All chemicals elements are contained in the Periodic Table. This table arranges the elements according to their electronic structure. One of the clearest ways to define elements is whether they are...
If the outer shell of the nucleus is full of electrons then it is stable. In the first shell you are allowed 2 electrons after that you are allowed 8 electrons. If the out most shell does not have...
Simple answer: mammals have fur, reptiles and fish have scales, and birds have feathers. All three are simple variants of maturation in skin cells: if the cells just get thick, then you get scales....