How are elements in the periodic table primarily organized?

By similarities in their chemical properties

What is the main reason that elements are placed in the same group in the periodic table?

They have the same number of valence electrons

They are all gases at room temperature

They have similar atomic masses

They are solid at room temperature

They have the same number of electron shells

They have identical chemical properties

They have the same atomic number

They have two valence electrons

They are all gases at room temperature

They have high ionization energies