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# WHAT is a mole?

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1. plz explain, explanations on google have led to this question.....
2. A mole is an amount. of whatever you're measuring.

It's defined such that 12g of Carbon-12 has 1 mole of atoms.
3. (Original post by alow)
A mole is an amount. of whatever you're measuring.

It's defined such that 12g of Carbon-12 has 1 mole of atoms.
would 12g of another element have 1 mole of atoms aswell, or is it just carbon?
4. (Original post by alow)
A mole is an amount. of whatever you're measuring.

It's defined such that 12g of Carbon-12 has 1 mole of atoms.
also, is 6.02*10^23 the number of atoms?
5. (Original post by p29)
would 12g of another element have 1 mole of atoms aswell, or is it just carbon?
Just carbon-12. For any element, if you have the mass number of grams of it, there is one mole, for example 1g of Hydrogen-1 has 1 mole of atoms.
6. (Original post by alow)
Just carbon-12. For any element, if you have the mass number of grams of it, there is one mole, for example 1g of Hydrogen-1 has 1 mole of atoms.
do any elements have more than 1 mole of atoms?
7. (Original post by p29)
do any elements have more than 1 mole of atoms?
What do you mean by that?

If you have more than the mass number of grams of an element there will obviously be more than 1 mile, by definition.
8. (Original post by alow)
What do you mean by that?

If you have more than the mass number of grams of an element there will obviously be more than 1 mile, by definition.
So the amount of moles in an element depend on how many atoms it has and its weight?
9. (Original post by p29)
plz explain, explanations on google have led to this question.....
A little animal that lives in the ground
10. (Original post by p29)
So the amount of moles in an element depend on how many atoms it has and its weight?
That question makes no sense.

What do you mean by "the amount of moles in an element"?
11. (Original post by alow)
that question makes no sense.

What do you mean by "the amount of moles in an element"?
amount/number
12. (Original post by cbreef)
An animal that lives in the ground
I wish
13. (Original post by p29)
amount/number
Still makes no sense. Do you mean the amount of moles in a sample?
14. (Original post by alow)
Still makes no sense. Do you mean the amount of moles in a sample?
On the periodic table, do all elements= 1 mole? even though all of the elements have different mass numbers?
15. Avogadro's number 6x10^23 is the number of atoms required to have the atomic mass of the atom in grams.

So if you have 16 grams of oxygen you have 1 mole of oxygen. If you have 12g of carbon 12 you have 1 mole of carbon 12.

It works this way because the atomic weight of carbon 12 is taken to be exactly 12 (by definition).

It makes the calculations easier for you to do. Don't sweat too much over it.
16. (Original post by p29)
On the periodic table, do all elements= 1 mole? even though all of the elements have different mass numbers?
I think you're getting confused.

(Original post by 1010marina)
Avogadro's number 6x10^23 is the number of atoms required to have the atomic mass of the atom in grams.

So if you have 16 grams of oxygen you have 1 mole of oxygen. If you have 12g of carbon 12 you have 1 mole of carbon 12.

It works this way because the atomic weight of carbon 12 is taken to be exactly 12 (by definition).

It makes the calculations easier for you to do. Don't sweat too much over it.
Yeah this. It's just an amount.
17. (Original post by p29)
amount/number
I think you need to go over the definitions of element, atom, molecule ect. to understand this better.

An element is a type of atom that can exist- it's not a physical thing. Since it's not a physical thing you can't ask how many of something make it up.

Substances are either made up of atoms or molecules (molecules are several atoms bonded together) and you have a mole of the substance when you have atoms or molecules. It's simply a number of things you can have, like a dozen.

Different atoms and molecules weigh different amounts, so moles of different substances do not weigh the same. The relative molecular mass of a chemical tells you how many grams one mole will weigh. This is found by adding up the relative atomic masses of all the atoms in the molecule which are given in a periodic table.
18. Mole is a measure of atoms, using Avogadros constant as a scale, . That is the definition, like 1kg is defined as the "mass of a particular international prototype made of platinum-iridium and kept at the International Bureau of Weights and Measures".

If you have an amount of an element, it can be measure in moles. Like you have grams or you have stones. It is a measure. Instead of measuring weight or volume, it measures atoms.

If you have a substance it has atoms in it. Instead of measuring the weight of that element that you have, you can use how many moles it has. It just so happens that 12g of Carbon-12 will contain 1 mole Carbon-12. That means that 6g of Carbon contain 1/2 mole of Carbon-12 or
.

So in a question, if you are told say "you have x grams of Carbon-12, how many moles of carbon-12 are there", your answer would be x/12 moles.

Take another element say Hydrogen as used above. We know that 1g will have of atoms. So say 10g of Hydrogen-1 will have of atoms, or alternatively 10 moles.
19. (Original post by sindyscape62)
I think you need to go over the definitions of element, atom, molecule ect. to understand this better.

An element is a type of atom that can exist- it's not a physical thing. Since it's not a physical thing you can't ask how many of something make it up.

Substances are either made up of atoms or molecules (molecules are several atoms bonded together) and you have a mole of the substance when you have atoms or molecules. It's simply a number of things you can have, like a dozen.

Different atoms and molecules weigh different amounts, so moles of different substances do not weigh the same. The relative molecular mass of a chemical tells you how many grams one mole will weigh. This is found by adding up the relative atomic masses of all the atoms in the molecule which are given in a periodic table.
ok so in order to have 1 mole of atoms for a certain element you end up with different mass numbers as atoms weigh different amounts, which is why different elements on the periodic table have different mass numbers as they all represent 1 mole??
20. (Original post by p29)
ok so in order to have 1 mole of atoms for a certain element you end up with different mass numbers as atoms weigh different amounts, which is why different elements on the periodic table have different mass numbers as they all represent 1 mole??
Kind of, but backwards:

All the mass numbers on the periodic table are in relation to carbon 12. They're all relative numbers, which means, they're unitless - if carbon 12 weighs 12 x (x could be grams, kilograms, etc.) then your hydrogen atom will weigh only 1 x. It's a relationship.

Avogadros number makes calculations using this fact easier. We measure in grams so we need a way of finding out how much 'stuff' is in a gram.

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