1. JoAnn Yannazzo, NSHS, FWISD The Periodic Table

2. JoAnn Yannazzo, NSHS, FWISD History Karlsruhe Conference (1860) Held to standardize the atomic and molecular masses Mendeleev (1871) Listed elements in vertical colums Used atomic mass Noticed regular recurrence of their properties www.chemsoc.org

3. JoAnn Yannazzo, NSHS, FWISD History Mendeleev (con’t) Arranged columns so elements with similar properties were side by side Many blank spaces – elements weren’t discovered yet Moseley (1913) Arranged elements by atomic number Mendeleev www.chem.msu

4. JoAnn Yannazzo, NSHS, FWISD http://fathom.lib.uchicago.edu

5. JoAnn Yannazzo, NSHS, FWISD The Modern Periodic Table Arranged in seven horizontal rows in order of increasing atomic number Symbol placed in box Atomic number above symbol Atomic mass and name below the symbol ology.amnh.org

6. JoAnn Yannazzo, NSHS, FWISD The Modern Periodic Table Physical state of element at 25 o C can be in a circle in the upper left corner Horizontal rows called periods Verticle columns called groups Representative elements – groups 1A to 7A and group O ology.amnh.org

7. JoAnn Yannazzo, NSHS, FWISD www.wine1.sb.fsu.edu

8. JoAnn Yannazzo, NSHS, FWISD www.chem.gla.ac.uk Rare Earth Metals

9. JoAnn Yannazzo, NSHS, FWISD Periodic Law When elements are arranged in order of increasing atomic number, there is a periodic pattern in their physical and chemicla properties

10. JoAnn Yannazzo, NSHS, FWISD Electron Configurations and Periodicity Noble gases – elements in which the outermost s and p sublevels are filled. They do not participate in many chemical reactions Representative elements – the outermost s or p sublevels are partially filled. Group # is equal to the # of electrons in the outermost occupied energy level. www.wine1.sb.fsu.edu

11. JoAnn Yannazzo, NSHS, FWISD Electron Configurations and Periodicity Transition Metals – outermost s sublevel and nearby d sublevel contain electrons. These are the Group B elements Inner Transition Metals – outermost s sublevel and nearby f sublevel generally contain electrons Can determine electron configuration from the table Period # = principle energy level www.wine1.sb.fsu.edu

12. JoAnn Yannazzo, NSHS, FWISD Atomic Size Determined using covalent atomic radius (estimated) and measured in nanometers. Group trends Atomic size increases as you move down a group Period trends Atomic size decreases as you go left to right Increase nuclear charge pull electrons closer to the nucleus www.encarta.msn.com

13. JoAnn Yannazzo, NSHS, FWISD Ionic Size Positive Ions Always smaller than the neutral atom Nucleus increases attraction for remaining electrons www.public.asu.edu

14. JoAnn Yannazzo, NSHS, FWISD Ionic Size Negative Ions – Anions Always larger than the original neutral atom Nuclear attraction is less Additional electrons increases repulsive forces between electrons www.public.asu.edu

15. JoAnn Yannazzo, NSHS, FWISD Ionization Energy The energy that is required to overcome the attraction of the nuclear charge and remove an electron from a gaseous atom www.chemmed.chem.purdeu.edu

16. JoAnn Yannazzo, NSHS, FWISD Ionization Energy Group trends First ionization energy decreases as we move down a group Periodic trends First ionization energy increases from left to right www.chemmed.chem.purdeu.edu

17. JoAnn Yannazzo, NSHS, FWISD Electron Affinity The energy change that accompanies the addition of an electron to a gaseous atom Most elements release energy when they gain an electron so most electron affinities are negative www.chemmed.chem.purdeu.edu

18. JoAnn Yannazzo, NSHS, FWISD Electronegativity The tendency for an atom to attract electrons to itself when it is chemically combined with another element Uses Pauling electronegativity scale Increases from left to right – Flourine has the highest score Decreases as you move down a group dl.clacamas.cc.or.us