Problems are listed in approximate order of difficulty. A single dot (•) indicates straightforward problems involving just one main concept and sometimes requiring no more than substitution of numbers in the appropriate formula. Two dots (••) identify problems that are slightly more challenging and usually involve more than one concept. Three dots (•••) indicate problems that are distinctly more challenging, either because they are intrinsically difficult or involve lengthy calculations. Needless to say, these distinctions are hard to draw and are only approximate.
• The elements are generally listed in order of their “atomic number” Z (which is just the number of electrons in a neutral atom of the element). Hydrogen is first with Z = 1, helium next with Z = 2, and so on. There are 90 elements that occur naturally on earth, but they are not just numbers 1 through 90. What are they? What are the atomic numbers of the known artificial elements? (You can find this information in the periodic table inside the back cover.)
We need at least 10 more requests to produce the solution.
0 / 10 have requested this problem solution
The more requests, the faster the answer.