We started off the day checking in our homework from yesterday, the Calculating Molar Mass worksheet. The sheet can be found in the Unit 2 Handouts folder. Answers are as follows:
CaCO3 is ionic and is named calcium carbonate. It's molar mass is 100.09 g.
N2O6 is molecular and is named dinitrogen hexoxide. It's molar mass is 124.02 g.
Na2SO4 is ionic and is named sodium sulfate. It's molar mass is 142.05 g.
C8H18 is molecular and is named octane. It's molar mass is 114.26 g.
Fe3(PO4)2 is ionic and is named Iron (II) Phosphate. It's molar mass is 357.49 g.
Some things to remember about calculating molar mass:
Be careful with a polyatomic ion in parentheses, like (SO4)2. Since there are 2 atoms of SO4, there are 2 sulfur and 8 oxygen.
The masses of each element and your answer will always go to two decimal places.
The notes worksheet we filled out (titled Mole 1) can be found in the Unit 2 Handouts section.
First of all, we defined a mole. A mole is a unit similar to a dozen. Whilst a dozen contains 12 items... A mole contains 6.022×1023 items!
Then, we practiced a few molar mass problems. The answer to 2) is 44.01 g. The answer to 3) is 261.35 g.
It's been duly noted that sig figs don't come into play during molar mass problems, rather, every answer is rounded
to two decimal places.
Then, we started the real lesson: Mole conversions!
We wrote down a diagram to help us remember the conversion factors between moles, grams and particles.
The important thing to remember is: MOLES ARE THE CENTER OF THE UNIVERSE!!
So, moles go in the middle of all conversions, as this picture shows.
As you can all see, the conversion factor between mass (shown here as grams) and moles is the
molar massand the conversion factor between moles and particles (shown here as molecules)
is Avogadro's number. We will be using these conversion factors to solve these problems!
The first problem gave us the number 2.0 x 10-3 g of SnO2 and asked us to find how many moles were present in the sample.
First off, we need to name SnO2. It's correct name is Tin (IV) oxide. Next, we list what we have: 2.0 x 10-3 g of SnO2 Because we know g (grams) is a unit of mass, and we are trying to convert to moles, the conversion factor we are using is molar mass. We set up our equation. 2.0 x 10-3 g of SnO2 * 1 mol / ? g = our answer But how do we know how many grams to put on the bottom of our fraction? It's our conversion factor, the molar mass. We find the molar mass of SnO2 to be 150.71 g. Now, our equation reads: 2.0 x 10-3 g of SnO2 * 1 mol of SnO2 / 150.71 g of SnO2 = our answer Using our prior knowledge of dimensional analysis, we can solve this. Our answer is 1.3 x 10-5 mol of SnO2.
We completed another problem in class, 5a, using the same conversion factor but going from moles to grams and not the other way around. The answer to this one is 370 g of Li2CO3.
Our next problem, 6, was a bit trickier. Given 0.0908 g of nickel (II) chloride, find the number of molecules in the sample.
Molecules = particles. So, looking back at our diagram, we need to convert twice: once from grams of nickel (II) chloride to moles, and once from moles to particles.
First, we need to name nickel (II) chloride. It's name is NiCl2.
Then, we establish what we do know: 0.0908 g of NiCl2
Our first conversion will be from mass (grams) to moles, so we will use the molar mass to convert.
The molar mass of NiCl2 is 129.59. So the first conversion is...
0.0908 g of NiCl2 * 1 mol / 129.59 g
Now that we have converted from grams to moles, we now convert from moles to particles.
To convert from moles to particles, you use Avogadro's number. So, our full equation is...
0.0908 g of NiCl2 * 1 mol / 129.59 g * 6.02 x 1023 / 1 mol = our answer Canceling out the correct units and multiplying across, the answer is 4.22 x 1020.
Ms. Friedmann let us know that she's busy making lesson plans and hasn't had enough time to grade our quizzes or labs yet. Don't worry, Ms. Friedmann, we all still love you!
She also briefly discussed that only covalent (molecular) compounds make true molecules. The things that ionic compounds make are called formula units, although the terms are used interchangeably.
A tricky little thing about ionic compounds: although a compound like MgSO4 is obviously ionic, the bonding between the S and the 4 O's in the sulfate ion is molecular.
And last but not least... thanks for the laughs today KG. Or should I say Scotty :)
To start off class today, Mrs Friedmann went over the 3.1-3.2 web assign worksheet that was assigned for homework last night. This was checked in, but not collected. There is an answer key posted under Unit Two Keys on moodle.
MOLES AND MOLAR MASS
Mrs. Friedmann went over a powerpoint on moles for the rest of class. You can find the powerpoint under Unit 2 Notes in moodle.
We learned today that atoms are so small that we can only work with them in very large amounts. We find out how many atoms there are by weighing the samples. Moles let us work with grams to use weight to find the number of atoms in a sample.
Let's take Copper,
Copper has an atomic mass of 63.55, if we have 63.55 grams of copper, we have 6.02 * 10^23 atoms of copper, or one mole of copper.
The molar mass of an element is the same as its average atomic mass.
Examples:
12.01 g Carbon= 1 mole of Carbon
65.39 g Zinc= 1 mole of Zinc
30.97 g Phosphorous= 1 mole of phosphorous
Just like 2 is a pair, and 12 is a dozen, 6.02 * 10^23 is a mole
Now, let's talk about molecules:
Since compounds are not on the periodic table, we cannot find their average atomic mass
To calculate one mole of a compound, we must find the mass of the whole molecule. You do this by adding up the average atomic masses of all the atoms in the compound
Example:
Water has two hydrogen atoms and one oxygen atom
mass of H: 1.01
mass of O: 16.00
So: (2 * 1.10 g H) + (1* 16.00 g O) =18.02 g H2O
How big is a mole?
To put it into perspective, Mrs Friedmann gave us these examples:
One mole of watermelon seeds would be found in a watermelon slightly larger than the moon
One mole of donut holes would cover the earth to a depth of 5 miles
One mole of pennies would make at least seven stacks that would reach the moon
If you have a mole of pennies and spend a million dollars a day and died at the age of 100, you would still have 99% of your money after your death.
The homework for tonight is to complete the Calculating Molar Mass Worksheet
We began class today by going over the answers to the following handouts.
Names and Formulas of Ionic Compounds
Classification of Elements
Naming Practice
These can all be found in the Unit 2 Handouts folder on the Moodle Page. Below are some of the problems we reviewed in class that may have been difficult!
Names and Formulas of Ionic Compounds
3d) Name the following compounds that contain polyatomic ions.
Cu3PO4
Remember the rule for naming compounds with polyatomic ions is as follows:
Name the first metal present. Then, name the polyatomic ion. Names for polyatomic ions can be found at the top of our periodic table handout.
So, our the first element present is copper (Cu). PO4 is a polyatmic ion known as phosphate. Thus the name of the given compound would be copper phosphate.
TIP: Anytime you see 3 elements together, one of which is metal, in a compound, it is likely there is a polytamic ion present.
6l) Write the formulas for the following compounds.
Magnesium Hydroxide
We should first recognize that Magnesium is the element Mg, an alkali earth metal with a charge of +2.
Hydroxide is a polyatomic ion. It is written as OH and has a charage of -1.
Remember, when writing compounds, the charges of the ions present must ¨cancel out¨ or balance the equation.
Since Mg has +2 charge, it requires two -1 charge OH ions to bond to in order to balance the charges. So the answer is, Mg(OH)2. Remember to use parentheses when indicating more than one of a polyatomic ion.
7f) Name each of the following compounds.
MnO2
We should first recognize that the compound contains a transition metal (Maganese) and a non-metal (Oxygen). So, we should use our rule for naming compounds that contain a transition metal:
When naming a compound that includes a transition metal, include a roman numeral to tell the charge of the first transition metal. This is because transition metals are capable of forming multiple ions.
Oxygen has a charge of -2. This means 2 atoms with a -2 charge would have an overall charge of -4.
In order to balance the equation, the element maganese (Mn) would have to have an overall charge of +4.
Since there is only one atom of maganese present, as indicated in the original compound we know that this maganese has a charge of +4 or maganese (IV).
We can finish off our name of the compound by ending the non-metal (oxygen) with -ide, to become oxide.
Our answer is : maganese (IV) oxide
The concept of writing formula names with transition metals is a tricky one! Here is a video tutorial that can help:
Classification of Elements
Thise was one of the other two handouts that we reviewed briefly before the quiz. An amazing video can be found on the previous blog post that reviews everything you need to know on the periodic table.
Naming Practice
This was another handout we reviewed. For the handout the most important idea to understand is:
When a nonmetal combines with a nonmetal, use greek prefixes to indicate the number of atoms each element in the compound except in the case where the first element has only one atom. End the compound name in -ide.
Quiz
We took a quiz today that goes over everything we have learned since our last unit. We worked on the quiz with a partner but these quizzes will be graded individually. See Mrs. Friedmann if you missed the quiz, as you will need to make it up in the Test Center.
Homework
1) Read sections 3.1 and 3.2 in your text and complete the reading sheet (posted in the Unit 2 Handouts folder). Note that this is a WebAssign sheet, but I want you to answer the questions on the sheet and show them to me tomorrow in class rather than actually doing the WebAssign online. WebAssign has given us enough headaches lately!
Naming Covalent Compounds/Acids and the Periodic Table
Scribe: Grace Kilpatrick
Date: September 20, 2013
The main purpose for today´s lesson was to learn how to name covalent compounds and acids, as well as studying the organization of the Periodic Table.
Here is what we did in class today!
Notes
We first took notes on Naming Covalent Compounds. These notes can found in the Unit 2 Notes folder. Some important ideas include:
Prefixes indicate the number of atoms present for each molecule. These prefixes are.. mono- one, di- two, tri- 3, tetra- 4, penta- 5, hexa- 6, hepta- 7, octa- 8, nona- 9, deka-10.
Covalent bonds are bonds are between two non metals and are also known as molecular bonds.
The rule for naming covalent compounds is to say the name of the first element and its prefix, then the 2nd element with its prefex. End in ¨ide¨. Never use mono to say there is one of the first element at the beginning of the formula.
We then also took notes on Naming Acids. These notes can be found in the Unit 2 Notes folder. Some important ideas include:
An acid compound must start with ¨H¨.
If an acid does contain oxygen and an anions that ends with ¨ate¨, the ending of the acid is changed to -ic. (Remember if you ate something gross, you would say it is ¨icky¨!) If an anion ends with -ite, the ending of the acid is changed to -ous.
We also took notes on the periodic table. These can be found in the Unit 2 Notes folder as well. Some important notes include:
The major groups of the periodic table are alkali metals, alkaline earth metals, transition metals, halogens, noble gases, and lanthanides/actinides.
The group and element falls under allows us to draw conclusions about the ions it forms, as well as its reactivity.
Need further explanation on the periodic table? This is a great review video!
HANDOUTS
Today in class, we picked up the following three worksheets:
Names and Formulas of Ionic Compounds
Classification of Elements
Naming Practice Covalents
These can be found in the Unit 2 Handouts folder and should be completed for homework.
HOMEWORK
1) There will be a quiz on Monday on all the material we have learned this week (everything since our last unit test, including this weekend´s homework). 2) Three worksheets: ¨Names and Formulas of Ionic Compounds¨, ¨Classification of Elements¨ and ¨Naming Practice Covalents¨ (in the Unit 2 Handouts folder). 3) Three ChemThink tutorials and question sets: ¨Ionic Bonding¨, ¨Ionic Formulas¨, and ¨Covalent Bonding¨. Take notes on the tutorials to show me on Monday; one page in your journal should be enough space for all three sets of notes! The ChemThinks are due by 11:59 on Sunday night.
Hi everyone! I´d first like to apologize for the delay on this post. Here is what we did today.
NOTES:
First, we noted the location of the common polyatomic ions at the top of the sheet that contains our periodic table. This will be very useful to you.
Polyatomic: groups of atoms can have a charge too!
Examples:
NH4⁺¹ - ammonium ion
This entire molecule has a +1 charge. Ammonium is the ONLY positive polyatomic ion!
SO4²⁻ - sulfate ion
This entire molecule has a 2- charge.
(Note: You may use -2 interchangeably.)
OH⁻¹ - hydroxide ion This entire molecule has a -1 charge. **Treat each "clump" like ONE thing!** Charges need to balance out with these too! ex. potassium and nitrate ion
K⁺¹ and NO3⁻¹
becomes KNO3
Na⁺¹ SO4⁻² --> Na2So4
Mg⁺² NO3⁻¹ --> Mg(NO3)2
Al⁺³ OH⁻¹ --> Al (OH)3
NH4⁺¹ PO4⁻³ --> (NH4)3PO4
One should notice that when indicating there is more than one of a polyatomic ionic compound, the compound should be put in parentheses followed by the quantity present in order to balance the equation, as seen in the examples above.
These notes can also be found in the Unit 2 Notes folder on Moodle!
HANDOUTS:
We then went on to complete the worksheet titled:
Polyatomic Ionic Compounds: Name to Formula Using Crisscrossing
This can be found in the Unit 2 Handout Folder!
HOMEWORK:
1) Complete the Forming Ionic Compounds worksheet that was handed out on 9/18.
2) Complete the Naming Ionic Compounds worksheet (Parts A and B) that was handed out today. We have not discussed this topic in detail in class; refer to Chapter 2 in your text for help and do your best; we will continue practicing naming and forming ionic compounds tomorrow in class. Don't do the Naming and Forming Ionic Compounds sheet that was handed out today, we'll do it in class tomorrow.
3) 4 WebAssigns due tonight at 11:59 pm
4) No one has any ideas about the puzzle??? What does the image in the Unit 2 box stand for?! I will not tell you until someone figures it out!!! :)
EXTRA HELP?
Still don't understand the topic? Not a problem! Here's an extra video tutorial that can help!
This is a tutorial on writing formulas with polyatomic ions using the crisscross method!
Wednesday, September 18, 2013
Hey, Period 5.
Guess what day it is!!!
So back to the best part...Education!
In Class:
Today, as we walked into the classroom, we picked up four worksheets. These worksheets can be found on Moodle in the Unit 2 section under Unit 2 Handouts! Mrs. Friedmann checked the homework from the previous night (the Holy Atom, Batman! worksheet, the mini atomic structure worksheet, and our notes on atomic structure, ions, and isotopes from ChemThink). Something Mrs. Friedmann talked a little about was that it's fine to "walk away" if there's something that just frustrates you on an assignment. After, Mrs. Friedmann had us grab a buddy or two and work on the first worksheet. We worked a little on how to calculate the average atomic mass of isotopes as well.
Here is a video if you are still struggling with calculating average atomic masses :)
This video contains 3 isotopes and we only practiced with 2, but it's the same concept!
Notes:
In the beginning of the year, we talked a little about how there are two categories under matter:
Matter
Mixtures
Pure Substances
Pure Substances also split into two categories:
Pure Substances
Elements
Compounds
In class today, we discussed compounds in more detail. There are two types of compounds:
Ionic
Molecular (aka Covalent)
We didn't really talk about molecular compounds today, but we managed to talk about the two kinds of ionic compounds:
Cation ("CAT"-ion)
positively charged
goes first
usually metal; except NH₄⁺
Anion ("ANT"-ion)
negatively charged
goes second
always metal; except NH₄⁺
A Binary Ionic Compounds consists of one cation and one anion.
To form these compounds, the charges must cancel out.
Ex: Potassium & Fluorine
K⁺¹ F⁻¹
These elements will form a compound called KF. This is because their charges cancel out to equal 0.
We did not finish the notes in class. This is where we ended :)
Homework:
Finish the four WebAssigns by tomorrow night before 11:59 p.m.!
The four WebAssigns are the following:
Atomic Structure
Rdg - The Atom
Periodic Table
Rdg - The Periodic Table
Mrs. Friedmann was generous enough to give us a break from Chem tonight so be sure to thank her!
Today when we walked into class, Mrs. Friedmann was showing a Batman video on the board. If you would like to see the video again, you can click on the link below: http://youtu.be/nltVuSH-lQM
Homework
First, Mrs. Friedmann told us the homework for the day. It was the Holy Atom, Batman worksheet, the ChemThink worksheet, and the assignments on ChemThink. We are supposed to take notes on each tutorial assignment. All assignments are due tomorrow. Mrs. Friedmann also mentioned that WebAssign has been glitchy in the past few days, mainly around the hours of 9 P.M. through 1 A.M. She suggested to try to finish the WebAssigns before that time so problems don't occur.
Periodic Table
The class received a periodic table sheet.
Mrs. Friedmann told us to fold the piece of paper along the far left dotted lines. After folding the paper, she said to fold the paper so Beryllium matches up next to Boron, Magnesium matches up next to Aluminum, and all the way down the column. Mrs Friedmann said to write:
"+1" above the column with Hydrogen
"+2" above the column with Beryllium
"+3" above the column with Boron
Nothing above the column with Carbon
"-3" above the column with Nitrogen
"-2" above the column with Oxygen
"-1" above the column with Fluorine
"No charge" above the column with Helium
Then, we highlighted the metalliods, or semi-metals, which were: Boron, Silicon, Germanium, Arsenic, Antimony, Tellurium
PowerPoint on Periodic Table and Atom Structure
After we filled out our sheets, Mrs. Friedmann showed us a PowerPoint of the section. The PowerPoint can be found on Moodle under the Unit 2 Notes folder. The terms/topics covered on the PowerPoint were:
Who was Dmitri Mendeleev?
The 3 categories of the periodic table
Properties of Metals, Non-metals, and Metalloids
The periodic table groups and periods: Alkali metals, Alkaline Metals, Transition Metals, Halogen Family, Noble Gases, and the Rare Earth Elements
Protons, Neutrons, and Electrons
Atomic symbols
Isotopes
ChemThink
To end class, Mrs. Friedmann gave us some hints for ChemThink.
Protons + Neutrons = Mass Number
Protons - Electrons = Charge
Mass Number is different from average Atomic Mass
The identity of an element is its number of protons
Protons are the same as the Atomic Number
The next scribe is.... Chris H.
Hi, everyone! Thanks for posting your ratings of last week's tutorial animation on nerve gases (posted on Moodle...check it out if you haven't yet). Thought I'd share the results of my little survey with our scientific community (see below). Looks like the group overall gave it a C for interest level and a D for ease of understanding. I thought it was interesting that the average scores for both classes on ease of understanding were identical.
Today we started class by turning in our Beverage Density Lab. Ms. Friedmann then passed back our Unit 1 tests that we took on Thursday. The test was out of 80 points. The class did great by averaging 90% on the multiple choice section. If this impacts your grade negatively, don't worry! It is the first test and has a big impact on our grades at the moment but can easily be raised by the next test.
The Lab: The purpose of this lab is to investigate the physical and chemical properties of eight elements and to classify the elements as metals, nonmetals, or metalloids. Prelab Answers: 1) Hydrochloric acid is corrosive to skin and eyes. Copper Chloride is toxic. Although these samples probably won't be a problem, protect youself. Hydrochloric acid could burn but most likely won't. The best defense against damage is to be careful and use the skills we learned in the beginning of the year. After the lab you should definitely wash your hands to be sure. If your skin was contacted, it would take a couple of minutes to visibly appear.
2) Al- Aluminum- Marked as A
C - Carbon- Marked as B
Fe- Iron- Marked as H
Mg- Magnesium- Marked as F
Si- Silicon- Marked as C
S- Sulfur- Marked as E
Sn- Tin- Marked as D Zn- Zinc- Marked as G
Example of Aluminum
3) a. Physical property
b. Physical property
c. Chemical property
d. Physical property
e. Chemical property
f. Chemical property
This Lab should include:
Title- (example- Metal, NM, Metalloid Lab)
Purpose- Can be one stated on the handout!
Data Table- Data collected in Lab transferred to the google doc
Questions- Answered in complete sentences!!!- Questions 1-5
This Lab is shared on a Google doc with your classmates. It is due tomorrow and will be turned in as a group.
The next scribe is.... Peter D.!!! Thanks Peter for taking it!
(more info: http://www.webelements.com/technetium/)
