Explanation:
5 trial, had an average destiny of 7.40. g/cm
1s2 2s2 2p6 3s2 3p6 3d10 4s2 4p1
Primero realizas la configuración electrónica que es la que te puse allá arriba.
Después miras el nivel en que termina, puede ser 1, 2, 3, 4 etc.
Entonces como el último número de la configuración electrónica es 4, entonces ese es el nivel
Y los electrones de el último nivel son los de Valencia
4s2, 4p1 sumas 2+1 que son los electrones que se encuentran en el último nivel.
por eso hay 3 electrones de valencia.
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?