How many electrons, neutrons, and protons are in phosphorus? what is it's atomic number and mass number?

Which compound contains both ionic and covalent bonds? a) hbr b)cbr4 c)nabr d) naoh

What are the first two quantum numbers for the electrons located in subshell 4d? what are the first three quantum numbers for the electrons located in subshell 2s? how many electrons can be held in a sublevel l = 3? how many electrons can be held in the energy level n = 4? how many electrons in an atom can share the quantum numbers n = 4 and l = 3?

Who discovered a pattern to the elements in 1869?