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.
Answer:
a)Atomic number
Explanation:
Element symbol signifies the element. For eg, Na is sodium. Mass number is the sum of protons and neutrons of an atom of an element. Atomic mass is the molar mass of the given element. Finally, atomic number is unique to each element because it signifies the number of protons of that element. EACH ELEMENT has their UNIQUE number of protons. For eg, atomic number of hydrogen is 1 because it has 1 proton, NO OTHER ELEMENT HAS ATOMIC NUMBER 1 because NO OTHER ELEMENT HAS 1 proton.
Answer:
D or A
<em>But I do know...</em>
It's because new strains of the virus are constantly appearing and evolving, so the vaccine must change along with them.
Molarity is simply the ratio of the number of moles of a
substance over the total volume of the solution. Assuming that the addition of
0.850 moles does not change the overall volume of 1.70 L, therefore molarity is
simply:
Molarity = 0.850 moles / 1.70 L = 0.5 moles / L = 0.5 M
