Explain more about the periodic table

A table which sorts elements according to their elemental properties.

Explanation: An element has an atomic mass and an atomic number. The periodic table was devised so that we can sort elements in an array which defines its collective properties. In a periodic table we have rows and columns. While going across the columns we sort elements according to their valence shell electrons and while going down the rows, we sort elements according to their atomic mass number. 1st and 2nd column elements are akalis which have higher electronegativity and have metallic character. Then comes semi-metals and metalloids. They have varying metallic properties with regard to the temperature. On right side of the table we have gases which have electron affinity: they attract electrons. Last column has noble gases. They have complete shells with electrons so they are least reactive. At the bottom, we have two rows they are metalloids from 4rth column and most of them are reactive elements.

c.

explanation:

i think it is true since you can test the answer and can use observations to complete it.