蜘蛛絲 7

The mass of an atom is mostly the mass of the nucleus.

(physics)

(Your core knowledge, physics in my case. -- Me@2014-01-27 07:30:03 AM)

The size of an atom is the size of the shells.

(Other branches of knowledge + packaging + social)

— Me@2009.09.25

2014.01.27 Monday (c) All rights reserved by ACHK