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Number of Protons and Neutrons in Aluminium

How many protons and neutrons are there in Aluminium? 

The atomic number, Z of aluminium, Al is 13. Hence there are 13 protons. 

Note: Atomic number, Z represents the number of protons in a given atom.

Number of neutrons depends on the isotopic form of aluminium. More than 99.9% of naturally occurring aluminium is 13Al27.

Where 27 is the mass number, A; and 13 is atomic number, Z.


Mass number, A = no. of protons + no. of neutrons.


A = Z + no. of neutrons.


the number of neutrons in above isotope = A - Z = 27 - 13 = 14.

Note: The molar mass of aluminium, which is average of atomic masses of all isotopes = 26.981538 g/mol, since 13Al27 is the major isotope.

How do we know the number of neutrons in a given element?

Actually, the neutrons in one isotope of an element can be known from the data. For most of the stable isotopes, this number is nearer to proton number. But not always. It is advisable to remember this data for some important elements.

Though it is meaningless to say that particular element has "x" number of neutrons in it, however, if any one says like that, most of the time it refers to most abundant isotope. For example, you may have heard that hydrogen has no neutrons. In this case we are referring to the most stable and abundant isotope of hydrogen i.e., protium (1H1).

In the same way, we can also say aluminium has 14 neutrons and while doing so we should always keep in mind that we are citing 13Al27, the abundant isotopic form of aluminum.

Related questions 

1) Write the electronic configuration of aluminium?

2) What is the chemical nature of aluminium?

3) What is the third most abundant element in the earth crust?

4) Write the formula of alumina?

5) How many electrons are present in Al3+ ion?

6) Why aluminium dissolves in alkalies? Write the related chemical reaction.

7) What are the uses of aluminium? 

8) What is isotope? 


Author: Aditya vardhan Vutturi Google+ profile