Tuesday, December 4, 2012

Periodicity


Objectives: to learn about atomic structure:   1) how the elements are organized

                                                                        2) basic atomic structure

                                                                        3) how the structure of atoms differ

Periodic Table

·         Symbols & elements

·         Groups and periods of elements

·         Metals vs. non-metals

Organization of the Periodic Table

·         Groups of elements (families)

·         Periods of elements (series)

Groups of Elements (families)

·         Column of elements on the tables

·         Members have similar physical & chemical properties

Periods of Elements (series)

·         Rows of elements

·         Members have electrons in the same valence shell

-Metals

·         Good conductors of heat & electricity

·         Ductile- can be drawn into wires

·         Malleable-pounded into shapes

·         Lustrous- reflect light

·         Form “+” ions

·         Contain a metallic bond

·         “sea” of de-localized electrons

·         Examples: Ag, Fe, Hg, Ti, Pb

-Non-metals

·         Poor conductors “insulators”

·         Brittle

·         Dull

·         Form “-“ ions

·         Examples: Se, P, C, I, Br

-Metalloids

·         Have properties of both metals and non-metals

·         Semi-conductors

·         Examples: B, Te, Ge, As, Si

Relation to the Periodic Table

·         Atomic number (Z)

·         Number of protons in an atom whole number on the periodic table

·         Mass number (Mn)

o   Mn= P+ + N°

o   Integer closest to atomic mass is protons + neutrons

·         Atomic Mass

o   Relative mass of the atom (the other number on the periodic table)

·         Isotopes

o   Atom of same elements with a different number of neutrons in a nucleus (2 or more atoms)

§  Protium: Hydrogen-1

§  Daterium: Hydrogen-2

§  Tritium: Hydrogen- 3

o   The number stands for the mass number of the isotopes

Isotopes
Protons
Neutrons
Electrons
Hydrogen-1
1
0
1
Hydrogen-2
1
1
1
Hydrogen-3
1
2
1

 

Assuming neutral atoms protons=electrons

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