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 6.02×1023 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.
Mole is a measure of atoms, using Avogadros constant as a scale, 6.02×1023. 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 (1/2)×6.02×1023 .
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 6.02×1023 of atoms. So say 10g of Hydrogen-1 will have 60.2×1023 of atoms, or alternatively 10 moles.
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 6.02×1023 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??
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.