Atoms_ Bonding and The Periodic Table by yurtgc548

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									Atoms, Bonding and
 The Periodic Table
 Chapter 5,
  Section 1
Pg.’s 176-182
    Remember!!!!
 The nucleus of an atom
  contains protons and
  neutrons and is surrounded
  by electrons in orbit.
 Electrons are in specific
  orbital's, some closer to the
  nucleus than others.
 The electrons that are
  furthest from the nucleus, in
  the highest energy level, are
  valence electrons.
How the Periodic Table Works
 The periodic table reveals the underlying
  atomic structure of atoms, including the
  arrangement of atoms.
 As the atomic number increases, the
  number of electrons also increases.
      Valence Electrons
 The electrons in the highest energy level,
  furthest from the nucleus. (fig. 1, pg. 176)
 Are held most loosely.
 The number of Valence electrons in an atom of
  an element determines many properties of that
  element, including the way in which the atom
  can bond with other atoms.
    Electron Dot Diagrams
 Depicts the number of valence electrons an
  element has. (fig. 2, pg. 177)
 Includes the symbol for the element surrounded
  by dots.
 Each dot stands for one valence electron.
 Atoms of most elements          Valence
  are more stable (less likely Electrons and
  to react) when they have 8
                                  Element
  valence electrons.
                                 Reactivity
 The noble gases all have
  8 valence electrons in
  their outer orbital.
 Some smaller atoms, such
  as Helium, are stable with
  only 2 valence electrons.
                             Chemical
                             Bonds and
                              Stability
 Atoms usually react to become more stable.
 They do this in 2 different ways.
   They increase their number of valence
    electrons to 8.
   They give up their loosely held valence
    electrons.
     Atoms that react like this can become chemically
      combined, creating a chemical bond.
        Chemical Bonds and
          Group Patterns
 The force of attraction that holds 2 atoms
  together as a result of the rearrangement of
  electrons between them is a chemical bond.
  (fig.’s 3 & 4, pg.’s 178 & 179)
 Notice the Valence electron group pattern:
     Group 1 elements have 1 valence electron.
     Group 2 elements have 2 valence electrons.
     Group 13 elements have 3 valence electrons.
     What is the pattern (minus groups 3-12)?
                         Reactivity of
                         Halogens and
                         Alkali Metals
   Group 17, the halogens, need to gain just 1 electron
    to have 8. As a result they react easily with other
    elements whose atoms can give up or share 1
    electron.
   Group 1, the alkali metals, have only 1 valence
    electron. This property makes them very reactive
    because they only need to lose 1 electron to become
    chemically stable.
   Why do Halogens react violently with Alkali metals?
The other Metals???
      The reactivity of metals
       decreases from left to right
       across the periodic table.
      Groups 2-12 have 1, 2, or 3
       valence electrons.
      They react by losing these
       electrons.
      Why do they give up their
       electrons instead of trying
       to gain more?
                The
            Semimetals???
 The semimetals have 3-6 valence
  electrons and can lose or share electrons
  depending on the conditions.
 They can behave as either Metals or
  Nonmetals.
    The other Nonmetals??
 All of the nonmetals have 4 or more
  valence electrons.
 They react by gaining or sharing electrons
  to have a set of 8 valence electrons.
 Why do they gain electrons instead of
  losing them?
    Any Questions???
   Complete your notes, summaries, and
    questions.

								
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