Unit 6

            This unit in chemistry, we added to our story on the composition and added more properties of the atom and about compounds and we did this through multiple labs and quizzes and homework packets.

            We started out with the Sticky Tape Lab. The purpose of the lab, ultimately, was to discover the electron, and some of the things it does. It helped us with our conductivity lab because we learned about nonmetal’s strong positive core and metal’s weak positive core making that makes metals conductive. It redefined our model of the atom as we learned that electrons stay together in a positive gas-like cloud.

            Next was the conductivity lab, its purpose was to introduce us to ionic compounds. It helped us learn about them because it showed us that when a metal and nonmetal are bonded they become neutral, which is a property of ionic bonding. When we put the ionic compound in water, we found that the bonds split water is polar, meaning it has a positive and negative side, and the metal became conductive in the solution.

            The difference between ionic compounds and molecular compounds is that ionic compounds are between metals and nonmetals and when bonded they become neutral. However, molecular compounds are between nonmetals and they do not become neutral, they are only focused on getting 8 electrons.

          

We also learned how to name ionic compounds. If it is a transition metal then you must name it with a roman numeral, and then end the nonmetal in –ide, for example; Iron (II) Chloride. If it is only a regular metal, then you do not write the roman numeral, but still end the nonmetal in –ide, for example; Sodium Chloride. We learned how to name ionic compounds with polyatomic compounds, such as Nitrate and Sulfite. In this case you use the same rules for naming with metals, but the nonmetal polyatomic compound ends with its corresponding ending, for example; Calcium Sulfate. Note how it is no longer ending in –ide. There is an exception with the polyatomic compound and ionic bonding naming with Ammonium (NH₄), where it actually replaces the metal, for example; Ammonium Nitrate. No other rules change in the naming.

Writing formulas for ionic compounds is another thing we learned. All you have to do is take the name, such as Zinc Nitride, and find the charge each has and find the amount of atoms of that specific element takes to cancel the electrons out. So the formula for Zinc Nitride would be Zn₃N₂. As Zinc has a +2 charge and Nitride has a -3 charge, you need 3 Zinc atoms and 2 Nitride atoms to make the compound neutral. If the ionic compound consists of a polyatomic compound, then the formula is a little different in looks, but the process is the same. Find the element/compound’s charges and write the formula so they cancel out. It will look something like this; Ca(ClO₃)₂ as Calcium has a +2 charge and Chlorate has a -1 charge, you must write parentheses to group the whole compound and then write the subscript for how many times it appears in the whole compound, if it only appears once, parentheses are not needed.

Molecular compounds are named differently from ionic compounds. If the first element only appears once then you do not need a prefix, but the second element, regardless of how many times it appears needs a prefix, the prefixes listed in order are mono for 1, di for 2, tri for 3 tetra for 4, penta for 5, hexa for 6, hepta for 7, octa for 8, nona for 9, and finally deca for 10. So the compound will look something like this; Carbon Dioxide, or Dihydrogen Monoxide, depending on the amount of times the element appears in the compound.

Writing the formulas for molecular compounds is pretty straightforward as you write the number of times each element appears in the compound. For example, it might look like CO₂ or H₂O, where you can tell by the prefix how to write the formula and which numbers to assign to which elements.

These are all of the major things we learned throughout Unit 6 in Accelerated Chemistry with the teacher that gives us pizza.

Unit 2

In Unit 2 in Accelerated Chemistry, the class learned about the relationships between volume, pressure, temperature, and number of particles.

First we did the lab on Pressure and Volume. In this lab we observed the relationship between pressure and volume and how to make particle diagrams based on what we observed. The class white boarded particle diagrams on pressure and volume and learned how to show a higher pressure using particle collisions. The more collisions represented by the diagram, the higher the pressure is and less collisions on the diagram show less pressure. We observe more collisions because as volume gets smaller, the pressure goes up and the particles are more likely to collide with other particles and the walls of our container. Also when the volume gets bigger the particles have more room to move and collide less often with each other and the walls of the container.

The next lab we did, Pressure and Number of Particles, we observed the relationship between pressure and the number of particles in a given volume and how to make diagrams and white board those diagrams to accurately represent what we observed. We observed that when the volume and temperature stayed the same, but the number of particles or pressure went up, the pressure or number of particles also went up and when either of them went down, the other went down as well. So, as we observed the relationship between pressure and number of particles, we observed that when the number of particles go up, there are more particle collisions being observed because the volume stays the same but there are more particles to collide with each other and the container so we measure a greater pressure.

In the third lab we did, Pressure and Temperature we observed the relationship between pressure and temperature when volume and number of particles are constant. We observed that when the temperature goes up, the pressure also goes up because the particles have more energy, move faster, and therefore are more likely to collide more often with the container or with other particles. We showed this in our particle diagrams by using more “wishees” as we call them, or lines behind particles to show direction/collision than we did in the previous labs of Pressure and Volume, and Pressure and Number of Particles. So if temperature increased in the final reading in contrast to the initial, we would draw more lines, or longer lines (as shown in the picture) behind the particles and also more collisions because the pressure has gone up as well.

The class learned how a thermometer works as well. Most thermometers now use an alcohol that is colored red. When the air temperature rises, the air particles collide more often with the glass tubing that encases the alcohol and transfer energy to it, speeding up its particles and causing them to collide more with the alcohol. The energy is then transferred to the alcohol causing its particles to speed up. Because the alcohol has nowhere to go but up, it expands upward until its particles don’t collide enough to keep moving up. The opposite happens when the air temperature goes down. The air particles collide less often with the glass, which then slows down its particles causing them to contract slightly and then transfers less energy to the alcohol causing the alcohol to contract as its particles cannot collide enough to keep it up.

Finally, the class learned about air particles and pressure using straws and how we do not “suck” substances through them, but we actually create a vacuum to bring the particles up through the straw. This causes near zero pressure pushing down on the liquid, and also almost zero air particles colliding with the liquid, forcing it through the straw and into our mouths. These are all of the things my Accelerated Chemistry class learned about regarding particle collisions in Unit 2.

Unit 1

In Accelerated Chemistry, I learned how to draw and interpret graphs, draw particle pictures, and use and apply mathematical models. After doing the first lab, Build a Boat Make It Float, the class white boarded on what our thought processes were on making our boat, discussed our best and worst features of our boats, and also explained why our boats did or did not work as we wanted them to. I then began learning about mass and also measuring mass.

I learned to draw particle pictures displaying what I saw but on the particle level. This helped me better understand mass and volume and also help me to know the different states of matter. I did a lab on this subject and I drew a particle picture for each different part. I learned a few new terms in the lab including: system, and environment/surrounding. The system is all the materials in a lab experiment such as a beaker, liquids, graduated cylinder etc. The system does not include the surrounding air or any other materials because that is the environment. I learned how to use these words while explaining my observations and I also was taught the Law of Conservation of Mass which also uses the words system and environment. The Law of Conservation of Mass states that in a system, mass can be reformed and changed in many ways, but the amount of mass will always stay the same unless particles of mass enter into the environment or they enter from the environment into the system. After a few labs I was taught more about physical and chemical changes. A physical change is most often only a change in a mixture’s color, smell, or a change in state, while a chemical change is when a substances particle composition is changed, when energy is released often in the form of temperature, and it can also be a change in color and smell but will most often be accompanied by another change. I then moved on to learning about volume and measuring it. I did a small lab where I observed the relationship between cm3 and mL using water.

I used something the class learned about called GAMMTRB to do the lab. GAMMTRB means to Graphically and Mathematically Model The Relationship Between two or more substances, or in the case of this lab was the relationship between cm3 and mL. After measuring the water in a graduated cylinder and then measuring the box that I poured the water into, I graphed the measurements. I learned how to read the graph and also read the equation of the graph to help me recognize any errors I made. Next I learned to find density by dividing mass by volume. Finally, I was taught how to use significant figures in my work of adding, subtracting, multiplying, and dividing while solving the different equations for density, volume, and mass.

Significant figures are a way of finding an estimated digit in a measured number and also a way to properly estimate any measured number found in an experiment. These are all the things I have learned in Accelerated Chemistry in the past few weeks.