How do you find the number of neutron, protons, and electrons in the nucleus?

Question

How do you find the number of neutrons, protons, and electrons in the nucleus? Is the number of protons the same as the atomic number? Im so confused. Im in 8th grade Chem so please don't use big words (hahaha) and quick answers please!!!

Answer 1

there are actually no electrons in the nucleus of an atom. you are correct in saying that the atomic number is the same as the number of protons. The number of nuetrons is equal to the atomic mass minus the atimic number. The number of electrons is equal to the number of protons and is equal to the atomic number.

for example:
fluorine has an atomic number of 9 and an atomic mass of 19. this means fluorine has 9 protons, 9 electrons, and 10 neutrons

Answer 2

The number of protons in the nucleus equals the atomic number of the atom.
(Example, Hydrogen is atomic number 1, it has 1 proton)

The number of electrons around the nucleus equals the number of protons in the nucleus in a neutrally charged atom (no net charge...it is not an ion).
(Example, a Hydrogen atom has 1 proton so it also has 1 electron)

The number of neutrons in the nucleus can vary depending on the isotope we are talking about.
To give a general answer...
To find the number of neutrons in the nucleus, subtract the number of protons from the atom's atomic weight.
# Neutrons = Atomic weight - # Protons
However, this answer is incomplete.
Atoms can exist in several different "isotopes"...meaning that the atoms all have the same number of protons in the nucleus, but the number of neutrons are different. Have you ever noticed that the atomic weights of atoms are usually decimals? This is because the number you see on the periodic table is an average atomic weight of all the naturally occurring isotopes. An individual atom only have protons and neutrons in whole-number ratios (you cannot have .487 of a neutron in other words). To get the number of neutrons in a specific isotope, you subtract the number of protons from the atomic weight of just that isotope.
For example, Hydrogen-1 (the -1 after the name refers to the atomic weight of the isotope), has 1 proton and no neutrons. Hydrogen-2 has 1 proton and 1 neutron, and Hydrogen-3 has 1 proton and 2 neutrons. Hydrogen only has 3 isotopes; other elements can have many more.

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Answer 3

The atomic number is the number of protons. This established what element it is - so if an atom has one proton it is a hydrogen atom not matter how many neutrons or electons are around.

Atoms usually have the same number of neutrons as protons (excpet for hydrogen) - when they differ this is called an isotope (the element is still the same). So hydrogen (which usually has no neutrons) can sometimes have one or two neutrons. Naturally it will be heavier but its still Hydrogen and still has an atomic number of 1.

Electrons never go near the nucleus.

Answer 4

No electrons in the nucleus. (If you want to know how many electrons are in the atom, it is the same as the number of protons, unless the atom is "charged" or is an ion. The there are more or less electrons, based on the charge.)

Number of protons = the atomic number
(Hydrogen's atomic number is 1, it has one proton.)

Number of neutrons = (approximately) the atomic weight - number of protons.

Answer 5

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How many protons, electrons and neutrons are in an atom of krypton, carbon, oxygen, neon, silver, gold, etc...?

To find the number of protons, electrons and neutrons in an atom, just follow these easy steps:

Step 1 - Gather Information

The first thing you will need to do is find some information about your element. Go to the Periodic Table of Elements and click on your element. If it makes things easier, you can select your element from an alphabetical listing.

Use the Table of Elements to find your element's atomic number and atomic weight. The atomic number is the number located in the upper left corner and the atomic weight is the number located on the bottom, as in this example for krypton:

Krypton's data from the Table of Elements

Step 2 - The Number of Protons is...

The atomic number is the number of protons in an atom of an element. In our example, krypton's atomic number is 36. This tells us that an atom of krypton has 36 protons in its nucleus.

The interesting thing here is that every atom of krypton contains 36 protons. If an atom doesn't have 36 protons, it can't be an atom of krypton. Adding or removing protons from the nucleus of an atom creates a different element. For example, removing one proton from an atom of krypton creates an atom of bromine.

Step 3 - The Number of Electrons is...

By definition, atoms have no overall electrical charge. That means that there must be a balance between the positively charged protons and the negatively charged electrons. Atoms must have equal numbers of protons and electrons. In our example, an atom of krypton must contain 36 electrons since it contains 36 protons.

Electrons are arranged around atoms in a special way. If you need to know how the electrons are arranged around an atom, take a look at the 'How do I read an electron configuration table?' page.

An atom can gain or lose electrons, becoming what is known as an ion. An ion is nothing more than an electrically charged atom. Adding or removing electrons from an atom does not change which element it is, just its net charge.

For example, removing an electron from an atom of krypton forms a krypton ion, which is usually written as Kr+. The plus sign means that this is a positively charged ion. It is positively charged because a negatively charged electron was removed from the atom. The 35 remaining electrons were outnumbered by the 36 positively charged protons, resulting in a charge of +1.

Step 4 - The Number of Neutrons is...

The atomic weight is basically a measurement of the total number of particles in an atom's nucleus. In reality, it isn't that clean cut. The atomic weight is actually a weighted average of all of the naturally occurring isotopes of an element relative to the mass of carbon-12. Didn't understand that? Doesn't matter. All you really need to find is something called the mass number. Unfortunately, the mass number isn't listed on the Table of Elements. Happily, to find the mass number, all you need to do is round the atomic weight to the nearest whole number. In our example, krypton's mass number is 84 since its atomic weight, 83.80, rounds up to 84.

The mass number is a count of the number of particles in an atom's nucleus. Remember that the nucleus is made up of protons and neutrons. So, if we want, we can write:

Mass Number = (Number of Protons) + (Number of Neutrons)

For krypton, this equation becomes:

84 = (Number of Protons) + (Number of Neutrons)

If we only knew how many protons krypton has, we could figure out how many neutrons it has. Wait a minute... We do know how many protons krypton has! We did that back in Step 2! The atomic number (36) is the number of protons in krypton. Putting this into the equation, we get:

84 = 36 + (Number of Neutrons)

What number added to 36 makes 84? Hopefully, you said 48. That is the number of neutrons in an atom of krypton.

The interesting thing here is that adding or removing neutrons from an atom does not create a different element. Rather, it creates a heavier or lighter version of that element. These different versions are called isotopes and most elements are actually a mixture of different isotopes.

If you could grab atoms of krypton and count the number of neutrons each one had, you would find that most would have 48, others would have 47, some would have 50, some others would have 46, a few would have 44 and a very few would have 42. You would count different numbers of neutrons because krypton is a mixture of six isotopes.

In Summary...

For any element:

Number of Protons = Atomic Number

Number of Electrons = Number of Protons = Atomic Number

Number of Neutrons = Mass Number - Atomic Number

For krypton:

Number of Protons = Atomic Number = 36

Number of Electrons = Number of Protons = Atomic Number = 36

Number of Neutrons = Mass Number - Atomic Number = 84 - 36 = 48

Related Pages:

Element Math Game

All About Atoms

The Periodic Table of Elements

How many electrons fit in each shell around an atom?

How do I read an electron configuration table?

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This page is maintained by Steve Gagnon.


Citation and linking information

Answer 6

There are never any electrons in the nucleaus. They orbit around the outside. The atomic number will tell you how many protons. THe atomic weight will tell you how many protons and neutrons together.

Answer 7

Yes. Carbon 12, for example, has 6 protons and 6 neutrons.

Answer 8

atomic number is the number of protons,
ahhh shucks