Question

questions:

1. what two subatomic particles make the mass of an atom?
2. do all atoms have the same number of protons, neutrons and electrons?
3. did you notice that two subatomic particles are always the same? so, which two?

____ and ____

1. atomic number tells you two things. how many ____ and ____
2. explain how to find neutrons:

Explanation:

1. Electrons have negligible mass, so protons and neutrons contribute almost all of an atom's mass.
2. Atoms can be ions (gain/lose electrons) or isotopes (different neutron counts), so these particle numbers vary.
3. In neutral atoms, the positive charge of protons balances the negative charge of electrons, so their counts are equal.
4. The atomic number is defined as the number of protons in an atom, and in neutral atoms, this equals the number of electrons.
5. The mass number of an atom is the total of protons and neutrons, so rearranging this gives the neutron count.

Answer:

1. Protons and neutrons
2. No
3. Protons and electrons
4. Protons; electrons
5. Subtract the atomic number (number of protons) from the mass number of the atom, i.e., $\text{Number of neutrons} = \text{Mass number} - \text{Atomic number}$