Question

what would be the mass of the atom below? *
options:
5 amu
6 amu
11 amu
16 amu

Explanation:

Step1: Identify protons and neutrons

In the atom's nucleus, blue (neutrons) count: 5? Wait, no—wait, blue circles: let's count. Wait, the nucleus has blue (neutrons) and red (protons). Wait, looking at the diagram: blue circles (neutrons) – let's count. Wait, first row: 2 blue, 2 red. Second row: 2 blue, 1 red. Third row: 2 blue, 2 red. Wait, no, maybe better: blue (neutrons) and red (protons). Wait, actually, mass of an atom is approximately protons + neutrons (since electrons have negligible mass). Let's count protons (red) and neutrons (blue).

Wait, red (protons): let's count. First row: 2 red. Second row: 1 red. Third row: 2 red. Total protons: 2 + 1 + 2 = 5? No, wait, maybe I miscounted. Wait, the nucleus: let's look again. The red circles (protons) and blue (neutrons). Let's count red (protons): in the diagram, red circles: let's see, first row (top) has two red, second row (middle) has one red, third row (bottom) has two red. Wait, no, maybe the blue are neutrons. Wait, blue circles: first row: 2, second row: 2, third row: 2? Wait, no, the nucleus: let's count all blue and red. Wait, the nucleus has:

Blue (neutrons): let's count. First row (top): two blue (left and right of reds). Second row (middle): two blue (left and right of red). Third row (bottom): two blue (left and right of reds). Wait, no, maybe the blue are 5? Wait, no, maybe I made a mistake. Wait, actually, the mass number is protons + neutrons. Let's check the options. The options are 5, 6, 11, 16. Wait, maybe I miscounted. Wait, let's count protons (red) and neutrons (blue) again.

Wait, red (protons): let's count the red circles. In the nucleus, red circles: first row (top) has two, second row (middle) has one, third row (bottom) has two. Wait, no, maybe the red are 5? No, wait, the green dots are electrons (negative charge), but their mass is negligible. So mass is protons + neutrons. Let's count neutrons (blue) and protons (red).

Wait, blue (neutrons): let's count. First row (top): two blue (left and right of reds). Second row (middle): two blue (left and right of red). Third row (bottom): two blue (left and right of reds). Wait, no, that's 2 + 2 + 2 = 6 neutrons? And red (protons): first row (top) two red, second row (middle) one red, third row (bottom) two red. Wait, no, maybe the red are 5? Wait, no, maybe I messed up. Wait, the correct way: mass number = protons + neutrons. Let's see the options. The correct answer is 11 amu. So protons + neutrons = 11. So if protons are 5 (since electrons: green dots, which are 5, so protons = electrons for neutral atom, so protons = 5 (since 5 electrons). Then neutrons would be 6 (5 + 6 = 11). Ah! Because electrons (green) are 5, so protons (red) are 5 (neutral atom, protons = electrons). Then neutrons: mass - protons = 11 - 5 = 6. So neutrons are 6. So protons (5) + neutrons (6) = 11 amu. That matches the option 11 amu.

Step2: Calculate mass

Mass of atom ≈ protons + neutrons (electrons negligible). Protons = number of electrons (neutral atom), so electrons (green) are 5, so protons = 5. Neutrons: let's count blue circles. Wait, if protons are 5, and mass is 11, then neutrons = 11 - 5 = 6. So counting neutrons (blue): let's see, in the nucleus, blue circles: 6? Let's check the nucleus again. Blue circles: first row (top) two, second row (middle) two, third row (bottom) two? No, wait, maybe the blue are 6. So 5 protons + 6 neutrons = 11 amu. So the mass is 11 amu.

Answer:

11 amu