Subatomic Particles, Atomic Number and Atomic Mass

Subatomic particles Actual e- -1 p+ +1 no mass (g) Relative mass Name Symbol Charge Electron e- -1 1/1840 9.11 x 10-28 Proton p+ +1 1 1.67 x 10-24 Neutron no 1 1.67 x 10-24 http://www.unit5.org/christjs/site%20map.htm

Structure of the Atom There are two regions: 1. The Nucleus: With protons and neutrons Positive charge Almost all the mass 2. Electron cloud Most of the volume of an atom The region where the electron can be found http://www.unit5.org/christjs/site%20map.htm

If the atom was the size of a stadium, http://www.andrew.cmu.edu/user/jgrao/Manchester%20United/giant%20stadium.jpg If the atom was the size of a stadium, the nucleus would be the size of: a marble. http://www.akronmarbles.com/marble-frag-2.jpg

Symbols Contain the symbol of the element, the mass number and the atomic number X Mass number Atomic # protons + # neutrons mass number # protons http://www.unit5.org/christjs/site%20map.htm

F Symbols 19 9 Find the number of protons number of neutrons http://chemistry.beloit.edu/Stars/EMSpectrum/fluorine.gif Symbols Find the number of protons number of neutrons number of electrons Atomic number Mass number = 9 + F 19 9 = 10 = 9 = 9 = 19 http://www.unit5.org/christjs/site%20map.htm

Br Symbols 80 35 Find the number of protons number of neutrons number of electrons Atomic number Mass number = 35 = 45 = 35 Br 80 35 = 35 = 80 http://www.unit5.org/christjs/site%20map.htm

Na Symbols 23 11 Find the 1+ number of protons number of neutrons number of electrons Atomic number Mass number = 11 Na = 12 23 1+ = 10 11 = 11 = 23 Sodium ion http://www.unit5.org/christjs/site%20map.htm

http://www. webelements. com/webelements/elements/media/nearingzero/Na http://www.webelements.com/webelements/elements/media/nearingzero/Na.gif

Symbols If a neutral atom of an element has 78 electrons and 117 neutrons what is the Number of protons Atomic number Mass number Complete symbol http://www.findajeweler.com/fashion_trends/2004/July/images/pt_sample.gif http://www.radiochemistry.org/periodictable/elements/images/78.gif

http://discover.edventures.com/images/termlib/i/isotope/support.gif

http://www.unit5.org/christjs/site%20map.htm

X Mass number Atomic # protons + # neutrons mass number # protons http://www.unit5.org/christjs/site%20map.htm X Mass number Atomic # protons + # neutrons mass number # protons

Isotopes Atoms of the same element can have different numbers of neutrons This gives them different mass numbers. They have the same atomic numbers. They look, act and react the same. C-12 vs. C-14

Naming Isotopes Put the mass number after the name of the element Examples: Carbon-12 and Carbon-14 Uranium-235 and Uranium-238

Which isotopes are represented in this sketch? http://discover.edventures.com/images/termlib/i/isotope/support.gif

Calculations of Average Atomic Mass Why is the mass number on a periodic table never a nice whole number?

Mass Number vs AverageAtomic Mass The Mass Number is specific to one isotope. The Average Atomic Mass is the calculated based on the abundance of each naturally occurring isotope of that element. The Average Atomic Mass is shown on Periodic Tables. It is the most accurate number that should be used in calculations.

Average Atomic Mass How heavy is an atom of oxygen? There are different kinds of oxygen atoms. oxygen-16, oxygen-17 and oxygen-18 We are more concerned with average atomic mass, based on the abundance of each element in nature. We don’t use grams because the numbers would be too small. California WEB http://www.unit5.org/christjs/site%20map.htm

Atomic Mass Unit (amu or u) This unit is used instead of grams. http://www.unit5.org/christjs/site%20map.htm Atomic Mass Unit (amu or u) This unit is used instead of grams. It is 1/12 of the mass of a carbon-12 atom.

Calculating averages You have five rocks, four with a mass of 50 g, and one with a mass of 60 g. What is the average mass of the rocks? California WEB http://www.unit5.org/christjs/site%20map.htm

Calculating averages Total mass = (4 x 50) + (1 x 60) = 260 g Average mass = (4 x 50) + (1 x 60) = 260 g 5 5 Average mass = 4 x 50 + 1 x 60 = 260 g 5 5 5 Calculating averages California WEB http://www.unit5.org/christjs/site%20map.htm

Average mass = (4/5)50 + (1/5)60 = 260 g 80% of the rocks weigh 50 grams 20% of the rocks weigh 60 grams We calculate atomic mass the same way. http://www.unit5.org/christjs/site%20map.htm

Sample Problem Calculate the average atomic mass of copper if copper has two isotopes. 69.1% has a mass of 62.93 u and the rest has a mass of 64.93 u. California WEB http://www.unit5.org/christjs/site%20map.htm

http://www.unit5.org/christjs/site%20map.htm Average Atomic Mass Calculate the average atomic mass of copper if copper has two isotopes. 69.1% has a mass of 62.93 u and the rest has a mass of 64.93 u. Isotope Percent Abundance Mass Cu-63 69.1 62.93 43.48463 Cu-65 30.9 64.93 20.06337 63.548 u Cu 29 63.548

Radioisotopes

Radioactive: Radioisotope: Capable of spontaneously emitting radiation in the form of particles and/or gamma rays Radioisotope: A radioactive isotope of an element that occurs naturally or is produced artificially.

Radioisotopes Many elements have one or more isotopes that are unstable. Atoms of unstable isotopes decay, emitting radiation as their nucleus changes. The changes can happen quickly or slowly, depending on the isotope. Radiation emitted can be harmless or very dangerous to living cells.

Applications of Nuclear Science Anthropology: Radiology: Nuclear Reactors: http://www.johnharveyphoto.com/RoadTrip/NuclearReactor.jpg http://blogs.warwick.ac.uk/images/flingard/2004/11/08/carbon_dating.jpg http://mednews.stanford.edu/story_images/radiology-xray-051805.jpg

                                                                                                                                                 http://static.howstuffworks.com/gif/carbon-14.gif

http://www.unit5.org/christjs/site%20map.htm

Homework “Isotope Exercise” worksheet Read pages 34-35 of your textbook Prepare a concept map of the key issues related to nuclear power and nuclear waste.

Concept Map Key Features: Contains key ideas Shows relationships Benefits: Helps you organize your thoughts Increases understanding and retention of information Great study tool

http://www.cotf.edu/ete/images/misc/ps1.gif

http://upload. wikimedia. org/wikipedia/en/thumb/3/3a/Conceptmap http://upload.wikimedia.org/wikipedia/en/thumb/3/3a/Conceptmap.gif/450px-Conceptmap.gif

http://library.humboldt.edu/infoservices/Comm280/Concept-Map.jpg

http://www.accessexcellence.org/AE/AEPC/WWC/1995/concept-map-1.gif

Final Notes… You concept map is an INDIVIDUAL activity. Each map should be original and significantly different from all others. Personalize it the way that you want. Your map will be your reference notes. Please do not computerize your map. This is too time consuming without the right software!

Main Source for Slides: http://www.unit5.org/christjs/site%20map.htm