Tuesday, August 22, 2017

Percent Composition

Percent composition is just like determining your grade - the amount you got divided by the the whole amount. 

With compounds, you find the mass of a particular element and divide it by the mass of the whole compound. So if you wanted to know the percent composition of oxygen in water, you would take the mass of oxygen and divide it by the mass of water. 


We practiced some basics and the students measured the amount of sugar found in DubbleBubble bubble gum. 


Students will each have a piece of gum and observe the gum by weighing it, drawing it, and smelling it. The students chew the gum for ten minutes. While they are waiting we will watch How Its Made on bubblegum.

After ten minutes, students will do more observations and re-weigh the gum. The gum weighed less... why? Because the sugar dissolved and was lost. Using this weight difference, students determined the percent composition of sugar in the gum they chewed. They also can convert the grams to moles and determine how many moles of sugar were in the gum.



Monday, August 21, 2017

What is a Mole? What does it have to do with chemistry?

Moles are used to count atoms. There are 22,000,000,000,000,000,000 quintillion atoms in a grain of sand and even counting grains of sand is a pain. Because atoms are so tiny, we use the mole to estimate.

There are 6.02 x 10 ^23 molecules in one mole. That's a whole lot. This is our new favorite number because it needs to be memorized. We will practice converting from moles to molecules.


Next we discussed molar mass. Molar mass = 1 mole and it also equals atomic mass from the periodic table. To find the molar mass of carbon dioxide you find the mass of carbon and two oxygens and add them together. Finding molar mass is not difficult unless the molecule has tricky subscripts (which we have been practicing).


The third thing about moles is that "one mole of any gas will occupy 22.4 Liters." 22.4 is another favorite number. We can convert from moles to liters and from liters to moles. 



Just how big is a mole? There's a TedEd talk on that! Watch it here!

Saturday, August 19, 2017

Conversions (Dimensional Analysis)

Conversions, or dimensional analysis, are used to change one unit to another. This is really useful when converting to metric units, but is essential to chemistry in terms of mole conversions. Setting up conversions is a skill so we started with learning the format. There are plenty of how to videos out there on the internet for anyone needing a tutorial.

We will practice conversions with some of the crazy things people do to get in the Guinness Book of World Records - like longest ear hair, skinniest waist, tallest man, etc. I think the one the kids thought was the weirdest was the lady who can pop her eyes out 12mm.

Check out more crazy records here!


Thursday, August 17, 2017

Theoretical and Percent Yield

Theoretical yield is how much product you can make with given reactants. To determine theoretical yield, do a normal stoichiometry calculation. 



Actual yield is how much is actually produced when the reaction is performed. 

Percent yield is how well you do. Percent yield calculates how close to the theoretical yield you are. A high percent yield means that your actual yield was close to the theoretical yield, the reaction worked the way it was supposed to it, and it was efficient and accurate. 

Why doesn't theoretical yield equal actual yield very often? ERROR!

Error can include impure substances, uncalibrated equipment, improper procedure... all kinds of things.

Percent error measures the amount of error. Small percent error means things went  well and the actual yield was close to the theoretical yield. 

Percent yield plus percent error should equal 100. 

Significant Digits and Scientific Notation

Significant digits are used so that our calculations are not more precise than our measurements. All digits other than zero are significant.
Its the zeros that are the tricky ones. We went over the rules and then did some practice situations. We will continue to practice this and all calculations made for the rest of the year must be rounded to the correct number of significant digits. 

Scientific Notation is used for very large and very small numbers that usually have a lot of zeros to make the numbers for manageable. Most students are familiar with scientific notation and just need a bit of practice. 

Monday, August 14, 2017

Chromatography

Chromatography is the separation of liquids based on particle or molecule size. 

Chromatography is used to separate inks into the colors that make them up. Most inks  are mixtures of colors and the ink will separate into bands of colors based on the size of the different ink molecules.The small particles move faster and will move further up the paper strip (in the photo black); the larger particles do not move as far (yellow). Some black inks are actually made up of blue red, pink, and yellow.

Pairs or groups of students received a strip of filter paper and made a pencil line about 3 cm from the end. They then traced over the pencil line with a marker, dipped the edge of the paper into water and waited. Over time the water will travel through the paper carrying the ink molecules with it. Smaller molecules are easier to carry and travel further.

Chromatography can be used to separate any mixtures with different size particles and actually gel electrophoresis used for DNA analysis works on a similar principle.



Friday, August 11, 2017

LD50

This week's topic is about lethal doses and LD50.

The second portion is about the difference in toxicity of natural vs. manmade chemicals. Most people wrongly assume that if a chemical is natural that is good and that if a chemical is manmade then it is bad. Both can be good and both can be bad!



Compound Interest's original post about Lethal Doses of Common Chemicals can be found here
Compound Interest's original post about Natural vs. ManMade Chemicals can be found here

Thursday, August 10, 2017

Expanding Horizons


Each week you will be asked to visit a few online sources. You may be asked to read an article, watch a video, play a game, take a quiz, listen to a podcast or all of the above. Sometimes you will be given specific questions to answer. At other times you will be asked to write a summary convincing others that they should check out what you found. These assignments will take time so do not wait until the last minute. At all websites, you will be asked to correctly write a citation.

Assignments will be given on Thursday and are due by the end of the school day on the following Thursday (for the first one you get 2 weeks because ROAR has not started). If you are absent, the assignment is due the day you return. 

This week is the first week! Start by taking a personality test at 16 Personalities!

Video 1: How the Elements Got Their Names
You may need to watch this video more than once and pause it.


Another fun video if you are interested!

“From Outer Space to Under Our Skin: A Look At The Universe”
http://ed.ted.com/featured/qwxLv7Xd#watch                    
This video is old, but interesting to think about. Note 100 = 1.

Please let MsJ know as soon as possible if you have problems or questions. 

Hazard Diamonds

Most of us have seen these diamonds on trucks as we pass them on the highway. These diamonds are useful for safety and response teams to identify what is in the truck so the correct precautionary and clean up measures can be made. 

The NFPA 704 fire diamond (or hazmat diamond) is described in NFPA Standard 704, maintained by the National Fire Protection Association. The system identifies four key hazards (health (blue), flammability (red), instability (yellow), and special (white)) and their degree of severity. Hazard severity is rated numerically, ranging from 0 (minimal) to 4 (severe).

The hazard diamond is useful because it allows emergency personnel to quickly and easily identify the risks posed by hazardous materials and is  useful to determine what, if any, special equipment should be used, procedures followed, or precautions taken during an emergency response. (Summarized & more information here.)



Want to make your own customizable hazard diamond? Click here. Why does this feature exist? So people can make easily identifiable hazard diamonds for any chemical they have on hand. 

Wednesday, August 9, 2017

Lab Equipment

Students need to be familiar with certain lab equipment and its purpose, even if we won't use all of it in labs for high school chemistry. Students identified equipment using examples of the real thing (we made this into a contest) and also by identifying black and white drawings.


Students will sort equipment based on what its main purpose is. Some equipment is used for liquids, some for solids, and some for heating. Some is used for all of those things. 

The three pieces of equipment most likely to come up, and the most confusing when in black and white photos are the watch glass, evaporating dish, and the crucible (which has a lid). All three of these can be used for heating substances to remove water among other things. In real life they look different - but in drawings they look similar. How to tell them apart? The watch glass resembles a contact lens; the evaporating dish has a pour spout; and the crucible is more cup shaped and often is pictured with a lid. 



Here is an online quiz on lab equipment with photos! Try it!

Tuesday, August 1, 2017

Welcome!

Greetings students, parents, and guardians.

Welcome to a new school year with Ms Jancaitis! This blog has been set up to connect students, parents, and guardians with the chemistry class.

Each student will receive a course syllabus. The course syllabus outlines what the course will be like, what topics will be covered, and course expectations. It also contains contact information. There will be a quiz on this syllabus on Friday.

Our first unit will cover lab safety and equipment. Each note packet comes with the safety rules and contract. The safety rules and contract need to be read and signed by both the student and parent guardian. The safety rules are rules designed to keep the classroom safe and orderly to maximize learning and prevent accidents and injuries. These rules need to be studied because there will be a safety test on Wednesday and infractions of these rules can lead to disciplinary action as well as low assignment grades. A contract holds students accountable for the items that are broken if the student is acting a manner that is unsafe for themselves or those around them.

Please have these papers signed and returned by Monday. Students not returning signed safety rules and safety contracts will not be able to participate in labs and activities until the contracts are signed and returned.

Monday, February 13, 2017

Periodic Trends

It is all about the electrons! Always!


Electro- negativity is how badly atoms want electrons. The most electronegative atoms are Fluorine, Chlorine, and Oxygen. Everyone wants to be a Noble Gas... and halogens are the closest so they are the most electronegative.

Ionization energy is how difficult it is to remove electrons. It is difficult to remove electrons from atoms that are electronegative.


Atomic radius increases as you move down the periodic table because atoms have more mass, but actually decreases from left to right because atoms are holding on to their electrons tighter (because they are more electronegative).

Shielding has to do with how protons are blocked by the electron shells - the more shells there are, the more blocking there is. So something in period 5 (with 5 shells) has more shielding than an element in period 2 with two electron shells. Sheilding is constant across the periodic table because the number of shells is constant.

Compound Chemistry has an infographic on the Periodic Trends here

Friday, February 10, 2017

Electronic Configuration

Battleship, a classic game by Milton Bradley, is a game easily adaptable to learning electronic configuration.

Electronic Configuration is an intense mathematical calculation proposed by Schrodinger & Heisenberg as a way to predict where to find an electron around the nucleus in the electron cloud model. 

There are four main parts of the periodic table known as orbitals. The S block, P block, D and F orbitals. Within each block, you just count over how many spaces it is. There are seven energy levels that are loosely based on the period that an element is (the D & F blocks are exceptions to energy levels). The D block is dumb and that's why it starts with one number lower. Really they just have less energy and have the same amount of energy as the S and P block in the 3rd period. The F block are failures and that's why they are 2 lower... or they have a lot less energy.

So to identify Hydrogen you would say 1s2 because it is in the first period or first energy level, in the s block, and the first member of the first block. Carbon is a 2P2 because it is in the 2nd period, in the P block, and the 2nd one over in the P block.

Students learned the pattern of electronic configuration and how to use it. Basically its like giving directions to an element on the PT using set landmarks. It is a bit confusing, but once you get the pattern, its not too bad.


Students practiced a bit and then they played Battleship to practice some more. The Periodic Table became the game board and students hid their ships on it, then guessed hits using the electronic configuration of the atoms. I think they really got the hang of it because I did not field many questions at that point.

Thursday, February 9, 2017

Expanding your Horizons: Alkali Metals

This assignment, students will watch two videos about the reactions of Alkali Metals with water (HINT - They will explode!!!)

Video 1 - Alkali Metals in water, accurate!

Video 2 - Brainiac - Alkali Metals 


Tuesday, February 7, 2017

Dudes (Chemistry Scientists)

There are several "dudes," famous chemistry folks that students need to be familiar with. These dudes (Democritus, Dalton, JJ Thompson, Millikan, Rutherford, Bohr, Heisenberg, De Broglie, and Planck) all did experiments and came up with different and improved atom models. The current model is the elctron cloud or quantum mechanical model which was formulated by Heisenberg and De Broglie.

Heisenberg and De Broglie came up with the current electron cloud model, but we draw Bohr's planetary model the most often because it easier to count the electrons. There's a TedEd video about the progression - HERE.

Electrons are tricky because they move constantly and at high speeds. Heisenberg's Uncertainty Principle states that you cannot know both the speed and location of an electron - you can only know one - because measuring either one, changes the other. DeBroglie's wave theory helps explain why electrons sometimes act like particles and sometimes are compared to waves.


For more information about the evolution of the atomic model, check out this link. And here is a video!

Here are some Dude Quizlet Flashcards to help you out.

Monday, February 6, 2017

Atoms and the PT

Atoms, or elements, are the smallest unit of matter. They retain their identity in chemical reactions and are combined to form compounds and everything in the universe.

Atoms have some basic parts. Protons and Neutrons are found in the nucleus and make up the atomic mass. To find the number of neutrons, you subtract the atomic number (number of protons) from the atomic mass number (protons plus neutrons).

Electrons are so tiny that they do not influence the atomic mass. They are found orbiting the nucleus in shells or orbitals. Atoms are neutral so the number of protons equals the number of electrons.

How small is an atom? Watch this entertaining TedEd video!

Mendeleev designed the periodic table by looking at the properties of elements on cards and arranging them different ways until he got a system that worked. No one told him how to do it, he just did it until it worked. He even left spaces for elements that were discovered in his lifetime. (More info about Mendeleev) His periodic table was set up according to atomic mass number. The current table, altered slightly by Moseley, is organized by atomic number (number of protons). This is an AMAZING Video about Mendeleev and his PT!

Next we discussed regions of the periodic table, colored them, and labeled them. Periods are horizontal rows (periods go at the end of a sentence) and there are 7 periods. There are 18 groups or families (vertical columns) and a few of them have special names. This a pretty excellent diagram. This website gives a lot of helpful information.




Friday, January 27, 2017

Percent Composition

Percent composition is just like determining your grade - the amount you got divided by the the whole amount. 

With compounds, you find the mass of a particular element and divide it by the mass of the whole compound. So if you wanted to know the percent composition of oxygen in water, you would take the mass of oxygen and divide it by the mass of water. 


We practiced some basics and the students measured the amount of sugar found in DubbleBubble bubble gum. 



Students each had a piece of gum and observed the gum by weighing it, drawing it, and smelling it. The students chewed the gum for ten minutes. While they were waiting we watched How Its Made on bubblegum.

After ten minutes, students did more observations and re-weighed the gum. The gum weighed less... why? Because the sugar dissolved and was lost. Using this weight difference, students determined the percent composition of sugar in the gum they chewed. They also can convert the grams to moles and determine how many moles of sugar were in the gum.



Thursday, January 26, 2017

Expanding Horizons: Insect Venom




The original Compound Interest article on insect venom and the Schmidt pain index can be found here. Please look at the graphics and read the article.


You can listen to an interview with Schmidt who developed the pain scale here (it is the first ten minutes) on a RadioLab podcast (I highly recommend their shows).





Still curious?
What's the difference between poison and venom? There's a TedEd Talk on that! Watch it HERE.

How does your brain respond to pain? There's a TedEd Talk on that! Watch it HERE!

Want to know more about ant colonies? There's a TED talk on it. Watch it here.

Wednesday, January 25, 2017

Moles? What the heck!

Moles are used to count atoms. There are 22,000,000,000,000,000,000 quintillion atoms in a grain of sand and even counting grains of sand is a pain. Because atoms are so tiny, we use the mole to estimate.

There are 6.02 x 10 ^23 molecules in one mole. That's a whole lot. This is our new favorite number because it needs to be memorized. We will practice converting from moles to molecules.


Next we discussed molar mass. Molar mass = 1 mole and it also equals atomic mass from the periodic table. To find the molar mass of carbon dioxide you find the mass of carbon and two oxygens and add them together. Finding molar mass is not difficult unless the molecule has tricky subscripts (which we have been practicing).


The third thing about moles is that "one mole of any gas will occupy 22.4 Liters." 22.4 is another favorite number. We can convert from moles to liters and from liters to moles. 

Just how big is a mole? There's a TedEd talk on that! Watch it here!

Tuesday, January 24, 2017

Conversions

Conversions, or dimensional analysis, are used to change one unit to another. This is really useful when converting to metric units, but is essential to chemistry in terms of mole conversions. Setting up conversions is a skill so we started with learning the format. There are plenty of how to videos out there on the internet for anyone needing a tutorial.

We practiced conversions with some of the crazy things people do to get in the Guinness Book of World Records - like longest ear hair, skinniest waist, tallest man, etc. I think the one the kids thought was the weirdest was the lady who can pop her eyes out 12mm.

Check out more crazy records here!


Monday, January 23, 2017

SigDigs and Sci Notation

Significant digits are used so that our calculations are not more precise than our measurements. All digits other than zero are significant.
Its the zeros that are the tricky ones. We went over the rules and then did some practice situations. We will continue to practice this and all calculations made for the rest of the year must be rounded to the correct number of significant digits. 


Scientific Notation is used for very large and very small numbers that usually have a lot of zeros to make the numbers for manageable. Most students are familiar with scientific notation and just need a bit of practice. 

Thursday, January 19, 2017

Expanding Horizons: How Big is a Mole?

Video Citation
Last Name, First initial. Middle initial. [Username if no real name is given (still last name, first name)]. (Year, Month Date). Title of video(underline). [Video File]. Retrieved from URL. 


    Typed Video Example:
AsapSCIENCE. (2015, March 15). What Happens If All The Bees Die? [Video File]. Retrieved from https://www.youtube.com/watch?v=JilYBVrFiLA



Video 1: How big is a mole? And what is a mole? A TED-Ed
Video 3: Why do your feet smell... and what can you do about it?



Just for Funsies


“From Outer Space to Under Our Skin: A Look At The Universe”
http://ed.ted.com/featured/qwxLv7Xd#watch                    
This video is old, but interesting to think about. Note 100 = 1.

Friday, January 13, 2017

Chromatography

Chromatography is the separation of liquids based on particle or molecule size. 

Chromatography is used to separate inks into the colors that make them up. Most inks are mixtures of colors and the ink will separate into bands of colors based on the size of the different ink molecules.The small particles move faster and will move further up the paper strip (in the photo black); the larger particles do not move as far (yellow). Some black inks are actually made up of blue red, pink, and yellow.

Pairs or groups of students received a strip of filter paper and made a pencil line about 3 cm from the end. They then traced over the pencil line with a marker, dipped the edge of the paper into water and waited. Over time the water will travel through the paper carrying the ink molecules with it. Smaller molecules are easier to carry and travel further.

Chromatography can be used to separate any mixtures with different size particles and actually gel electrophoresis used for DNA analysis works on a similar principle.


Thursday, January 12, 2017

LD50

This week's topic is about lethal doses and LD50.

The second portion is about the difference in toxicity of natural vs. manmade chemicals. Most people wrongly assume that if a chemical is natural that is good and that if a chemical is manmade then it is bad. Both can be good and both can be bad!




Compound Interest's original post about Lethal Doses of Common Chemicals can be found here
Compound Interest's original post about Natural vs. ManMade Chemicals can be found here