What is the best clue you could use to decide: living thing or not a living thing?

A living thing grows, needs air, food and water, it reproduces and responds to changes.

The proton has a positive charge while the neutron has no charge they both make up the nucleus of the atom while the elections have a negative charge and surround the nucleus of the atom. the protons and electrons are used to calculate the atom's mass whereas the neutrons don't affect the mass