1. Wednesday!!!!! 9/28/11 Bell Ringer 1)Get out your chapter notes and answer the following question: 1)Why is the Periodic Table a great resource tool? 2)How many atoms of each element are in the following compound? 1)NaCl 2)H 2 O 3)Ca 3 (PO 4 ) 2 Schedule 1.Bell Ringer 2.PT Notes 3.Practice Problems HOMEWORK: Finish Practice Problems & Study elements!! PAP Chemistry Teachers open the door, but you must enter by yourself. I CAN……identify an unknown solution using physical properties.

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 H 2, N 2, O 2, F 2, Cl 2, He 2, 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 – CO 2, CH 4, C 4 H 10, SO 2

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 KrF 2, 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 H 2, N 2, O 2, F 2, Cl 2, Br 2 and I 2

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 H 2 O Two hydrogen atoms bonded to one oxygen atom *Remember, all molecules are compounds but not all compounds are molecules. (ex: PO 4 -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(NO 3 ) 2

16. Chemical Formulas Abbreviation for compound Symbols and subscripts How many atoms of each elements are in the following compounds? KBr PbCl 3 CaCO 3 Mg(OH) 2 H 2 SO 4 Ca(NO 3 ) 2