Which symbol represents an alpha particle?

Which symbol represents an alpha particle?

• A. ₂⁴He
• B. ₀¹n
• C. ₁¹H
• D. −₁⁰e

Answer: (A)

Alpha particles are helium-4 nuclei, made of two protons and two neutrons. Their symbol encodes this: mass number 4 and atomic number 2, written as ₂⁴He. This particle carries a +2 charge and is emitted in alpha decay. The other symbols correspond to different particles: a neutron has no charge and mass number 1 (₀¹n); a hydrogen nucleus is a single proton (₁¹H); and an electron has a negative charge (−₁⁰e). Therefore the symbol representing an alpha particle is the helium-4 nucleus.

Alpha particles are helium-4 nuclei, made of two protons and two neutrons. Their symbol encodes this: mass number 4 and atomic number 2, written as ₂⁴He. This particle carries a +2 charge and is emitted in alpha decay. The other symbols correspond to different particles: a neutron has no charge and mass number 1 (₀¹n); a hydrogen nucleus is a single proton (₁¹H); and an electron has a negative charge (−₁⁰e). Therefore the symbol representing an alpha particle is the helium-4 nucleus.