Alpha decay: complete the following equations (}^238U_{U)arrow _(90)^234Th+He

## Step 1:In alpha decay, a parent nucleus emits an alpha particle. An alpha particle is a helium nucleus, which means it has 2 protons and 2 neutrons.## Step 2:The atomic number (number of protons) and mass number (number of protons and neutrons) must be conserved in the reaction. The uranium (U) nucleus starts with an atomic number of 92 and a mass number of 238.## Step 3:When uranium-238 undergoes alpha decay, it emits an alpha particle, which is represented by a helium nucleus with an atomic number of 2 and a mass number of 4.## Step 4:To find the atomic number and mass number of the resulting thorium (Th) nucleus, we subtract the atomic number and mass number of the alpha particle from those of the original uranium nucleus.## Step 5:For the atomic number, we have . This gives us the atomic number of thorium.## Step 6:For the mass number, we have . This gives us the mass number of thorium.## Step 7:We now have enough information to complete the nuclear equation for the alpha decay of uranium-238.