size and mass of atoms

• what does the atomic number tell you

  number of protons
• what makes an atom of an element the element it is

  the protons, e.g. if an atom has 8 protons, it must be oxygen
• what makes atoms of elements different to each other


  they have a different number of protons
• what is the relative mass of a proton

  1
• what is the relative mass of a neutron

  1
• what is the relative mass of an electron

  very small
• what is mass number


  the sum of the protons and neutrons in an atom
• what is an atom of element called which has the same number of protons but a different number of neutrons

  isotope
• why is the realtive atomic mass of chlroine not a whole number

  has more than one isotope
• how do the chemical properties of an isotope differ

  doesn't, has have the same number of electrons
• how do you work out the number of protons


  use the atomic (proton) number
• how do you work out the number of electrons in an atom

  same as the protons
• how do you work out the number of neutrons

  mass number - atomic number
• Atoms are very small, having a radius of about

  0.1 nm (1 x 10-10 m)
• The radius of a nucleus is less than

  1/10 000 of that of the atom (about 1 x 10-14 m).