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.
The Norway rat (Rattus norvegicus, Fig. 1) is a stocky burrowing rodent, unintentionally introduced into North America by settlers who arrived on ships from Europe. Also called the brown rat, house rat, barn rat, sewer rat, gray rat, or wharf rat, it is a slightly larger animal than the roof rat (Fig. 2).Adult Norway rats weigh an average of 1 pound (454 g). Their fur is coarse and usually brownish or reddish gray above and whitish gray on the belly.he presence of rats can be determined by a number of signs described below: Droppings may be found along runways, in feeding areas, and near shelter. They may be as large as 3/4 inch (2 cm) long and 1/4 inch (0.6 cm) in diameter. Fresh droppings are soft in texture.