The reason that elements in the same group all have similar chemical properties is because they all have the same
a- number of protons in the nucleus
b- number of neutrons in the nucleus
c- number of electrons outside the nucleus
d- number of electrons in the outer energy level

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?