chemistry paper 1

• What did dalton state atoms were?

  solid spheres
• what was the plum pudding model?

  atoms were a ball of positive cloud with electrons embedded in it
• what did the alpha scattering experiment conclude about atoms?

  atoms have a tiny positive nucleus at centre where mass is concentrated
• what did bohr state about atoms?

  electrons are contained in shells and they orbit the nucleus in fixed shells at specific distances
• what was the problem with placing elements in increasing atomic weight?

  elements were grouped together with diff properties
• what are some properties of transition metals?

  can form more then one ion, often coloured and good catalysts
• as we go down group 1, what are the properties?

  increasing reactivity, lower melting and boiling points, higher relative atomic masses
• what do group 1 metals form when reacted with water?

  hydrogen gas and metal hydroxide
• what do group 1 metals form when reacted with chlorine?

  white metal chloride salts
• what are some properties of the noble gases?

  non flammable, colourless gases at room temp and monatomic
• what are limitations to the particle theory?

  assumes all particles are solid spheres when they are different shapes and fails to consider intermolecular forces
• why od small covalent molecules not conduct electricity?

  they dont have overall electric charge
• what are properties of diamond?

  high melting and boiling point, does not conduct electricity and extremely hard
• why is diamond hard?

  contains many carbon atoms joined together by covalent bonds
• what are the properties of graphite?

  soft and slippery, good conductors of heat and electricity and high melting and boiling point
• why is graphite soft and slippery?

  it has no covalent bonds between layers and so they can slide over each other
• what is graphene?

  a single layer of graphite arranged in hexagonal rings and one atom thick
• why can metals be bent and shaped?

  layers of atoms can slide over each other
• how are alloys harder then metals?

  different sizes of atoms distort layers and so its difficult for layers to slide over each other
• why are nanoparticles advantageous?

  they have a huge surface area to volume ratio which means small amount of nanoparticles have a massive surface area and so a much smaller quantity of nanoparticles is needed
• what are the risks to nanoparticles?

  they are absorbed into the skin and can enter cells, no one knows the long term effects and so should be studied and used carefully
• what is an acid?

  a substance that forms an aqueous solution with a pH of less than 7
• what ions do acids form in water?

  H+
• what is a base?

  any subtance that reacts with an acid to form a salt
• what ions do alkali form in water?

  OH-
• what does acid and base produce (neutralisation)?

  salt and water
• what does an acid and a metal produce?

  salt and hydrogen
• what does metal and water produce?

  metal hydroxide and hydrogen
• what is an ore?

  a rock that contain metals in sufficient amounts to make it economically worth extracting
• what are native metals?

  ore that exists in nature in its actual metallic form
• what is oxidation in terms of oxygen?

  gain of oxygen
• what is reduction in terms of oxygen?

  loss of oxygen
• what is a strong acid?

  an acid that ionises completely in water
• what is a weak acid?

  an acid that partially ionises in water
• what does an acid and metal oxide produce?

  salt and water
• what does an acid and metal hydroxide produce?

  salt and water
• what does an acid and metal carbonate produce?

  salt and water and carbon dioxide
• what is oxidation in terms of electrons?

  loss of electrons
• what is reduction in terms of electrons?

  gain of electrons
• what is a dilute acid?

  low concentration of H+ ions