What is the negative charge of an atom?

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?

How many moles of no2 will form when 3.3 moles of cu are reacted with excess hno3?

Name 3 types of energy you see being used as you look around a classroom