chemistry paper 1

• how did niels bohr adapt the nuclear model?

  he suggested that electrons orbit the nucleus at specific distancees
• what did the experimental work of james chadwick prove?


  the existence of neutrons in the nucleus
• why do elements in the same group have similar properties

  they have the same number of electrons in their outermost shell.
• what were the problems with the early periodic table?

  not all the elements have been discovered and when elements were placed in order of atomic weight they ended up in the same group
• how did mendeleev overcome the problems of the early periodic table

  he left gaps for undiscovered elements and he changed the order of some elements
• what are the elements in group 1 known as

  alkali metals
• what happens when a group 1 element reacts with oxygen?

  alkali metal + oxygen -> metal oxide
• what happens when a group 1 element reacts with chlorine

  alkali metal + chlorine -> metal chloride
• what happens when a group 1 element reacts with water

  alkali metal + water -> metal hydroxide + hydrogen
• what colour vapour foes fluorine have?

  yellow
• what colour vapour does bromine have?

  red-brown
• what colour vapour does chlorine have?

  green
• what colour vapour does iodine have?

  purple
• what is the charge of an ion from group 1?

  +1
• what is the charge if an ion from group 2?

  +2
• what is the charge of an ion from group 6?

  -2
• what is the charge of an ion from group 7?

  -1
• what is an ionic compound?

  a giant structure of ions which are held together by strong electrostatic forces of attraction between oppositely charged ions
• what are the properties of ionic compounds?

  high melting and boiling point. don’t conduct electricity when solid but do when molten or dissolved.
• why do ionic compounds have high melting and boiling points?

  strong bonds between molecules which takes lots of energy to overcome
• why do simple molecules have low melting and boiling points?

  weak bonds between molecules and so little energy is needed to overcome these bonds?
• what is the structure of diamond?

  each carbon atom is covalently bonded to 4 others in a giant structure
• what are fullerenes?


  molecules of carbon atoms with hollow shapes
• why do some reactions appear to increase in mass?

  when substances react with gases in the air such as oxygen the mass will increase
• why do some reactions appear to decrease in mass?

  when a gas is a product of a chemical reaction, it is released into the atmosphere
• how do you calculate uncertainty?

  calculate the range in results and divide by 2
• what is the value of the avogadro constant?

  6.02 x 10(^23)
• what happens to metals when they react with other substances?

  metal atoms form positive ions
• what is the reactivity of a metal determined by?

  their tendency to make positive ions
• list metals in order of a reactivity

  • potassium
  • sodium
  • lithium
  • caclium
  • magnesium
  • zinc
  • iron
  • copper
• what is typically made when an acid reacts with some metals?

  salts and hydrogen
• how can acids be neutralised?

  adding it to an alkali
• what is the vernal word equation for a metal hydroxide with an acid?

  metal hydroxide + acid -> salt + water
• what is the general word equation for a metal oxide reacting with an acid?

  metal oxide + acid -> salt + water
• what is the general word equation for a metal carbonate reacting with an acid?

  metal carbonate + acid -> salt + water + carbon dioxide
• what type of ions do acids produce in a solution

  H+
• what type of ions do alkalis produce in a solution?

  OH-
• what can be used to measure pH?

  universal indicator or pH probe
• what is a pH of 7

  neutral solution
• what is a pH value less then 7?

  acidic solution