Answer:
Since different isotopes of an element have different numbers of neutrons (but always the same number of protons) they have different mass numbers. Nitrogen-14 and nitrogen-15 are both stable isotopes of nitrogen. However, the other 5 isotopes are all unstable.
Becquerel did not discover that the amount of exposure on the paper was proportional to the amount of uranium that was present in the rocks
<h3>What is radioactivity?</h3>
The phenomenon of radioactivity was discovered by the French scientist Henri Becquerel in 1896 when he placed photographic paper in a drawer with some radioactive rocks.
We have to note that Becquerel did not discover that the amount of exposure on the paper was proportional to the amount of uranium that was present in the rocks hence the stetement is false.
Learn more about radioactivity: brainly.com/question/1770619?
Explanation:
The answer to questions are
A) 4
B) 3
C) 5
D) 3
E) 3
Answer:
<em>What can be added to an atom to cause a nonvalence electron in the atom to temporarily become a valence electron </em>is<u><em> energy</em></u><em>.</em>
Explanation:
The normal state of the atoms, where all the electrons are occupying the lowest possible energy level, is called ground state.
The <em>valence electrons</em> are the electrons that occupy the outermost shell, this is the electrons in the highest main energy level (principal quantum number) of the atom.
So, a <em>nonvalence electron</em> occupies an orbital with less energy than what a valence electron does; in consequence, in order to a nonvalence electron jump from its lower energy level to the higher energy level of a valence electron, the former has to absorb (gain) energy.
This new state is called excited state and is temporary: the electron promoted to the higher energy level will emit the excess energy, in the form of light (photons), to come back to the lower energy level and so the atom return to the ground state.
I think it would be Bromine and Mercury, hope that helps
