What is the change in atomic mass number when an atom emits an alpha particle?

When an atom emits an alpha particle, its atomic number will be reduced by two, and its mass number will be reduced by four since atomic number is the number of protons.

An alpha particle is essentially a helium nucleus composed of two protons and neutrons.

because natural gas is colorless, odorless, and tasteless, distributors add mercaptan (a chemical that smells like sulfur) to give natural gas a distinct unpleasant odor (it smells like rotten eggs). they locate the types of rock that are likely to contain natural gas deposits.