Question #0442e

1 Answer
Feb 4, 2018

Answer:

Na is bigger than Mg because of one less proton in the nucleus to attract the outermost electron cloud

Explanation:

See the image below
www.learner.org/courses/chemistry/images/lrg_img/Mg_NaElectronShellsjpg

#Na# has 11 electrons and 11 protons thus it has the less effect on the outermost electron cloud.

#Mg# has 12 electrons and 12 protons, here there is an increase in proton number in the nucleus without any increase in the orbitals. the nucleus of #Mg# exerts more attractive force than #Na# and thus the size of #Mg# is smaller than #Na#.