How do you determine the amount of proton, neutrons, and electrons an atom has?

Question

I already know you need to use the periodic table.

Answer 1

For a Normal Neutral Atom, the number of protons (p+), neutrons (n) and electrons (e-) are all the same.

Just look up the atomic number from the periodic table to determine them.

For example:

C: 6p, 6n, and 6e-.
N: 7p, 7n, and 7e-.
K: 19p, 19n, and 19e-.

Now, Determine the number of p, n, and e- for Ca.






If you guessed, 20p, 20n, and 20e-, you are Correct!


Note that, if you add the number of the atom's p and n you will get the Mass number (Z).

The periodic table shows Z of calcium as 40.078 because 20p + 20n = 40 (amu)

Another Example: Oxygen, having atomic number of 8, will have:
8p, 8n, and 8e-. This means that Oxygen will have the mass number of 16 because; p + n = Mass number (Z).

_____________________________________________________

For Isotopes:
Isotopes are atoms that have same number of protons but different number of neutrons.

You've already seen that normal Carbon has: 6p, 6n, and 6e-.

This normal carbon is called "Carbon-12". The "12" denotes its Mass number (Z). Which is p + n.

There are isotopes of Carbons and one of them are Carbon-13. Since you already know that Carbon must have 6p, Carbon-13 has 7n. 13 - 6 = 7. The number of the electrons are still the same as number of proton.

In another words, simply subtract the number of protons from mass number to determine the number of neutrons.

Now, determine the number of p, n and e- of Fluorine-19:





If you guessed 9p, 10n, and 9e-, you are Correct!

____________________________________________________

Finally, there are ions. Ions means that an atom has either gained or lost electrons. Keep in mind that eletrons are NEGATIVE in nature (e-) and when an atom Gains e-, it becomes More negative.

For example: Fluoride ion, F- means that it has GAINED one electron compared to its neutral F state. Therefore;

F has 9p, 9n, and 9e-, But F- has 9p, 9n, and TEN e-.

O has 8p, 8n, and 8e-, But O2- has 8p, 8n and TEN e-, because O2- means that it has Gained 2 more electrons than its normal O state.

Now, determine the p, n and e- for P3-.





If you guessed 15p, 15n, and 18e- you are Correct!

For atoms that have positive charges (cation), remember that they LOSE e- to become positive. So, Li+ has 3p, 3n and 2e-.
____________________________________________________

Keep in mind that you need to know how to combine all three of the ideas mentioned above. For example, you may be requested to determine the p, n and e- of Magnesium-25 ion.
You need to know that since Magnesium is in Group IIA, it will turn into 2+ ion. Therefore Magnesium-25 ion will have 12p, 13n, and 10e-.

I hope this answers your question. Good luck!

Answer 2

Go to Google

Type in: "Find How to Determine the amount of protons, neutrons and electrons an atom has"

Then his "Search" button

You will bring up list of sources to find your answer

CLICK "Genesis : Search for Origins | JPL | NASAE even the masses of protons, neutrons, and electrons are ratios of their mass ... is the outer electrons that determine the chemical properties of an atom..."

I have no idea what grade you are in. But if you need further information, try clicking the other sources.

Answer 3

The atomic number tells how many protons and electrons there are. To find the number of neutrons, subtract the atomic number from the atom's atomic mass.

Answer 4

The periodic table will tell you how many protons there are in the nucleus, and how many electrons orbiting it when the atom is electrically neutral. You then take that number from the given isotope number to find the number of neutrons. The isotope number can change, e.g. carbon-12 or carbon-14, uranium-235 or uranium-238, so these atoms have different number of neutrons. The different isotopes have different levels of radioactivity.

Answer 5

find out what a proton, neutron and an electron look like, then look at an atom under a microscope and count the amount of protons, neutrons and electrons

Answer 6

thats good you know about the periodic table.
Now just get the atomic number and atomic mass of the element..
Now, Atomic mass = protons (p) + neutrons (n)
and, the atomic number = no. of protons.
So, no of neutrons = Atomic mass - At. no.

For, the number of electron = no. of proton (p) in neutral atom.
Now if the atom is with 'n' positive charge over it,
no. of electrons = (p) - n
And if it has 'n' negative charge over it,
no. of electrons = p + n.

Got it.

Answer 7

protons = atomic number
protons = electrons
atomic weight = neutrons + protons

Answer 8

protons=electrons
protons+neutrons=atomic mass
protons/neutrons=atomic no
you should know any two of the above and you can calculate the rest easily.

Answer 9

number of protons = atomic number
number of electrons = atomic number
neutrons ~= mass - atomic number

Answer 10

go look on the periodic table of elements..