periodic table

• what did neils bohr discover?

  electrons orbit the nucleus
• who invented the modern periodic table?

  mendeleev
• why did mendeleev leave gaps?

  so that elements with similar properties could be placed in the corrupt group when they were discovered
• how were the elements ordered in newlands' and mendeleev's periodic tables?

  atomic weight
• how are the elements ordered in today's periodic table?


  atomic (proton) number