All matter is composed of molecules .
Molecules are composed of atoms , which consist of a nucleus surrounded by a cloud of electrons . The nucleus is composed of protons and neutrons , which are themselves composed of quarks . As stated in our privacy policy , we fully respect your privacy and will not use your e-mail address for any purpose other than the newsletter subscription. Search the Web with our sponsor, Overture. Without our visitors' support, Enchanted Learning would soon be off-line.