The science class decides to build an electromagnet. They wrap a strand of wire around a large iron nail three times, and connect the wire to a battery. The magnet is strong enough to lift a two pound metal plate. The class wants to be able to lift a four pound plate with the electromagnet. What should they do?

answer: atomic mass was originally used to arrange elements on the periodic table, but is no longer used to organize the modern version.

explanation:

originally atomic mass was used to arrange elements on the periodic table from left to right in a row. each column then shows similar properties of elements of a group.

in modern periodic table, the atoms are arranged in increasing atomic number. as atomic number represents the number of protons in an atom which is unique for every atom.