IMF's and fun

This week in chemistry we learned about forces of attractions. Some of the forces included intramolecular forces, the attractive forces that hold atoms together within a molecule, and intermolecular forces, the attractive forces that hold identical molecules together between molecules. Also we learned about the three types of IMF's. The weakest IMF is called dispersion forces (AKA London forces). These type of forces are formed when two molecules become close and the e- cloud of one repel the other e-cloud. The second type of force is called dipole-dipole forces. These forces are formed when molecules orient themselves so the the slightly negative end of one molecule is attracted to the slightly positive end of the nearby molecule. The last and strongest bond is called a hydrogen bond. A hydrogen bond is formed when electronegetive atoms cause a large partial positive charge on the hydrogen atom. We also learned about phase changes. Phase changes require energy to happen. Phase changes that absorb energy make the particles move faster and the IMF's duplicate causing melting and evaporating. Phase change that remove energy make the particles move slower and strengthened the IMF's causing freezing and condensation. Lastly we learned about the phase diagram. The temperature and pressure shown on the graph determine the phase of a substance and have opposite effects. Higher temperature causes more liquid to evaporate but higher pressure causes vapor to condense.  

This week we also did multiple labs that related to what we learned this week. One lab we did was the drops on a penny. We took water first then ethanol and dropped as many drops on the head side of a penny as we could until the water/ethanol spilled over. By doing this lab we learned that water had a stronger intermolecule force because we could as more drops of water to the head of the penny than ethanol drops.  

Another lab we did was the CO2 bubble, which was the best lab. In this lab we mixed water and dry ice to create a gas, then we took a strip of cloth and soaked it in soapy water. After this we took the strip of cloth and ran it over the bowl containg the water and dry ice. After a few trys a bubble formed on the bowl causing the bubble to expand. We learned after that the attractrion that holds the molecules together of CO2  double bonds. 

Link:http://chemed.chem.purdue.edu/genchem/topicreview/bp/intermol/intermol.html#force

Electron configuration and flame test

    This week in science we learned about electron configurations and electrons in an atom. I found electron configuration very interesting yet easy. As we continued to learn and practice the rules they became easier and easier.

    While learning about electron configuration we learned many rules pertaining to orbitals. The first rule that we learned about orbitals Aufbau principle which stated that the lowest potential energy electron in an atom is found in the 1s sub level and electrons will occupy one orbital only after the previous orbital is completely full.  Next, we learned about Pauli exclusion principle telling us that if two electrons occupy the same orbital, they must have opposite spins. Lastly, we learned Hund's rule that says electrons will pair up in an orbital only when all orbitals in the same sub level have one electron. These rules were fairly easy to learn and made sense to me. Our lab for electron configuration was the flame test lab. In this lab we lit on fire various ions and observed the colors they created. After this experiment we learned that each ion had their own specific color and that this experiment would not be a useful way to detect an individual ion because the colors would mix to form a whole new color. As the picture shows Cu+ glows green when lit on fire. In this experiment as we lit more ions on fire I was surprised to learn all the ions had such varying, vibrant and pale, colors. From Ba+ pale yellow to Li+ hot pink. In this chapter I feel I understand the laws and rules of electron configuration very well. One thing I would be more interested in learning about though would be more of why scientists use the flame test. Including what they discover that has made a difference in our world today.