An atomic model shows 19 protons, 20 neutrons, and 19 electrons. What is the mass number of the atom?
The mass number of an atom is determined by the sum of its protons and neutrons. In this case, the atom has 19 protons and 20 neutrons, so the mass number would be 19 + 20 = 39.
The mass number is the sum of the number of protons and neutrons in an atom. In this case, the atomic model shows 19 protons and 20 neutrons. Therefore, the mass number of the atom would be 19 + 20 = 39.
To find the mass number of an atom, you need to add the number of protons and neutrons together. The protons and neutrons contribute to the mass of the atom, while the electrons have very little mass in comparison.
In this case, the atomic model shows that there are 19 protons and 20 neutrons. Therefore, the mass number of the atom can be calculated by adding these two numbers together:
Mass number = Number of protons + Number of neutrons
Mass number = 19 protons + 20 neutrons
Mass number = 39
So, the mass number of the atom in this atomic model is 39.