Periodic Table History

In the modern periodic table elements are arranged by:

• atomic mass
• atomic number
• valence electrons
• number of isotopes

Why were there blank spaces left in Mendeleev's periodic table?                                              

• He didn't know what to put there.
•  Undiscovered elements not yet known.
• Multiple elements could have fit
• He forgot to add the elements in.

Used the law of triads to make a list of elements

• Mendeleev
• Dobereiner
• Mosely

Who arranged the periodic table by increasing atomic number?

• Mendeleev
• Rutherford
• Bohr
• Mosely

_______________ developed the first periodic table and arranged the elements in order of increasing atomic mass.

• Stevie Wonder
• Sasha Vujacic
• Dmitri Mendeleev
• James Mosely

Which property did Mendeleev use to order his periodic table?

• Shielding effect
• Eletronegitivity
• Atomic Weight
• Metallic Character