How do I tell how many protons, neutrons, and electrons are in an element???

Question

i have a periodic table but i can't figure out how to find the protons, nuetrons, and electrons. for helium, all it says in the right hand corner is 2. plz help. thanks and God bless you!!!

on ones like Lr, lawrancium, all the side numbers say 2, 8, 18, 32, 32, 9, 2

what does this mean. plz help!!!!!!!!

on ones like Lr, lawrancium, all the side numbers say 2, 8, 18, 32, 32, 9, 2

what does this mean. plz help!!!!!!!!

Answer 1

Re: For Helium, the "2" is called the atomic number and it means that Helium has 2, protons, 2 nuetrons and 2 electrons.

For Lawrencium (Lr) it should show 103 as its atomic number. That means that Lr has 103 protons, 103 neutrons and 103 electrons.

The 2, 8, 18, 32, 32, 8, 3 numbers are showing electrons per shell (different subject) but you'll see that if you added all the numbers 2+ 8+ 18+ 32+ 32+ 8+ 3 = 103. 103 is the total number of electrons Lr has.

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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).

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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!

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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-.
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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

Don't look at the numbers in the right hand corner. Those indicate the number of electrons in each orbital. Helium has 2 electrons, so it only has one orbital. Copper has 2 electrons in the first orbital, 8 in the second, 18 in the third, and 1 in the fourth. This information is not needed for the question you asked.

The Atomic number is always located in the LEFT corner.

The first link below will take you to a comprehensive periodic table that you can print out if you need a better chart

The easy part - protons and electrons. Find the Atomic number (in the left upper corner).

Atomic Number = # of protons = # of electrons
Examples:
Helium has 2 protons and 2 electrons
Oxygen has 8 protons and 8 electrons
Copper has 29 protons and 29 electrons

Protons have a positive or (+) charge, and electrons have a negative or (-) charge. Atoms are 'considered' neutral or having no charge. So atoms must have an equal number of protons and electrons.

The harder part - # of neutrons.
Open the link below, and look at the number at the bottom. Helium should be 4.002602, oxygen is 15.9994, and copper is 63.546.

This is called the Atomic Weight. What you need is the atomic mass, but you won't find it on the periodic table. Luckily, it is easy to calculate.

Atomic mass = atomic weight rounded to the nearest whole number.

Example: Helium atomic mass = 4, Oxygen atomic mass = 16, and Copper atomic mass = 64

Now subtract the number of protons from the atomic mass to get the number of neutrons.

Example: Helium 4 - 2 = 2 neutrons
Oxygen 16 - 8 = 8 neutrons
Copper 64 - 29 = 35 neutrons

The second link below will take you to an interactive periodic table. It is helpful when practicing so that you know you are getting it right.

Hope this helps.

Silk Dragon (Chemical/Biochemical Engineer)

Answer 3

To find the number of protons and electrons for an element look at the atomic number. For example hydrogen, its atomic number is 1 so it has 1 proton and 1 electron. Oxygen atomic number is 8 so it has 8 protons and electrons. There are always the same number of protons and electrons. To find the neutron use the atomic mass of the element and round the number to make it a number without decimals and subtract it with the atomic number. Oxygen atomic mass is about 16. its atomic number is 8 so 15-8= 7.

Answer 4

To find the protons look at the atomic number of the element. For Helium (top right of the table) it should be 2.
The number of electrons is also the atomic number. For helium will be 2.
Now for the neutrons, look at the atomic mass. For Helium it should be 4.002. What you do next is take the integer closer to the atomic mass. In this case it is 4.

The number of neutrons will be then. 4 - number of protons = 2

If the atomic mass is 74.9 (less than a close integer)then you make it 75 (look for arsenic, element 33).

That's it.

Answer 5

Proton = the atomic number
Neutrons = the atomic weight - the number of protons
Electrons = the number of protons (assuming a neutral charge)

DO NOT assume the number of neutrons is equal to the number of protons.

If the charge is a negative number, you add electrons, if the charge is a positive number you remove electrons to find your answer.

Also the atomic weight is an AVERAGE based on what occurs naturaly. The number will not be a whole number in most cases, so you will have to round to the nearest whole number to find the number of neutrons.

Answer 6

well the number 2 that you found in the table is the electrons number so the helium has 2electrons... therefore 2 protons... and the neutrons I don't know.... I hope It helps you....

Answer 7

Most of the weight of an atom is due to the weight of the protons and neutrons. The electron is very small in comparison, size-wise

Answer 8

no of protons=no of electrons=atomic no of the element(which is usually written on lower left of the element)

mass no=no of protons +no of neutrons
(written on upper right of the element)
so,no of neutron=mass no-no of electons(=no of protons)