Each electron in an atom is described by four different quantum numbers. The first three (n, l, ml) specify the particular orbital of interest, and the fourth (ms) specifies how many electrons can occupy that orbital.able of Allowed Quantum Numbers. n l ml Number of orbitals Orbital Name Number of electrons 1 0 0 1 1s 2 2 0 0 1 2s 2 1 -1, 0, +1 3 2p 6 3 0 0 1 3s 2 1 -1, 0, +1 3 3p 6 2 -2, -1, 0, +1, +2 5 3d 10 4 0 0 1 4s 2 1 -1, 0, +1 3 4p 6 2 -2, -1, 0, +1, +2 5 4d 10 3 -3, -2, -1, 0, +1, +2, +3 7 4f 14.
Rat droppings are a key sign of a rat infestation; the mess and debris they leave in their wake is unmistakable. In addition to scattered nesting materials; debris from chewing, feeding and gnawing; rodents excrete urine and feces every few steps they take along their habitual paths of travel.
Rats also deposit small drops of urine on each other. This is called conspecific urine marking (conspecific means same species), and it occurs when one rat crawls over another and deposits a drop or two of urine, leaving a wet patch on the fur of the other rat (Grant 1963).