"The country which is in advance of the rest of the world in chemistry will also be foremost in wealth and in general prosperity." William Ramsay, 1852 to 1916
Updated October 5, 2018
Please make sure you READ everything on this page or you will miss important details. I will archive past weeks Announcements pages for a limited time only under the Trimester 1 tab, if you need to go back to a particular weeks information for any reason.
Week 6 Summary
During the past two weeks, you should have learned in class and read in your text, Dalton's Atomic Theory (1808). As a reminder, the four basic tenets of his theory are as follows:
Recollect that Dalton came from a large line of men of faith who were scientists in Western Europe, and these very men were responsible for many of the foundations of science! The alleged war between science and faith is a relatively new construct, proffered by atheists who believed that as new discoveries were made by way of the scientific method, people would no longer see the need for a Creator.
We briefly discussed the structure of an atom, along with the very experiments carried out by J.J. Thomson - who worked with cathode rays shot through a gas-filled tube (discovering electrons). Remember what this model was called?
Then, we discussed the Rutherford, Marsden & Geiger experiment: these researchers shot positively-charged alpha particles though a thin gold foil, with the expectation that the particles should have passed right through the foil with very minimal deflection (if the Plum Pudding model of the atom were correct). What shocked them was that some particles deflected right back at them. From this deflection, they surmised that there must be a dense, positively-charged nucleus.
Please make sure you remember these experiments - they were pivotal in ascertaining the structure of an atom!
Remember what atomic number (Z) refers to? The atomic number of an element is equal to the number of protons in the nucleus. For neutral atoms, the number of protons equals the number of electrons. The mass number (A) of an element refers to the number of protons and neutrons.
Qualitative and Quantitative Observations Lab
Recollect that the class performed the Quantitative and Qualitative Observations lab on Tuesday. The purpose of this lab was to teach you how to make and record both qualitative ("the copper chloride solution was clear and blue"), and quantitative ("the temperature before adding the aluminum was only 22.5 degrees Celsius") observations. You should have noted that the copper chloride solution did react vigorously with the aluminum foil, in what is called a redox reaction. whereas the copper sulfate solution did not. In class, many of you were able to observe what happens when you add sodium chloride (a chloride ion source) into the copper sulfate beaker. The chloride ions acted as a catalyst that sped up the redox reaction in the copper sulfate beaker. Make sure you complete all the questions on the lab, and complete the lab quiz (linked right).
Next week you will learn how to calculate the average atomic mass for an element. Many students struggled with this idea last year; please take a moment to watch Tyler Dewitt (linked right) provide the how-to of this!
Looking Ahead to Week 7
For this coming week, we are going to look at the periodic table. You should know that the table is arranged according to increasing atomic number (not mass). When Mendeleev published his periodic table in 1869, he arranged the elements in the table according to increasing atomic mass. Our contemporary table (image below) is ordered according to increasing atomic numbers - we have British physicist Henry Moseley to thank for that.
We are a little off of syllabus right now with respect to laboratories, so please plan to carry out the Element Investigation Lab this week. In order to successfully complete this lab, you will need to download The Periodic Table app by The Royal Society to your phone.
If you are in either of my chemistry sections at PEP, please make sure you do the following by:
Tuesday, October 16th
Week 7 Resources/ Assets
Test #1 will be returned on Tuesday, October 16th.