1) Why could most elements be arranged in order of increasing atomic mass but a few could not? 2) What is the reason for chemical periodicity, why did similar properties repeat?

Astudent is asked to identify and element that is pale yellow brittle solid and does not conduct electricity. at which location in this periodic table would the element most likely be found?

The chemical equation below shows the reaction of sodium (na) and chlorine (cl) to form sodium chloride (nacl). 2na + cl2 → 2nacl in this equation, which of the following is a reactant? i. sodium ii. chlorine iii. sodium chloride

Why is it possible for different microorganisms to extract energy not only from carbohydrates and other biological molecules but from a large variety of substances?