Wednesday!!!!! 9/28/11

1. Wednesday!!!!!9/28/11 Bell Ringer Schedule PAP Chemistry • Bell Ringer • PT Notes • Practice Problems HOMEWORK: Finish Practice Problems & Study elements!! I CAN……identify an unknown solution using physical properties. Teachers open the door, but you must enter by yourself.  • Get out your chapter notes and answer the following question: • Why is the Periodic Table a great resource tool? • How many atoms of each element are in the following compound? • NaCl • H2O • Ca3(PO4)2

2. Elements & Compounds

3. Elements • Can not be broken down • Building blocks of all substances • Most Pure substances (that are compounds) can be broken down (sugar, salt, water) • Above 92 on periodic table, except plutonium, do not occur naturally • Smallest unit retaining properties of element: atom

4. Elements in Nature • Br and Hg liquid at room temp • 11 are gases • H2, N2, O2, F2, Cl2, He2, Ne, Ar, Kr, Xe, Rn • Rest are solids • Names and Symbols: one or two letters, first letter is always capitalized H = Hydrogen He = Helium Li = Lithium Be = Beryllium

5. Periodic Table • Atomic number: whole number increasing as you move left to right… • Elements arranged with similar chemical properties in columns: Families or groups • Group 1A: alkali metals • Group 2A: alkaline earth metals • Group 3A: Boron Family • Group 4A: Carbon Family • Group 5A: Nitrogen Family (Pnictigens) • Group 6A: Oxygen Family (Chalcogens) • Group 7A: Halogens • Group 8A: Noble Gases • Groups 1- 7A and Noble Gases are referred to as Representative Elements • Middle of table is Transition Elements

6. Metals, Non Metals & Metalloids

7. Metals • Most of P. table • Solids @ room temp • Hg is liquid • Lustrous • Good conductors: heat, electricity • Malleable • Ductile • High mp and density • Ex: Al, Ag, Zn, Sn • Generally combine with non metals to form COMPOUNDS • Alloys are mixtures of metals • HOMOGENEOUS mixtures: brass, bronze, steel, coinage

8. Nonmetals • Nonlustrous • Low mp and densities • Poor conductors of electricity and heat • Br, liquid at room temp • C, P, S, Se, I solid at room temp • Rest of nonmetals are gases at room temp • Carbon (diamond and graphite in nature) • Nonmetals combine with each other to form compounds • CO2, CH4, C4H10, SO2

9. Metalloids • Have properties of both metals and nonmetals • B, Si, As, Ge, Sb, Te, Po • B, Si and Ge are used in semi-conductors

10. Elements in Natural State • Elements exist in mixtures or compounds • Most elements are reactive • Ag, Po and Au can be found in pure form in nature • Nobel gases: Group 8A: non-reactive, for the most part • Krypton forms KrF2, a colorless solid, on reaction with fluorine. • Helium, neon and argon form no known compounds. • Xenon forms a wide range of compounds with oxygen and fluorine.

11. Diatomics • Contain two atoms (can never exist alone bc too reactive) • Seven diatomics • H2, N2, O2, F2, Cl2, Br2 and I2

12. Compounds • Two or more elements • Chemically combined • Definite proportions by mass • Can decompose chemically into simpler substances • Atoms are in whole number ratios • NO FRACTIONS

13. Molecules • Smallest uncharged unit of a compound • Union of two or more atoms • H2O • Two hydrogen atoms bonded to one oxygen atom • *Remember, all molecules are compounds but not all compounds are molecules. (ex: PO4-3)

14. Ions • Positively or negatively charged atom or group of atoms • Cation is positive ion: loss of electron(s) • Anion is negative ion: gain electron(s) • Ionic bond is formed between cation and anion • NaCl, NaOH, Ca(NO3)2

16. Chemical Formulas • Abbreviation for compound • Symbols and subscripts • How many atoms of each elements are in the following compounds? • KBr • PbCl3 • CaCO3 • Mg(OH)2 • H2SO4 • Ca(NO3)2