Me use the periodic table to identify the element represented by each of the following electron configurations. [he]2s2: ? [ne]3s23p5: ? [xe]6s1: ? [ar]4s23d9: ?

a sequence is a function whose domain is the set of natural numbers.

natural numbers are all the negative and positive integers

the old alchemists made significant contributions to science even though there starting premises were off a bit. their conclusions after failure would steer them into better directions for investigation. science is no more than close observation and the initial mistakes result in rethinking and retrying experiments.