The Periodic Table of Elements

1. The Periodic Table of Elements

2. The Periodic Table • Something periodic occurs at regular or at least generally predictable intervals • Periodic Table of Elements – a table of the elements, arranged by atomic number, that shows the patterns in their properties • The Periodic Table can be used to identify metals, nonmetals and metalloids. These elements are divided by a zigzag line. Can you think of anything that is periodic?

3. Element • A pure substance made up of one kind of atom that cannot be broken down into simpler substances by physical or chemical means • 90 occur naturally on earth • 25 were synthesized (made) by scientists Element Song http://www.privatehand.com/flash/elements.html

4. Dmitri Mendeleev • In the 1860’s he devised a periodic table where the elements were ordered by their atomic masses • He did this by grouping elements together according to their similarities and chemical reactivity. Image taken from: http://jscms.jrn.columbia.edu/cns/2006-04-18/fido-luxuriantflowinghair/mendeleev/

5. Mendeleev’s Published Periodic Table of Elements Why do you think there are question marks here? Image taken from: http://www.chemsoc.org/networks/learnnet/periodictable/post16/develop/mendeleev.htm

6. Mendeleev’s Predictions • Although Mendeleev’s Periodic Table of Elements had missing elements or “gaps,” he was able to predict the characteristics of these missing elements. “Ekasilicon” Germanium Notice how Mendeleev’s predictions (orange column) were very accurate when compared to Germanium’s actual characteristics (green column)

7. Henry Moseley • In 1914, his work led to the one and only revision of the periodic table by rearranging the elements by their atomic numbers • He concluded that the number of protons in an atom is its atomic number. Image taken from: http://dewey.library.upenn.edu/sceti/smith/

8. 3 Classes of Elements Using this as a guide, color code your periodic table to show the three classes. Start by highlighting the “zig-zag.”

9. Metals Location • Found on the left of the zigzag line on the periodic table (exception  Hydrogen) Chemical Properties • Have few electrons in their outer energy level, thus lose electrons easily Physical Properties • ductile, good conductors, malleable, shiny, most are solid @ room temperature Image taken from: http://chemistry.about.com/od/periodictableelements/ig/Element-Photo-Gallery.--98/Sodium.htm What metal is not a solid @ room temperature?

10. - + + - - + + + + + - - - - + - - + + + + + - - + + - - - - Atoms with Few Electrons in their Outer Energy Level Notice: only 1 electron in outer level Notice: only 2 electrons in outer level

11. Non-Metals Location • Nonmetals are found to the right of the zigzag line on the periodic table Chemical Properties • Most have almost full outer energy levels, thus they tend to gain electrons; some have completely full outer level Physical Properties • brittle, dull, poor conductors, most are solid, but some are gas at room temperature & do make good insulators Image taken from: http://nobel.scas.bcit.ca/resource/ptable/cl.htm Image taken from: https://www.dmr.nd.gov/ndgs/rockandmineral/sulfur.asp

12. - + + + + - - - - - - + + + + - - + + + + + + + - + + - - + + - - - - - - - Atoms with Full or Almost Full Outer Energy Level Notice: 2 electrons in outer level – FULL Notice: 6 electrons in outer level – almost full Notice: 7 electrons in outer level – almost full

13. Metalloids Location • Border the zigzag line on the periodic table Chemical Properties • Most atoms have ½ (≈) complete set of electrons in outer level Physical Properties • some properties of both metals and non-metals; not effective conductors; many are ductile & malleable Image taken from: http://library.thinkquest.org/C0113863/bios.shtml Image taken from: http://library.thinkquest.org/C0113863/bios.shtml

14. - - - + - - - - + + + + + + + - + + + + + - + - - - - + + + + + - - - - - - Atoms with ½ (≈) Complete Outer Energy Level Notice: only 4 electrons in outer level Notice: only 3 electrons in outer level

15. Important Features of the Periodic Table:Period (Row) • each horizontal row of elements on the periodic table How many periods (rows) are on the Periodic Table Of Elements? FROM LEFT TO RIGHT OR RIGHT TO LEFT

16. Period (Row) Properties • Seven periods on a periodic table (numbered from the top down) • Atomic numbers and atomic masses increase as you move from the left to the right in a period • Elements found in the same periods have dissimilar properties and behaviors • All atoms of the elements in the same period have the same number of energy levels • Example • Period 1 = 1 energy level • Period 2 = 2 energy levels • Period 3 = 3 energy levels

17. - - - + + + + - - - - - + - - + + + + + + + + + + + + + + - + - - - - - - - + + + - + + + - + - + + + - - - + + + - + + - - - - + + - - - - - - - - Examples of Period (Row) elements having the same number of energy levels in their atoms In what period (row) do you think these atoms reside? In what period (row) do you think these atoms reside?

18. Important Features of the Periodic Table: Group (Family) • each column of elements on the periodic table How many groups (families) are on the Periodic Table Of Elements? FROM TOP TO BOTTOM OR BOTTOM TO THE TOP

19. Group (Family) Properties • Eighteen groups on the periodic table (numbered from left to right) • Atomic numbers and atomic masses increase as you move from the top down in a group (family) • Atoms of elements in the same group have the same number of electrons in the outer energy levels of their atoms (known as valence electrons) • Exceptions: • Transition elements (3-12) • Hydrogen (could be 1 or 17) • Helium (actually has 2 valence electrons) • Elements in groups usually have similar physical and chemical properties

20. 1 H 1.008 3 Li 6.941 + 11 Na 22.990 + + - 19 K 39.098 - - + 37 Rb 85.468 - - + + + + 55 Cs 132.905 + - - + + 87 Fr (223) - - - - Examples of Group Elements with the same # of valence electrons How many electrons do each of these atoms have in their outer orbital/level? What group (family) do these elements reside in?

21. Group (Family) Names Alkali Metals Alkaline Earth Metals Noble Gases Boron Group Nitrogen Group Carbon Group Oxygen Group Halogens Transition Metals

22. Reactivity • Reactivity depends on the number of valence electrons • Since groups have the same number of valence electrons, groups have similar reactivity

23. Reactivity • Reactivity describes how easily a substance reacts with another element or compound. Photo: www.chemicum.com

24. Reactivity • Valence electrons determine an element’s reactivity—a chemical property Photo: www.sciencephoto.com

25. Reactivity • Generally, elements in the same group (except for Groups 3-12) have similar chemical properties • Ex. Flammability & combustibility Photo: www.chemistryland.com

26. Using the Periodic Table • The boxes that make up the periodic table contain a significant amount of information. To understand this information, it is necessary to refer to the periodic table’s key(s) Atomic Number (Number of protons) Element Symbol (Written with a capital letter or a capital followed by a lower case if two letters ) Element Name Atomic Mass (Rounded to a whole number, equals the number of protons and neutrons) What is Oxygen’s physical state of matter? Which class does Oxygen fall into?