And atomic model shows 19 protons 20 neutrons and 19 electrons what is the mass number of the atom with the answer be 19 3920 or 58

Answer 1

The mass number of an atom is calculated by adding the number of protons and neutrons together. In this case, you have:

• Protons: 19
• Neutrons: 20

So, the mass number is:

\[ \text{Mass number} = \text{Number of protons} + \text{Number of neutrons} = 19 + 20 = 39 \]

Therefore, the mass number of the atom is 39.