Question

all large radioactive atoms decay into smaller atoms by emitting alpha particles. each alpha particle has 2 protons, 2 neutrons, and 0 electrons. the table below describes several neutral, low - mass atoms.

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

lithium - 7
helium - 4
hydrogen - 2
helium - 2

Explanation:

An alpha particle has 2 protons and 2 neutrons. The atomic number (number of protons) of helium is 2. The mass number (protons + neutrons) of an alpha particle is \(2 + 2=4\). So, an alpha particle is equivalent to a helium - 4 nucleus. Helium - 2 is not a stable isotope as it has an extremely low number of neutrons compared to protons. Hydrogen - 2 has 1 proton and 1 neutron. Lithium - 7 has 3 protons and 4 neutrons.

Answer:

helium - 4