Tumor markers are measurable biochemicals that are associated with a malignancy. They are either produced by tumor cells (tumor-derived) or by the body in response to tumor cells (tumor-associated). They are typically substances that are released into the circulation and thus measured in the blood.
â For example, the s subshell ( l = 0) contains only one orbital, and therefore the m l of an electron in an s subshell will always be 0. â The p subshell ( l = 1) contains three orbitals, so the m l of an electron in a p subshell will be -1, 0, or 1. â The d subshell ( l = 2) contains Â±ve orbitals, with m l values of -2, -1, 0, 1, and 2.
Each energy level (shell) has more subshells available to it: 1  The first shell only has the s subshell â¹ 2 electrons. 2  The second shell has the s and p subshells â¹ 2 + 6 = 8 electrons. 3  The third shell has the s, p, and d subshells â¹ 2 + 6 + 10 = 18 electrons. 4  The fourth shell has the s, p, d, and f subshells â¹ 2 + 6 + 10 + 14 = 32 electrons.