# What is the mass in grams of one atom of a particular isotope? Consider 1 atom of C-12. The isotope notation is: 6 protons 6 neutrons 6 electrons X 1.67.

## Presentation on theme: "What is the mass in grams of one atom of a particular isotope? Consider 1 atom of C-12. The isotope notation is: 6 protons 6 neutrons 6 electrons X 1.67."— Presentation transcript:

What is the mass in grams of one atom of a particular isotope? Consider 1 atom of C-12. The isotope notation is: 6 protons 6 neutrons 6 electrons X 1.67 x 10 -24 g/proton = X 1.67 x 10 -24 g/neutron = X 9.11 x 10 -27 g/electron = 1.002 x 10 -23 g 5.466 x 10 -26 g 2.010 x 10 -23 g/atom 12 C 6

2.010 x 10 -23 g/atom is a very small amount. Scientists cannot measure small quantities like this in the lab. Scientists want (NEED!) to be able to work with a useable quantity such as 10 grams or 50 grams. Is there a convenient way to measure larger quantities of atoms?

Why not use the average atomic mass that is already on the periodic table? It is already a relative mass, right? Why reinvent the wheel?

But the atomic mass on the chart is in AMU, not grams! We do not have an AMU balance!

Then lets convert the number on the periodic chart from AMU to grams!

Lets review what we already know…….. We already know that 1 atom of C-12 has a mass of 2.010 x 10 -23 g. (This is also equal to 12 amu!) We also want the atomic mass of 12.0 amu to become 12.0 g. So, the problem becomes this…….. 2.010 x 10 -23 g/atom C-12 X ????? atoms = 12.0 g C-12

This quantity is called a MOLE. ????? = 6.0 x 10 23 atoms

A MOLE (mol) is just a word representing a quantity. What does dozen mean?Yep, it means 12. But 12 what? 12 steers 12 dinosaurs 12 flags

Just like the word dozen can stand for 12 things, the mole stands for 6.02 x 10 23 things. Things, however, are limited to AtomsMoleculesIons

You have finally arrived at the MOLE. You can now start applying this new knowledge in many different ways! Have Fun!

Stuff to Do With the Mole What is the mass of 1 mole of Cu atoms? How many moles of Cu atoms are there in 75 g of Cu? How many atoms of Cu are present in 200 g of Cu? What is the mass of 1 mole of Cu(NO 3 ) 2 ? How many moles of Cu(NO 3 ) 2 are there in 150 g of Cu(NO 3 ) 2 ? More mole problems are available at the ChemTeam Web Site. Visit it now!

This is easy! We just learned that 1 mole of an element is equal to the atomic mass listed on the periodic table. 1 mole of Cu atoms has a mass of 63.5 grams. What Is The Mass Of 1 Mole Of Cu Atoms? Menu Remember, 1 atom of Cu has a mass of 63.5 amu. 1 mole of Cu atoms has a mass of 63.5 grams!

This is easy! We just learned that 1 mole of a compound is equal to the sum of the atomic masses of each element in the compound. 1 mole of Cu atoms has a mass of 63.5 grams. + 2 moles of N atoms have a mass of 28.0 grams. + 6 moles of O atoms have a mass of 96.0 grams. What Is The Mass Of 1 Mole Of Cu(NO 3 ) 2 ? Menu One mole of Cu(NO 3 ) 2 has a mass of 187.5 g/mole.

How many moles of Cu atoms are there in 75 g of Cu? Molar mass Cu = 63.5 g/mol Use this as a proportion! X = 1.18 mol Menu If we know that… 63.5 gCu 1 mole = thenwe also know that… 75 g Cu x mole Another way to set this up…. 75 g Cu x 1 mole Cu = 1.18 mol 63.5 g Cu

How many moles of Cu(NO 3 ) 2 are there in 150 g of Cu(NO 3 ) 2 ? Molar mass Cu(NO 3 ) 2 = 187.5 g/mol Use this as a proportion! X = 0.8 mol Menu If we know that… 187.5 g Cu(NO 3 ) 2 1 mole = thenwe also know that… 150 g Cu(NO 3 ) 2 x mole Another way to set this up…. 150 g Cu(NO 3 ) 2 x 1 mole Cu(NO 3 ) 2 = 0.8 mol 187.5 g Cu(NO 3 ) 2

How many atoms of Cu are present in 200 g of Cu? You have to expand your mind a bit on this one. Is there a direct conversion between numbers of atoms and grams of an element? NO! Well, what do we know that will help us, then? We know there are 6.02 X 10 23 atoms in a mole of something. We know 63.5 g of Cu is equal to one mole of Cu atoms. How can we use these two facts to help us solve the problem?

How many atoms of Cu are present in 200 g of Cu? 1.Find out how many moles is equal to 200 g Cu. 2.Find out how many atoms there are in this many moles. 1. Molar mass Cu = 63.5 g/mol Use this as a proportion! 63.5 gCu 200 g Cu ------------ = -------------x = 3.15 moles Cu 1 mole x mole 2. There are 6.02 X 10 23 atoms of Cu in a mole of Cu. 6.02 X 10 23 atoms Cu x atoms Cu --------------------------- = ------------------- x = 1.9 X 10 24 atoms 1 mole Cu 3.15 moles Cu of Cu

How many atoms of Cu are present in 200 g of Cu? 1mole Cu6.02 x 10 23 atoms Cu 200 g Cu x ------------- x -------------------------- = 63.5 g Cu 1 mole Cu A much shorter way…Dimensional Analysis! x = 1.9 X 10 24 atoms of Cu Menu

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