How can the number of valence electrons in an atom be determined and how does the number of valence electrons an element posses affect its behavior and properties?

Will give imagine you are given a mystery element. it is, however, a discovered and known element. you may perform a maximum of two observations or tests to determine its identity. time and money is critical, so you need to prioritize your tests. if you can get by with a single test, you get 100 super-geek points from your research lab team. pick your two tests, number them as #1 and #2, and justify why you think these two will certainly be enough (and why the first might well be enough all by itself.) the available tests are classification into metal, non-metal, or metalloid, count of valence electrons, count of electron shells, atomic radius (error range: +/- 1 pm), electronegativity (error range: +/- 0.1), first ionization energy (error range: +/- 10 kj/mole), melting point (error range: +/- 10 c), and boiling point (error range: +/- 20 c).