20. The results of Rutherford's gold-foil experiment indicated that Calculate the density of copper, given that each copper atom contributes one free electron 24, there are 8.49 x 10"free e/cm' Cu. The atomic mass of copper is 63.54 g/mol electrons exist in the nucleus positive charge is concentrated in the nucleus positive charge is spread throughout the atom the nucleus has no electric charge 20. 21. An electron in the ground state 24 . can emit energy ordi itt cel A .coned Y can move to a lower energy level can remain in that state for only a fraction of a second 25. Find the number of free electrons per cubic centimeter in germanium at room temperature is at the lowest energy level given that there are 5.6 x 10- free electrons per atom. The density and molar mass of silicon are 5.32 g/cm' and 72.59 g/mol, respectively. latin .91-91# 101 is a massive, positively charged particle that moves at high speeds when emitted from radioactive materials. is the model of the atom that predicts only the probability that an electron is in a specific region. 25