Period 4 element be dangerous in large enough quantities due to its radioactivity. Nickel (Ni) is an element in period 4, between cobalt and copper. Nickel is rare in the Earth's crust, mainly due to the fact that it reacts with oxygen in the air, with most of the nickel on Earth coming from nickel iron meteorites. However, nickel is incredibly common in the Earth's core; along with iron it is one of the two main components. Nickel is an important component of stainless steel, and in many superalloys. Copper (Cu) is an element in period 4, between nickel and zinc. Copper is
CU Online CU Online CU Online is one of the first fully accredited online education programs, created in 1996 by the University of Colorado Denver (CU Denver). With CU Online, the pedagogy of CU Denver faculty has been extended globally, allowing local students as well as international students to partake in the same education. Initially launching with three online courses, CU Online has expanded its catalog to over 450 CU Denver online courses, with 18 full CU Denver degree programs and 12 certificates that can be completed entirely online. The online courses themselves are considered just another option for CU Denver students,