Answer:
It might be responding variable.
Hi :)
The bottom number tells you how many protons you have in the nucleus of this element.
In Krypton-84, this means that you have 84 nucleons, where 36 of these are protons, and the remaining 48 are neutrons.
Hope this helps :)
Answer:
a) the atomic number is 15
b) the mass number is 15+16 = 31
c) element is phosphorus
d)Group 15 period 3
Answer: Ionic radii is half the distance between two ions.
Explanation: from top to bottom down an element group, ionic radius increases. This is because a new electron shell is added as you move down the periodic table.
Might Be wrong not sure :)
C. An atom of helium has its valence electrons in its first energy level, it wouldn't and can't satisfy the Octet rule as it only has 2 electrons, but with 2, it has a full shell, as the first energy level can hold only 2 electrons.
