00:02
Hi there.
00:03
In this question, we are tasked with determining the mass number for each of these elements.
00:10
And the mass number is defined as the sum of the protons plus the neutrons.
00:19
In other words, the total number of particles in the nucleus of the atom.
00:24
And the way that we can find the number of protons that each of these has is from its atomic number.
00:32
Because the atomic number is the same or equals the number of protons.
00:48
Okay, so knowing this information, we can go ahead and get started.
00:52
In letter a, we have a boron atom.
00:57
So looking at the periodic table, we see that the atomic number of boron is five.
01:02
So that means it has five protons.
01:06
And we see that it also has five neutrons.
01:09
So if we add the protons and the neutrons together, we get a mass number of 10.
01:16
So the mass number for this boron atom is 10.
01:23
The next one we have is magnesium atom.
01:28
Magnesium's atomic number is 12 looking at it on the periodic table...