chemistry paper 1

• Proton = mass 1 charge +1

  Electron = mass 0 charge -1

  neutron = mass 1 charge 0


  What are the charges and masses of protons, neutrons and electrons?
• they have equal numbers of protons and electrons


  why do atoms have no overall charge?
• made of only one type of atom


  what is an element?
• a substance made of more than one element chemically bonded together


  what is a compound?
• the number of protons in the nucleus


  what does the atomic number show?
• the number of protons and neutrons in the nucleus


  what does the mass number show?
• Atoms of the same element with the same number of protons but different numbers of neutrons


  what are isotopes?
• Average mass of all the isotopes of an element


  what is the relative atomic mass of an element?
• RAM = sum of (isotope abundance x isotope mass number) / sum of abundances of all the isotopes


  how can you calculate the RAM using mass numbers of its isotopes and % abundance?
• substances made of compounds and/or elements that aren't chemically bonded together


  what is a mixture
• filtration


  how can you separate an insoluble solid from a solution?
• fractional distillation


  how can you separate a mixture of liquids with similar boiling points?
• Chromatography


  how can you separate mixtures of liquids of different colours?
• as pencil is insoluble so won't dissolve in the solvent


  in paper chromatography, why must the origin line be in pencil?
• To stop the solvent evaporating

  why do you place a lid on top of the container in paper chromatography?
• heat in an evaporating dish on bunsen until almost all liquid has evaporated. Then leave solution to cool. Filter the crystals out of solution and leave in a warm place to dry


  how do you carry out crystallisation?
• at the top


  In fractional distillation, where is the coolest part of the column?
• John Dalton


  who described atoms as solid spheres in the early 19th century?
• J.J. Thomson (1897)


  Who discovered the electron?
• Plum Pudding Model


  What was JJ Thomson's atomic model called?

  
• James Chadwick (1932)


  whose experiments provided evidence of the neutron?
• most alpha particles went straight through. Some deflected and very few bounced back. This shows that there is a positive nucleus but most of the atom is empty space


  Rutherford and Marsden developed the nuclear model. They fired alpha particles at gold leaf. What did they show?
• electrons are contained in shells


  How did Niels Bohr develop the nuclear model?
• 2,8,8


  how many electrons fit in the 1st, 2nd and 3rd energy shell?
• the number of electrons in the outer shell


  what does the group number of an element tell you?
• the number of energy shells it has


  What does the period number of an element tell you about the atom?
• 2,8,2

  period 3, group 2

  Magnesium has an atomic number of 12. What is its electronic configuration? therefore, where is it in the periodic table?
• 2,8,7

  period 3, group 7


  Chlorine has an atomic number of 17. What is its electronic configuration? therefore, where is it in the periodic table?
• In order of relative atomic mass

  before Mendeleev's periodic table, how were elements arranged?
• He left gaps


  how did Mendeleev overcome early problems with the periodic table?
• Metals (left)


  What type of element forms positive ions when they react? Where can they be found on the periodic table?
• negative


  what kind of ions do non-metals form in ionic compounds?
• Alkali metals


  What are elements of group 1 called?
• Reactivity increases down the group


  state trend in reactivity as you go down group 1
• fizz on surface, produce hydrogen gas, produce a metal hydroxide (alkaline)


  how do alkali metals react with water?
• vigorously, to produce a white metal chloride salt

  how do alkali metals react with chlorine?
• alkali metal + water --> metal hydroxide + hydrogen


  What is the equation showing how alkali metals react with water?
• K is further down the group. Its outer electron is further from the positive nucleus and so is more shielded by electrons, making it easier to lose


  explain why potassium is more reactive than lithium
• they decrease


  What happens to melting and boiling points as you go down group 1?
• Halogens


  what are group 7 elements called?