Question

A neutral atom of an element has a nucleus with a nuclear charge 13 times and mass 27 times as that of hydrogen nucleus. What is the ratio of electrons to protons in its stable positively charged ion?
a.) 27 : 13
b.) 10 : 13
c.) 20 : 24
d.) 10 :14

Answer 1

Hint: We know that hydrogen is the first element of the periodic table. It has atomic number and mass number 1. The number of protons are zero and the number of neutrons are 1. To find the neutral element, just add the number to the hydrogen and you will get the element. The most stable state will be the nearest noble gas state.

Complete answer:
Let us move step by step to solve this question.
We all know that hydrogen atom has atomic number 1. It has mass number also 1. The number of protons are zero and the number of neutrons are 1.
Now, we are given that
Element with neutral atom has a nucleus with a nuclear charge = 13 times that of hydrogen
Element with neutral atom has mass = 27 times that of hydrogen nucleus
So, this element has number of protons = 13
The number of protons = Atomic number of an atom
So, the element has atomic number = 13
Thus, this element is Al that has atomic number 13 and mass number 27.
This is the neutral form.
The most stable state of Al is when it loses three electrons and achieves the nearest noble gas configuration. So, the stable state of Al has 13 protons and 10 electrons.
Thus, the ratio of electrons to the protons is 10 : 13

So, the option b.) is the correct answer.

Note:
It must be noted that Al has atomic number 13. It has one electron in ‘p’ orbital and two electrons in ‘s’ orbitals. By losing these three electrons, it achieves the configuration of neon which is stable. So, this is a stable state.