscible liquids using their different boiling points
• What is paper chromatography?

  A process used to separate a mixture of substances dissolved in a solvent
• What is an ion?


  An atom that has lost or gained electrons to become charged
• What is an isotope?

  Isotopes are atoms of the same element that has the same number of protons and electrons but a different number of neutrons