Alpha particles and helium atoms are similar in that they both consist of two protons and two neutrons, making them identical in terms of their nuclear composition. In other words, an alpha particle is essentially a helium-4 nucleus.
Both alpha particles and helium atoms have a relatively high stability due to their tightly bound nuclear structure. The strong nuclear force holds the protons and neutrons together within the nucleus, providing stability and preventing the nucleus from disintegrating.
However, there are also significant differences between alpha particles and helium atoms:
Charge: Alpha particles carry a positive charge of +2e, where "e" represents the elementary charge. In contrast, helium atoms are electrically neutral since they contain two protons (+2e) and two electrons (-2e) in order to balance the charges.
Size: Alpha particles are much smaller than helium atoms. An alpha particle is a compact particle, occupying a very small volume compared to the size of the electron cloud of a helium atom. The alpha particle's size is determined by the size of the nucleus, while the size of a helium atom is influenced by the electron cloud surrounding the nucleus.
Energy: Alpha particles are often emitted during certain types of radioactive decay, such as alpha decay. These particles possess significant kinetic energy as they are ejected from the nucleus. In contrast, helium atoms in their ground state have relatively low kinetic energy, and their behavior is governed by the electronic structure and interactions with other atoms or molecules.
In summary, alpha particles and helium atoms share the same nuclear composition, but they differ in charge, size, and energy. Alpha particles are highly energetic and positively charged, whereas helium atoms are electrically neutral and larger due to the presence of electrons surrounding the nucleus.