CH 101 1st Edition Lecture 4 Outline of Last Lecture I Coulomb s Laws of Force and Energy II Attracting and Repelling Charges A High Energy versus Low Energy III Subatomic Particles A Isotopes IV Understanding the Periodic Table Outline of Current Lecture I The Original Theories of the Atom II Memorizing the Periodic Table III Using the Periodic Table to find the Charge a Anion b Cation IV Introduction to Elements and Light Current Lecture I What Atoms tell us II In the early 1900 s there were many theories to what the inside of an atom looked like A popular idea was called the Plum Pudding model by J J Thompson This model showed the atom as a glob of protons and electrons all floating around similar to plums in a pudding Another idea that came later was by a man named Ernest Rutherford who used a gold foil experiment to determine that atoms must have a nucleus made out of protons and neutrons Memorizing the Periodic Table These notes represent a detailed interpretation of the professor s lecture GradeBuddy is best used as a supplement to your own notes not as a substitute There is no easy way to memorize the periodic table of elements they best way is to look at the groups families of atoms and remember the elements that are in that family Start with reviewing the main groups of elements and save the transition metals for last because they are not used as much Another method of memorizing the periodic table is by learning the charge of the elements which will help you remember what group they are in If you look at the main groups columns 1 2 and 13 18 you can determine how many electrons are in the elements outer shell III Using the Periodic Table to find the Charge The columns on the periodic table tell us the charge of the atom because it tells us the amount of electrons on the outer shell Charges are very important when it comes to forming molecules and seeing how an element or a molecule will react with other elements and molecules a Anion An anion is an ion of an element It occurs when the amount of electrons is more than the amount of protons in an atom Anions like F1 are negatively charged and are attracted to cations b Cation A cation is also an ion of an atom and occurs when there are fewer electron than protons in an atom making it positively charged He1 is a cation Determining the electrons for column 1 and 2 is easy because column 1 has 1 electron in the outer orbital and column 2 has 2 However in groups 13 18 you take the group number and subtract 10 to find the number of electrons and then subtract that number from 8 to find the charge This is because the first orbital in an atom holds 2 electrons and the next two holds 8 so if the atom has a total of 16 electrons there will be 6 electrons on its outer shell and the charge would be 2 If the amount of electrons in the outer shell is greater than 4 the atom is negatively charged because the atom wants to gain electrons to fill its outer shell If the atom has less than 4 electrons in the outer shell it is positively charged because it wants to give away its electrons If the atom has 4 electrons it is neutrally charged Ex What is the charge of a common Bromine atom Find Bromine on the periodic table it is in the same column as Fluorine 17 10 7 electrons See that Bromine is in group 17 and therefore has 7 outer shell electrons This also tells us that Bromine is negatively charged because 7 is greater than 4 8 7 1 Subtract 7 from 8 to tell you the charge which is the number of electrons the atom wants to fill its outer shell Br1 Answer Bromine has a charge of negative 1 and is a anion IV Introduction to Elements and Light Dr Petrovich demonstrated how different element will low different colors when charged by touching different containers filled with elements in a gas state with a tesla coil The container is helium turned red neon turned orange krypton turned purple and xenon turned white This represented the different frequencies of the light waves that are shown when the electrons in the atoms start to jump to different energy levels