All large radioactive atoms decay into smaller atoms by releasing alpha particles. Each alpha particle has 2 protons, 2 neutrons, and 0 electrons. The table below describes several neutral, low-mass atoms.

\begin{tabular}{|l|l|l|l|}
\hline \multicolumn{4}{|c|}{Stable Isotopes of Low-Mass Elements} \\
\hline Element Name & Symbol & \begin{tabular}{l}
Atomic \\
Number
\end{tabular} & \begin{tabular}{l}
Number of \\
Neutrons
\end{tabular} \\
\hline Hydrogen & [tex][tex]$H$[/tex][/tex] & 1 & 0 \\
\hline Helium & [tex][tex]$He$[/tex][/tex] & 2 & 2 \\
\hline Lithium & [tex][tex]$Li$[/tex][/tex] & 3 & 4 \\
\hline Beryllium & [tex][tex]$Be$[/tex][/tex] & 4 & 5 \\
\hline
\end{tabular}

An alpha particle is also referred to as a nucleus of which isotope?

A. lithium-7
B. helium-4
C. hydrogen-2
D. helium-2



Answer :

Let's break down the question step-by-step based on the information provided:

1. Understanding an Alpha Particle:
- An alpha particle consists of 2 protons, 2 neutrons, and no electrons.

2. Interpreting the Table:
- The table lists neutral, low-mass atoms with information about their element name, symbol, atomic number (number of protons), and number of neutrons.

3. Identifying the Matching Isotope:
- We need to find an element with 2 protons and 2 neutrons.
- According to the table:
- Hydrogen (H): 1 proton, 0 neutrons.
- Helium (He): 2 protons, 2 neutrons.
- Lithium (Li): 3 protons, 4 neutrons.
- Beryllium (Be): 4 protons, 5 neutrons.

4. Conclusion:
- The element that matches the criteria of having 2 protons and 2 neutrons is Helium.
- Specifically, Helium with 2 protons and 2 neutrons is known as the isotope helium-4.

Therefore, an alpha particle is also referred to as a nucleus of the isotope helium-4.