Quiz

• 1.

  Isotopes are elements with the same number of protons but a different number of neutrons
• Oxygen has 8 electrons, what is it's electron configuration?

  2,6
• Chlorine has 17 electrons, what is it's electron configuration?

  2,8,7
• 4.

  In order to be stable all atoms need a full outer shell of electrons
• How were elements arranged before the discovery of protons electrons and neutrons?

  In order of increasing atomic weight
• What two things did Mendeleev do to improve the periodic table?

  Mendeleev left undiscovered gaps for some elements and changed the order of some elements
• How was Mendeleev proven correct about undiscovered elements?

  Elements with properties predicted by Mendeleev were discovered and filled the gaps on his periodic table
• Why are group 0 elements unreactive?

  Group 0 elements all have a full outer shell of electrons
• Why does reactivity increase as you go down group 1?

  The outer electron is further from the nucleus so it is less attracted to the nucleus and so it is easier to remove. Also the shielding effect
• Why does the reactivity of halogens decrease as you go down the group?

  The outer shell becomes further from the nucleus so there is less attractive force so it is harder to gain an extra electron. Also the shielding effect