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pCHAPTER 3- ATOMS AND THE PERIODIC TABLE

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pCHAPTER 3- ATOMS AND THE PERIODIC TABLE Powered By Docstoc
					ATOMS AND THE PERIODIC
        TABLE
      chapter three
         FOCUS ACTIVITY 1
METAL       USE      PROPERTY
Copper      Money    durable
    ATOMIC THEORY - history
4TH CENTURY            Matter is made of tiny
B.C.                   particles called ATOMS.
              John     ELEMENTS are made
              DALTON   of particles called atoms.
                       ATOMS of the same
                       elements are alike.
                       ATOMS form molecules.
EARLY 1900’s           ELECTRONS orbit like
(1913)                 planets in the solar system.
MID 1900’s   Modern
(after 1925) theory
ATOMIC THEORY - STRUCTURE
   MODEL OF THE ATOM

                                  -
ENERGY          ELECTRON
LEVELS            NUCLEUS

                              +
                 PROTON

                 NEUTRON
                  (NEUTRAL)
    ATOMIC STRUCTURE
    ELECTRON LOCATION
Electrons are found in energy
levels of an atom.

Electrons occupy the lowest
energy level available.

Bohr’s Atom and Energy Levels
Energy Levels are like ladder rungs…




                             GAINING
                             ENERGY




  GOOD           BETTER
Energy Levels
ORBITALS – where the _____ are
located within an energy level.
S orbital
(Like a sphere)
      may contain up
to 2 electrons
      first energy
level is an s orbital
1s and 2s orbitals
 P orbital


(Like a dumbbell)
 may contain up to 2
 electrons
 second energy level
 may contain an s
 orbital and up to 3 p
 orbitals
Orbitals
    _____ electrons are located in the
   outermost energy level of an atom.

They determine the
 chemical properties
 of an element.
3.2 A TOUR OF THE PERIODIC
          TABLE
• Properties of elements change in a regular
  pattern that the table helps to describe.
• Periods –
• Groups(families) -


  Los Alamos National Laboratory:
  Periodic Table
Traditional Periodic Table
A Spiral Vision of the Periodic Table
           of the Elements
The number of protons in an atom
determines an element’s location
on the table.


Los Alamos National Laboratory: Periodic
Table
ATOMIC
NUMBER     6      PROTONS
                  (and ELECTRONS too)
SYMBOL     C
NAME     Carbon
                    PROTONS
MASS     12.001
                  + NEUTRONS
                     MASS #
   1              1



PROTONS AND NEUTRONS
HAVE EQUAL MASS.

ELECTRONS ARE TINY – 1800
EQUAL ONE PROTON.
    1800          1
MASS                35 Cl
ATOMIC NUMBER       17

protons _?_ electrons _?_
neutrons _?_
 IONS are atoms that have lost or
 gained an ___.
• ELECTRON GAINED =   ELECTRON LOST =
  NEGATIVE CHARGE     POSITIVE CHARGE
         (-)                  (+)
      Electron
      transfer



Na+
                 Cl
      TWO KINDS OF IONS:

A (+) CHARGED
 ION IS A ____.   EXAMPLES:
                  • LITHIUM
                  • FLUORIDE
A (-) CHARGED
 ION IS AN ___.
 The atoms of an element always
have the same number of protons.
              BUT…..
The atoms of an element may have
  different numbers of neutrons.
       This is an ISOTOPE!
Two carbon ISOTOPES:
CARBON 12 = 6 protons and 6 neutrons
CARBON 14 = 6 protons and 8 neutrons
The AVERAGE MASS of an ATOM
     • Why is the mass number not an even
       number?
       – Atoms of the same element exist with
         different numbers of neutrons.
       – This makes the mass of different atoms of
         the same element different.
       – The average mass is a weighted number so
         that more common isotopes have a greater
         affect on the average than rare isotopes.
     • What is an amu?
       – It is an “atomic mass unit”.
       – An amu is equivalent to the mass of 1/12 of
         a carbon-12 atom.
3.3 FAMILIES OF ELEMENTS:
• HAVE THE SAME VALENCE NUMBER.
• HAVE SIMILAR CHEMICAL AND
  PHYSICAL PROPERTIES.
• A COLUMN OF ELEMENTS IS A
  FAMILY.
   TWO MAJOR DIVISIONS
• METALS     • NONMETALS
        GROUP ONE:
       ALKALI METALS
• VERY REACTIVE
• ONE VALENCE
  ELECTRON
      GROUP TWO:
 ALKALINE EARTH METALS
• TWO VALENCE ELECTRONS
        GROUP 3-12:
     TRANSITION METALS
• MANY COMMON METALS
• NOT AS REACTIVE AS OTHER
  METALS
                 GROUP 17:
• VERY REACTIVE
                 HALOGENS
• FORM SALTS WITH ALKALI METALS
• 7 VALANCE ELECTRONS
        GROUP 18:
       NOBLE GASES
• INERT / UNREACTIVE
• EIGHT VALENCE ELECTRONS
SYNTHETIC ELEMENTS
 • They are man-made and radioactive.
 • They include all elements above #92, plus
   #43 and #61.
       SEMICONDUCTORS
         (METALOIDS).
The elements that are between the metals and
 nonmetals are known as:
  SEMICONDUCTORS (METALOIDS)
  They may exhibit metallic and nonmetallic
   properties.
                     B
                           Si
                          Ge    As
3.4 USING MOLES TO COUNT ATOMS
• Some counting units:
  –   Reams of paper
  –   Dozens of eggs
  –   Atomic mass units of protons and neutrons
  –   Moles of atoms
• A mole is the SI unit that describes the amount of a
  substance.
• Avogadro’s constant is the number of particles in
  one mole which = 6.022 x1023
• molar mass is the mass in grams of one mol of a
  substance…it is equal to the average atomic number
  of an atom.
                 Chapter 3
            Studying for the Test

•   Vocabulary
•   Parts of an atom
•   History
•   Element families
•   Using the periodic table
•   Metal vs. nonmetal

				
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