In complete sentences, provide a short explanation (2-3 sentences) as to why the elements are organized as they are within the periodic table.

answer:

order generally coincides with increasing atomic mass. elements that occupy the same column on the periodic table (called a "group") mendeleev arranged the elements according to both atomic weight and valence. the iupac in december 2015, completing the seventh row, or period, on the table.

explanation:

i'd like to be brainliest and also i wanna be friends if its cool with you

the answer is na (sodium)