How many molecules are in 1.28 mols of silicon dioxide​

7.71x10^23 molecules

Explanation:

Avogadro's # = 6.022x10^23

1.28 mol SiO2 x 6.022x10^23/ 1 mol SiO2 = 7.71x10^23 molecules

periodic trends is an atom that gets larger as the number of electronic shells increase, the radius of atoms increases as you go down a certain group in the periodic table of elements. in general, the size of an atom will decrease as you move from left to right of a certain period.