Question

what is the missing particle?

144/60 nd→4/2 he+?

140/58 nd 140/58 ce 144/58 ce

Explanation:

Step1: Balance atomic number

Atomic number of \(_{60}^{144}\text{Nd}\) is \(60\), atomic number of \(_{2}^{4}\text{He}\) is \(2\). Let the atomic number of the missing particle be \(Z\). Then \(60 = 2+Z\), so \(Z = 58\).

Step2: Balance mass number

Mass number of \(_{60}^{144}\text{Nd}\) is \(144\), mass number of \(_{2}^{4}\text{He}\) is \(4\). Let the mass number of the missing particle be \(A\). Then \(144=4 + A\), so \(A = 140\).

Step3: Identify the element

The element with atomic number \(58\) is Ce (Cerium).

Answer:

\(_{58}^{140}\text{Ce}\)