Why is the second ionization energy of any element higher than its first ionization energy?

Which of the following elements would you expect to have the lowest ionization energy value? fluorine, lithium, neon, nitrogen

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?

Amixture that has two or more substances that are spread out evenly is called a. compound b. heterogeneous c. substance d. homogeneous