a magnesium (Mg) atom with a mass number of 25 contains ?
To determine the number of subatomic particles in an atom, we need to understand the basic structure of an atom. An atom consists of protons, neutrons, and electrons.
The mass number of an atom represents the total number of protons and neutrons in its nucleus. In the case of magnesium (Mg), the atomic number is 12, which indicates that it has 12 protons. However, the mass number given is 25.
To find the number of neutrons in the magnesium atom, we subtract the atomic number from the mass number:
Number of neutrons = Mass number - Atomic number
Number of neutrons = 25 - 12
Number of neutrons = 13
Therefore, a magnesium (Mg) atom with a mass number of 25 contains 12 protons, 13 neutrons, and an equal number of electrons to maintain its neutrality.