Wednesday October 30th, 2013

Today in class: 7th grade: Allclasses finished up their virtual microscope lab and then helped others who were not quite done. Students were reminded that I hold working lunches every day and if they did not get done and do not understand something they should go get their lunches and come in and ask questions. There is always a core group of students available for help and camaraderie. Students were given 15 minutes to use the computers and search for information on their science fair or research topics.

We will begin our microscope lab tomorrow by practicing making different types of slides and viewing them under the microscope.

8th grade classes: Today we continued our discussion of the atom and the periodic table of ELEMENTS. I defined an element as a pure substance formed only of atoms and can be found on the Periodic table. I used examples of pure substances versus alloys and mixtures. Students also got a brief history lesson about goldminers and economic strategies of mine owners. They also learned where the thumbs up symbol came from.

Since there seemed to be much more comprehension, we branched out our discussion to include What defines a period on the table and what are groups or families. Check out this link: Periodic Table made simple. Imagine rows on the periodic table as sentences in a book. Every time you come to the end of a row, you have reached the end of a sentence. The end of the sentence is a period. There are seven (7) periods on the periodic table. Every element in a period has the same number of shells within the electron cloud. There can only be a MAXIMUM of 7 shells. I used the analogy of a town they might be planning and they place all the important buildings- police, fire, city hall in the center along with all the neutral buildings such as movie theaters, grocery stores and malls, in the center. This represent the nucleus with the protons (+), neutrons (~). The different shells represent streets in their town all circular. The PERIOD tells them how many streets their town will have.

I then presented the formula 2n². This tells them the MAXIMUM electron capacity at any given shell. For example, the first shell would be 2(1)², meaning there can be a maximum umber of 2 electrons on the first shell, or following our analogy, 2 houses on the first street. THAT DOES NOT MEAN THERE ARE 2 ELECTRONS THERE Automatically. Lets look at Hydrogen for example: . Hydrogen only has one electron so it only has one "renter"to move into one house. There is still one open house in Hydrogen's Valence shell. Valence, meaning the outmost shell of any given atom. This is the most important shell since it is the one that determines what elements can bond with. We also said that all atoms like to be stable and there fore try to fill all their inner shells before moving to the next one.

We ended the discussion with groups, but didn't get to cover it before the bell rang.