intro to chemistry help?

Question

I dont understand how to calculate the number of protons, neutrons and electrons. It says calculate the number of protons,neutrons,and electrons, in a. 13 is in the top left and 17 is in the botton right then it has CI, then 23/top left 11/bottom left and then Na, then it has 84/ top left 36/bottom left Kr. I have no idea what i am doing, i have never taken chemistry in my life so if anyone could break this down it would help me with the rest of my problems. Thanks!

Answer 1

In your Cl example, that should be an 18 top left, which is the number of neutrons in the isotope chlorine-35, and 17 bottom right, which is the atomic number. There are then 17 protons in the nucleus, 17 electrons outside, 18 protons, and 17+18=35 mass sumber.

In Na, 23 is the mass number (which is also the atomic weight, because Na has only one stable isotope in nature). The atomic number is 11, so 11 protons, 11 electrons, and 12 neutrons, because 11+12=23.

In Kr, atomic number 36, mass number 84. So 36 protons, 36 electrons, and 48 neutrons, because 36+54=84.

Answer 2

The top left number is the mass number. It is the total number of protons and neutrons in the atom.

The bottom left number is the Atomic Number. This is the number of protons in the nucleus of an atom.

In other words, the bottom left number would give you the number of protons and electrons. Then if you subtract this number from the one in the top left, you will get the number of neutrons.

So for Na with the 23 in the top left and 11 in the bottow left. You will have 11 protons, 11 electrons and 12 neutrons. For Kr with 84 in the top left and 36 in the bottow left. You will have 36 protons, 36 electrons, and 48 neutrons.

Answer 3

Na:
Protons = 11
Neutrons = 23-11 =12
Electrons = 11

Kr:
P= 36
N = 48
E= 36

the numbers are wrong for Cl (chlorine)