Wednesday!!!!!9/28/11

Bell Ringer1) 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) NaCl2) H2O

3) Ca3(PO4)2

Schedule1. 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.

Elements & Compounds

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

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

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

Metals, Non Metals & Metalloids

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

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

Metalloids

• Have properties of both metals and nonmetals

• B, Si, As, Ge, Sb, Te, Po• B, Si and Ge are used in semi-conductors

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.

Diatomics

• Contain two atoms (can never exist alone bc too reactive)

• Seven diatomics

• H2, N2, O2, F2, Cl2, Br2 and I2

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

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)

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

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