atomic structure and periodic table

• what is the radius of an atom?

  0.1nm
• whats the radius of a nucleus?

  1 x 10-14m
• what is the relative mass/charge of a proton?

  • mass = 1
  • charge = +1
• what is the relative mass/charge of a neutron?

  • mass= 1
  • charge= 0
• what is the relative mass/charge of an electron?

  • mass= very small
  • electron= -1
• what is the mass number?

  The total number of protons and neutrons in an atom's nucleus.
• what is the atomic number?

  The number of protons in an atom's nucleus.
• what are elements?

  substances made up of atoms with same atomic number
• what are isotopes?

  Atoms of the same element with different numbers of neutrons.
• what is the equation for relative atomic mass?

  sum of (isotope abundance x isotope mass number) / total abundance of all isotopes
• what are compounds?

  substance formed from two or more elements chemically bonded together in fixed proportions
• what are molocules?

  particles containing two or more non metal atoms bonded covalently
• what are mixtures?

  substances made up of different elements or compounds that aren’t chemically bonded to each other
• what is filtration?

  separates insoluble solids from liquids and solutions
• what is evaporation?

  separates soluble salts from solution
• how does evaporation work?

  1. slowly heat the solution in the evaporating dish
  2. crystals should form and dry out as solvent evaporates
• what is crystallisation?

  separates soluble salts from solution
• how does crystallisation work?

  1. heat solution
  2. cool solution when crystals start to form
  3. larger crystals should form as the solution cools
  4. filter crystals and leave to dry
• what are the two types of distillation?

  • simple
  • fractional
• what happened at the start of the 1800s?

  atoms described as solid spheres that cant be divided
• what happened in 1897?

  plum pudding model - ball of positive charge containing small negative electrons
• what happened in 1909?

  nuclear model - mass is concentrated in a positive nucleus with a cloud of electrons. alpha particles fires at thin sheet where some where deflected and most past straight through
• what happened in 1913?

  bohr model - electrons orbit nucleus in fixed shells
• what happened in 1932?

  james chadwick provided evidence that neutrons are neutral particles found in the nucleus
• how many electrons are allowed in the 1st, 2nd, and 3rd shell?

  • 1st= 2
  • 2nd= 8
  • 3rd= 8
• where is the lowest energy shell found?

  closest to nucleus
• how were elements ordered before the atomic structure was discovered?

  by atomic weight
• how did mendeleev develop the periodic table?

  • left gaps to keep groups together - new elements discovered later fitted into these gaps
  • swapped some elements around where ordering by the atomic weight did not fit the pattern - discovery of isotopes explained why elements can not be ordered by atomic weight
• how are elements ordered nowadays?

  increased atomic number
• what are the horizontal rows called in the periodic table?

  Periods
• what does the group number tell you?

  number of electrons in outer shell
• what does the period number tell you?

  number of shells with electrons in
• what are metals?

  elements that can form positive ions when they react
• what are non metals?

  elements that dont generally form positive ions
• how do metals get a full outer shell?

  losing electrons
• how do non metals get a full outer shell?

  gaining / sharing electrons
• how do metals get more reactive?

  by losing electrons more easily
• how do non metals get more reactive?

  by gaining electrons more easily
• where do metals get more reactive?

  bottom left of periodic table
• where do non metals get more reactive?

  top right of periodic table