Molecules and Atoms

Molecules and Atoms

as taught by 5th Period Chemistry

​Everyone ...

​please choose a whiteboard marker from the board.

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​Make sure everyone has a different color. :)

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​Whoever has the ...

​light blue marker, please go up to the board.

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​Explain to the class how we can figure out the number of atoms in a molecule of water.

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Now write the molecular formula for water (H₂O) on the board. Ask the class what the 2 means.

​What if we have two molecules of water?

​How many atoms of hydrogen are there?

​How many atoms of oxygen are there?

​Ask the class (especially if you don't know!)

​How would we write that there are two molecules of water?

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​Ask the students for guesses, then write those guesses on the white board.

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​Go to the next slide for the answer!

​2 H₂O

​If you guessed ...

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​then you guessed right!

​Whoever has the ...

​orange marker, please go up to the board.

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Light blue marker person can sit down.

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​Orange marker person, please draw a picture to explain to the class how many atoms of carbon are in 3 molecules of methane (CH₄).

​Methane looks like this ...

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Hint: draw 3 methanes then count the carbons.

How would we write this out? 

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Ask the class, write their guesses on the whiteboard, then press the spacebar to see the answer.  

3 CH₄​

​is the correct answer!

​Orange marker person, please sit down.

​Whoever has the green marker, please come to the board.

​Now, for something a little tricky ...

​ask the class how many atoms of

hydrogen are there in 3 molecules of

methane? Count them (the hydrogens are blue.)

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Write 3 CH₄ on the whiteboard.

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​How do the numbers work together to tell you the answer?

Ask a volunteer to draw arrows from the 3 to the C and

to the H to help show what happens.

​Now say ...

​"Class, do you understand how to determine the number of atoms in any molecule? Let me show you one, last example.:

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​Now explain to the class how many atoms of oxygen are in 6 molecules of acetylsalicylic acid ...

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​ ... just kidding!

​But I bet you could!

​Let's Practice a Few

​New teacher person, ask the class to tell you ...

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How many atoms of hydrogen are in 3 molecules of C₁₂H₂₂O₁₁ (sucrose)?

​How many atoms of copper are in 20 Cu₂Se (copper selenide)?

​How many atoms of nitrogen are in 34 C₅H₅N₅O (guanine)?

​How many atoms of iodine are in 15 BaI₂ (barium iodide)?

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​Write down the answers from the class, then go to the next slide to see if they are correct.

​How many atoms of hydrogen are in 3 molecules of C₁₂H₂₂O₁₁ (sucrose)?

​66 hydrogen atoms (because 3 times 22 is 6).

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​How many atoms of copper are in 20 molecules of Cu₂Se (copper selenide)?

​40 copper atoms (because 20 times 2 is 40).

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​How many atoms of nitrogen are in 34 molecules of C₅H₅N₅O (guanine)?

​170 nitrogen atoms (because 34 times 5 is 170).

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​How many atoms of iodine are in 15 molecules of BaI₂ (barium iodide)?

​30 iodine atoms (because 15 times 2 is 30).

​Please say ...

​"It's time for a quiz! Get out your markers, pencils, calculators, or whatever else you need.

Here we go!"

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​New teacher person, you may now sit down and take part in this quiz.

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​I want to say thank you to everyone today! 

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I miss you and hope to be back soon.  

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​If you have questions about any of this, just email me.  :)

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