Explain how the periodic table of elements is arranged and why the arrangement is significant

The periodic table is arranged of all of the known chemical elements an informative array. They're arranged in the order of the increasing atomic number. The rows are called periods and columns are called groups. Also, the elements with similar chemical properties are in the same group of elements.

It would be (at) + cu (s)

The mass has escaped into a gas which you can not see so the law stays true.