Chlorine exists in two isotopic forms, $Cl-37$ and $Cl-35$ but its atomic mass is $35.5$. This indicates the ratio of $Cl-37$ and $Cl-35$ is approximately
- $1 : 2$
- $1 : 4$
- $1 : 3$
- $3 : 1$
The Correct Option is C
Approach Solution - 1
The correct answer is Option C) \(1 : 3\)
Let the relative abundance of \(Cl-37 = x\%\) then the relative abundance of \(Cl-35 = (100 - x)\%\)
Average atomic mass \(=\frac{x \times 37+\left(100-x\right)35}{100}\) \(=35.5\) \(\Rightarrow 37x+3500-35x\) \(=3550 \Rightarrow x=25\) \(\therefore 100-x=75\)
Thus, the ratio of \(Cl-37\) and \(Cl-35\) is \(x\) : \((100 - x)\) \(=25 : 75\) \(1 : 3\)
Read more from the chapter: Structure of Atom
Approach Solution -2
The correct answer is Option C) \(1 : 3\)
Real Life Applications
- The ratio of Cl-37 and Cl-35 in chlorine is used as a diagnosis in medicine. For eg: exposure to radioactive material
- The ratio of Cl-37 and Cl-35 in chlorine, helps in tracking the level of chlorine in the body
- The ratio of Cl-37 and Cl-35 in chlorine is used to measure the chemical reactions that involve chlorine.
Question can also be asked as
- Find the ratio of Cl-37 and Cl-35 in chlorine
- How does the ratio of Cl-37 and Cl-35 affect the atomic mass of chlorine?
- What is the significance of the atomic mass of chlorine being 35.5?
Approach Solution -3
The correct answer is Option C) \(1 : 3\)
Protons, Neutrons, and electrons are the subatomic particles of the atom. The atomic number of the atom is the total number of protons present in the nucleus. It is denoted by the symbol Z.
Isotopes
If the elements have the same atomic number but have different mass numbers, they are called isotopes. These isotopes have different numbers of neutrons in their nucleus. They have the same chemical properties but vary in their physical properties. Example: Hydrogen has three isotopes ( protium, deuterium, and tritium).
Mass number
The sum of protons and neutrons present in the nucleus is called a mass number. It is denoted by A.
Isobars
On the other hand, if the elements have the same mass number and different atomic numbers, they are called isobars.
Read more:
| Related concepts | ||
|---|---|---|
| Mass number | Atomic number | Electronic configurations |
| Neutrons | Elements | Subatomic particles |
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Concepts Used:
Structure of Atom
Atomic Structure:
The atomic structure of an element refers to the constitution of its nucleus and the arrangement of the electrons around it. Primarily, the atomic structure of matter is made up of protons, electrons and neutrons.
Dalton’s Atomic Theory
Dalton proposed that every matter is composed of atoms that are indivisible and indestructible.
The following are the postulates of his theory:
- Every matter is made up of atoms.
- Atoms are indivisible.
- Specific elements have only one type of atoms in them.
- Each atom has its own constant mass that varies from element to element.
- Atoms undergo rearrangement during a chemical reaction.
- Atoms can neither be created nor be destroyed but can be transformed from one form to another.
Cons of Dalton’s Atomic Theory
- The theory was unable to explain the existence of isotopes.
- Nothing about the structure of atom was appropriately explained.
- Later, the scientists discovered particles inside the atom that proved, the atoms are divisible.
Subatomic Particles
- Protons - are positively charged subatomic particles.
- Electron - are negatively charged subatomic particles.
- Neutrons - are electrically neutral particles and carry no charge
Atomic Structure of Isotopes
Several atomic structures of an element can exist, which differ in the total number of nucleons.These variants of elements having a different nucleon number (also known as the mass number) are called isotopes of the element. Therefore, the isotopes of an element have the same number of protons but differ in the number of neutrons. For example, there exist three known naturally occurring isotopes of hydrogen, namely, protium, deuterium, and tritium.