Question

In general, how can you determine the mass number of the daughter product after alpha decay has taken place? How can you determine the atomic number?

Answer 1

Answer:

Explanation:mass of daughter nuclei gets reduced by 4 amu while atomic no reduced by 2

As each alhpa particle has mass of 4 amu and has 2 protons

Answer 2

Answer:

The mass of the daughter product is determined by subtracting 4 from the parent element.

The atomic number of the daughter product is determined by subtracting 2 from the parent atom.

Explanation:

• Let X be a parent element with atomic number Z and mass number A, then if X undergoes alpha decay then we get a daughter element Y with atomic number Z1 and mass number A1, and an alpha particle with atomic mass 2 and mass number 4.
• Alpha particle is basically a doubly ionised Helium atom with atomic number 2 and mass number 4.

Alpha decay

$X_Z^A \rightarrow Y_{Z1}^{A1} + He_2^4$

For a reaction the mass numbers and the atomic numbers must be balanced either side of the equation.

⇒ A = A1 + 4

⇒ Z = Z1 + 2

Hence, A1 = A - 4 and Z1 = Z - 2

Therefore, the mass of the daughter product is determined by subtracting 4 from the parent element.

And atomic number of the daughter product is determined by subtracting 2 from the parent atom.

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