Name three different properties you can test before and after a chemical reaction to determine if a new substance was formed *

How will the emission of an alpha particle affect the atomic number of an atom

The table compares the number of electrons in two unknown neutral atoms. comparison of electrons atom number of electrons a 10 d 11 use this information to determine the number of valence electrons in the atoms. which of the following correctly compares the stability of the two atoms? both are unreactive. both are highly reactive. a is unreactive and d is reactive. a is reactive and d is unreactive.

Ineed ! i have no clue how to do this problem.