Question

Explain with examples (i) Atomic mass, (ii) Mass number, (iii) Isotopes and (iv) Isobars. Give any two uses of isotopes.​

Answer 1

The atomic mass is the mass of an atom. Although the SI unit of mass is kilogram, the atomic mass is often expressed in the non-SI unit dalton where 1 dalton is defined as ¹⁄₁₂ of the mass of a single carbon-12 atom, at rest

mass number

the total number of protons and neutrons in an atom

eg: shows in fig.

Isotope

The definition of an isotope is an element with similar chemical make-up and the same atomic number, but different atomic weights to another or others. An example of an isotope is Carbon 12 to Carbon 13.

Use

Radioactive isotopes find uses in agriculture, food industry, pest control, archeology and medicine. Radiocarbon dating, which measures the age of carbon-bearing items, uses a radioactive isotope known as carbon-14. In medicine, gamma rays emitted by radioactive elements are used to detect tumors inside the human body. Food irradiation -- the process of exposing food to a controlled level of gamma rays -- kills many types of bacteria, making food safer to eat.

Isobar

differ in atomic number (or number of protons) but have the same mass number. An example of a series of isobars would be 40S, 40Cl, 40Ar, 40K, and 40Ca.

Answer 2

Answer:

( i ) ATOMIC MASS-

• Atomic mass is the weighted average mass of an atom.

• The atomic mass of the atom is the mass of the protons plus the mass of the neutrons

Eg. Let us take the example of hydrogen whose atomic mass is 1

       Protons - 1

       Neutrons - 0

⇒ Atomic mass = 1 + 0 = 1

( ii ) MASS NUMBER-

• The mass number is defined as the number of protons and neutrons in the nucleus

Eg.  Let us take the example of Carbon whose mass no. is 12

         Protons - 6

         Neutrons - 6

⇒ Mass number = 6 + 6 = 12

Note :    

• Atomic mass and Mass number are not the same.

• Atomic mass is the weighted average mass of an atom of an element based on the relative natural abundance of that element's isotopes.

• The mass number is a count of the total number of protons and neutrons in an atom's nucleus.

( iii ) ISOTOPES -

• Isotopes are defined as the atoms of the same element, having the same atomic number but different mass numbers.

Eg. There are 3 isotopes of hydrogen atom namely Protium, Deuterium and Tritium

( iv ) ISOBARS -

• Atoms of different elements with different atomic mass numbers, which have the same mass number, are known as isobars.

Eg. $Ca^{40}$, $Ar^{40}$, $Cl^{40}$

- USES OF ISOTOPES -

• An isotope of uranium is used as a fuel in nuclear reactors
• An isotope of cobalt is used in the treatment of cancer.
• An isotope of iodine is used in the treatment of Goitre

HOPE IT HELPS YOU..