1. The Periodic Table Chemistry Fall 2013

2. Periodic Table  Developed by Dmitri Mendeleev in 1869  Originally ordered by atomic mass  Today ordered by atomic number  Ordered left to right by increasing atomic number Question: How is the periodic table ordered?

3. Element C Carbon 12.01 atomic number average atomic mass Element symbol Element name 66

4. Atomic Mass  Not the same as mass number  Average mass of one atom of the element Question: Why is atomic mass not a simple whole number?

5. AtomAtomic number Mass Number # Protons# Neutrons# Electrons Top Number Protons + Neutrons Same as atomic # Mass #- Protons Same as atomic # (unless ion) Li37343 O -2 8168810 Ca +2 20 4020 18

6. Metal/Semimetal/Nonmetal Metal Semimetal(metalloid) Nonmetal

7. Metals  Thermally/electrically conductive (allows heat and electricity to travel through.  Malleable, ductile  High density  Lustrous (shiny) GalliumGold

8. Nonmetal  Poor conductor of heat and electricity  Brittle  Low density  Dull Iodine Bromine

9. Semimetal  Also known as metalloids  Properties of both metals and nonmetals  Often are semiconductors Silicon Antimony

10. Question: Compare and contrast metals, semimetals, and nonmetals.

11. Organization  Periods: horizontal rows (left and right)  Groups/Families: vertical columns (up and down) Similar chemical properties Similar chemical properties Group # Group name Examples 1 Alkali metals Li, Na, K, Rb 2 Alkaline earth metals Be, Mg, Ca, Sr 3-12 Transition metals Fe, Ni, Zn, Ag 16Chalcogens O, S, Se, Te 17Halogens F, Cl, Br, I 18 Noble gases He, Ne, Ar, Kr Question: What is the significance of being in the same group?

12. Tree Map of Elements.  Elements  Metals Semi-metals Nonmetals  Description Description Description