An alpha particle is a type of ionizing radiation ejected by the nuclei of some unstable atoms. It consists of 2 protons and 2 neutrons, which results in the helium-4 nucleus. This can be denoted by the symbol for helium, recognizing that an alpha particle is essentially a helium nucleus without the electrons.
To symbolize an alpha particle, we use the notation for the helium nucleus:
- The atomic number (number of protons) of helium is 2.
- The mass number (total number of protons and neutrons) for an alpha particle is therefore 2 (protons) + 2 (neutrons) = 4.
Putting this information together, an alpha particle is represented by:
[tex]\[ \prescript{4}{2}{\text{He}} \][/tex]
Let's look at the options provided:
a. \(\, _0^0 \text{He}\) - This notation suggests a helium nucleus with 0 protons and 0 mass number, which is incorrect.
b. \(\, _{-1}^0 \text{He}\) - This notation suggests a helium nucleus with -1 proton and 0 mass number, which is incorrect.
c. \(\, _0^{-1} \text{He}\) - This notation suggests a helium nucleus with 0 proton and -1 mass number, which is incorrect.
d. \(\, \prescript{4}{2}\text{He}\) - This notation correctly indicates a helium nucleus with 2 protons and a total mass number of 4, properly representing an alpha particle.
Therefore, the correct answer is:
[tex]\[ d) \, \prescript{4}{2}\text{He} \][/tex]
