Each element is unique due to its atomic structure. Atoms consist of protons and neutrons located in the nucleus, and electrons outside the nucleus. The number of protons determines the element, while the total of protons and neutrons is the mass number. Isotopes are atoms of the same element with different numbers of neutrons.

1. Particles in the Atom Each element is chemically unique. To understand why they are unique, you need to know the structure of the atom (the smallest particle of an element) and the characteristics of its components .

2. Particles in the Atom Electrons (-) charge no mass located outside the nucleus Protons (+) charge 1 amu located inside the nucleus Neutrons no charge 1 amu located inside the nucleus

3. Structure of the Atom There are two regions The nucleus With protons and neutrons Positive charge Almost all the mass Electron cloud Most of the volume of an atom The region where the electron can be found

4. YOU NEED TO HAVE A COPY OF YOUR PHYSICAL SCIENCE REFERENCE SHEETS READILY AVAILABLE FOR THIS WORK. ONLY USE THE NORTH CAROLINA PHYSICAL SCIENCE REFERENCE SHEETS. PRACTICE USING THIS ESSENTIAL TOOL. IT IS THE EXACT SAME SET OF REFERENCE TABLES YOU WILL USE ON YOUR EOC. IMPORTANT!!! http://www.dpi.state.nc.us/docs/accountability/testing/eoc/PhysicalScience/physicalsciencereferencetable.pdf

5. Counting the Atomic Pieces Atomic Number = number of protons # of protons determines kind of atom number of electrons in a neutral atom Mass Number = the number of protons + neutrons Lets do some math… Mass number – atomic number = neutrons. (protons and neutrons) – protons = California WEB Find the periodic table in your reference sheet Look for Fluorine, element 9. neutrons ?????? F 19 9

6. Symbols Contain the symbol of the element, the mass number and the atomic number. X Mass number Atomic number

7. Symbols Find the number of protons number of neutrons number of electrons Atomic number Mass number = 9 = 10 = 9 = 9 = 19 F 19 9 +

8. Symbols Find the number of protons number of neutrons number of electrons Atomic number Mass number Na 23 11 Sodium atom = 11 = 12 = 11 = 11 = 23

9. Symbols If an element has an atomic number of 23 and a mass number of 51 what is the number of protons number of neutrons number of electrons Complete symbol = 23 = 28 = 23 V 51 23

10. Symbols If an element has 60 protons and 84 neutrons what is the Atomic number Mass number number of electrons Complete symbol = 60 = 144 = 60 Nd 144 60

11. Symbols If a neutral atom of an element has 78 electrons and 117 neutrons what is the Atomic number Mass number number of protons Complete symbol = 78 = 195 = 78 Pt 195 78

12. Symbols Find the number of protons number of neutrons number of electrons Atomic number Mass number Na 23 11 1+ Sodium ion = 11 = 12 = 10 = 11 = 23

13. Symbols if an element has an atomic number of 34 and a mass number of 78 what is the number of protons number of neutrons number of electrons Complete symbol Name

14. Symbols if an element has 91 protons and 140 neutrons what is the Atomic number Mass number number of electrons Complete symbol Name

15. http://www.quia.com/cb/36842.html ATOMIC PARTICLES QUIZ Click on the link below and quiz yourself in a jeopardy atomic structure quiz.

16. Mass number versus Atomic Mass Notice mass # is just the atomic mass rounded off. Atomic mass is the mass (in a unit called amu’s) of a single atom . Mass number is the atomic mass rounded off, and equals the number of protons and neutrons together. Atomic mass 35 45 35 80 35 Br 18 22 18 40 18 Ar 20 20 20 40 20 Ca e – n 0 p + Mass # Atomic # Ca 40.08 20 Ar 39.948 18 Br 79.904 35 Atomic mass

17. Isotopes Atoms of the same element can have different numbers of neutrons. Different numbers of neutrons mean different masses and thus different mass numbers These elements are called isotopes of that element. Remember Dalton’s Atomic Theory??? One of his 4 tenants was that all atoms of the same element were alike. Ends up , DALTON WAS WRONG! Isotopes of Boron

18. Isotopes are like identical twins. They are almost exactly alike but not quite. For example, below are two forms of carbon. Carbon-12 Carbon-13 Carbon 13 is heavier by one neutron than Carbon-12 = proton = neutron

19. 6 Li 7 Li Nucleus Electrons Neutrons 3 Protons 3 Electrons 3 Nucleus Electrons Neutrons 4 Protons 3 Electrons 3 3 p + 3 n 0 2e – 1e – 3 p + 4 n 0 2e – 1e – + + + Nucleus Neutron Proton Lithium-6 Nucleus Neutron Proton Lithium-7 + + +

20. Isotopes Chlorine-37 atomic #: mass #: # of protons: # of electrons: # of neutrons: 17 37 17 17 20 Courtesy Christy Johannesson www.nisd.net/communicationsarts/pages/chem Cl 37 17 37 17 Cl

21. Naming Isotopes Put the mass number after the name of the element. carbon- 12 carbon -14 uranium-235

22. Bohr - Rutherford diagrams Putting all this together, we get B-R diagrams To draw them you must know the # of protons, neutrons, and electrons (2,8,8,2 filling order) Draw protons (p + ), (n 0 ) in circle (i.e. “nucleus”) Draw electrons around in shells Li shorthand 2 p + 2 n 0 He 3 p + 4 n 0 Li Draw Be, B, Al and shorthand diagrams for O, Na 3 p + 4 n 0 2e – 1e –

23. 11 p+ 12 n° 2e – 8e – 1e – Na 8 p+ 8 n° 2e – 6e – O 4 p+ 5 n° Be 5 p+ 6 n° B 13 p+ 14 n° Al

24. Atomic Structure ATOMS Differ by number of protons IONS Differ by number of electrons ISOTOPES Differ by number of neutrons

25. IONS Created when an atom gains or loses one or more electrons It acquires a net electrical charge. Charge of ion= the number of protons - the number of electrons

26. ATOMIC STRUCTURE Yttrium 1- 17 14 6 Element Z M p e n +/- Formula Oxygen 14 25 137 4

27. http://www.colorado.edu/physics/2000/applets/a2.html