3. Heating by direct contact between particles is called

Which substances have the lowest melting points: ionic covalent, or metallic

What is the mass of 8 moles of sodium atoms

If you chip a tooth, most likely you will go to the dentist to have the missing material filled in. currently the material used to fill in teeth is a polymer that is flexible when put in, yet is hardened to the strength of a tooth after irradiation with blue light at a wavelength of 461 nm. what is the energy in joules for a photon of light at this wavelength?