Question

An isotope of americium (Am) with 146 neutrons is used in many smoke alarms. (a) How many electrons does an atom of americium have? (b) What is the isotope's mass number \(A\) ? (c) Write its nuclear symbol.

Short answer

Answer: An americium atom has 95 electrons, and the nuclear symbol for this isotope is ${}_{95}^{241} \text{Am}$.

Step-by-step solution

Find the number of electrons

To determine the number of electrons, we first need to find the atomic number of americium. Americium has an atomic number of 95, which means it has 95 protons and, in a neutral atom, 95 electrons.

Calculate the mass number

The mass number (\(A\)) is the sum of protons and neutrons in an isotope. Since Am has 95 protons and 146 neutrons, the mass number can be calculated as follows: \(A = \text{number of protons} + \text{number of neutrons} = 95 + 146 = 241\) Hence, the mass number of this americium isotope is 241.

Write the nuclear symbol

Now that we have the atomic number (\(Z\)) and mass number (\(A\)) for the given isotope of americium, we can write its nuclear symbol: \({}_{95}^{241} \text{Am}\) So, the nuclear symbol representing this isotope of americium is \({}_{95}^{241} \text{Am}\). In conclusion: (a) The number of electrons in an atom of americium is 95. (b) The mass number (\(A\)) of the isotope is 241. (c) The nuclear symbol for this isotope of americium is \({}_{95}^{241} \text{Am}\).