Question

The percentage of occurance in a sample of 10Y5 and 11Y5 are 20% and 80% respectively. Find the atomic mass of the element.​

Answer 1

Answer:

The average atomic mass of the element is 10.8 u.

Explanation:

We have given the percentage of occurance in the nature of two isotopes of an element.

We have to find the average atomic mass of the element.

Now, the given isotopes of the element are ¹⁰₅Y and ¹¹₅Y.

The percentage of occurance of ¹⁰₅Y ( %₁ ) is 20 % .

And the percentage of occurance of ¹¹₅Y ( %₂ ) is 80 % .

Now,

Atomic mass of the first isotope ( A₁ ) is 10 u.

And the atomic mass of the second isotope ( A₂ ) is 11 u.

Now, we know that,

Average atomic mass = [ ( A₁ × %₁ ) + ( A₂ × %₂ ) ] / 100

⇒ Average atomic mass = [ ( 10 × 20 ) + ( 11 × 80 ) ] / 100

⇒ Average atomic mass = ( 200 + 880 ) / 100

⇒ Average atomic mass = 1080 / 100

⇒ Average atomic mass = 10.80

⇒ Average atomic mass = 10.8 u

∴ The average atomic mass of the element is 10.8 u.

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Additional Information:

1. Element:

A pure substance found in nature which cannot be distributed or separated by any physical or chemical changes is called as an element.

2. Atom:

The smallest and indivisible part of matter is called an atom.

3. There are mainly three particles of an atom namely proton, neutron and electron.

4. Proton:

The positively charged particle present in the nucleus of an atom is called as proton.

5. Neutron:

The chargeless particle present in the nucleus of an atom is called as neutron.

6. Electron:

The negatively charged particle present in the shells outside the nucleus of an atom is called as an electron.

7. Atomic number:

The number of protons or electrons present in an atom is called as atomic number.

It is denoted by "Z".

8. Atomic mass number:

The sum of protons and neutrons present in an atom is called as atomic mass number.

It is denoted by "A".

9. Isotope:

Some elements occur in nature in more than one form.

They have the same atomic number, but have different atomic mass number. Such elements are known as isotopes.

10. Average atomic mass:

1. There are various isotopes of some elements having different atomic mass.

2. It becomes difficult to decide a particular atomic mass in case of such elements.

3. Hence, average atomic mass is used to decide their atomic mass.

11. Formula to calculate average atomic mass:

• ᵃᵛᵉʳᵃᵍᵉA = [ ( A₁ × %₁ ) + ( A₂ × %₂ ) + ( A₃ × %₃ ) + ( Aₙ × %ₙ ) ] / 100

Where,

ᵃᵛᵉʳᵃᵍᵉA ⟶ Average atomic mass of element

A₁ ⟶ Atomic mass of the first isotope

%₁ ⟶ Percentage of occurance of the first isotope

A₂ ⟶ Atomic mass of the second isotope

%₂ ⟶ Percentage of occurance of the second isotope

A₃ ⟶ Atomic mass of the third isotope

%₃ ⟶ Percentage of occurance of the third isotope

Aₙ ⟶ Atomic mass of the nᵗʰ isotope

%ₙ ⟶ Percentage of occurance of the nᵗʰ isotope

Answer 2

Answer:

The average atomic mass of the element is 10.8 u

Explanation:

I Hope this helps you ❤️❤️