Periodic Table and Its Trends - PowerPoint - PowerPoint

							Periodic Table and Its Trends
       2A.6 – A.8, and A.10
Characteristics of Elements

                         atomic #
            19



          K
         Potassium
                      element symbol



                       element name


                       atomic mass
          39.098
Atomic Number
 The number
 of PROTONS
 in the
 nucleus of
 the atom of
 that
 ELEMENT.
         Nucleus
 The nucleus of an Atom
 is composed of
 PROTONS & NEUTRONS.
 Positive Charge
 Occupies a very small
  portion of the volume of
  the atom.
 VERY   HIGH DENSITY
Atomic Mass Number
 Most  of the MASS
  is concentrated in
  it’s nucleus.
 Therefore, the
  total number of
  protons and
  neutrons is the
  MASS NUMBER.
         Isotopes
 Atoms that have the same
  number of PROTONS but different
  numbers of NEUTRONS
 They are however chemically
  alike, because they have the
  same numbers of PROTONS and
  ELECTRONS
 These subatomic particles
  (protons and electrons) are
  responsible for the elements
  behavior.
                  Isotopic Notation
 • There are two ways to represent elements:
  • Symbol Form:
mass number         #
  atomic #
   (# of   p +)
                    #   X    element
                             symbol

                        OR    mass number   #
                                                X   element
                                                    symbol
   • Shorthand Form:
  name of element followed by atomic mass
 number.     • Ex... Aluminum - 27
                     Nitrogen - 14
                      Carbon - 14
 • You can find mass #, atomic #, # of n0, and #
 of e- with either notation!
Average Atomic Mass
 Is the weighted average of the
  isotopes of that element. The
  weighted average reflects both
  the mass and the relative
  abundance of the isotopes as they
  occur in nature.
 This is why there are decimals in
  the average atomic mass i. e.
  molar mass.
    PERIODIC LAW
When the elements are
arranged in order of
increasing atomic #: there
is a periodic repetition of
their physical and chemical
properties
PERIODIC TABLE
A  column of elements =
  GROUP
 Arranged according to
  SIMILARITIES in their
  properties
 A row of elements =
  PERIOD
Columns (Vertical)

   Called Groups or Families
   Eight main Columns
   Elements within a Family are
    similar but not identical in
    properties
    – Same # of valence electrons
    – All similar in chemical reactivity
    – All similar in physical appearance
Rows (Horizontal)

 Also called Periods
 Determines the # of energy
  levels
 Elements in a period – not alike
  in properties but pattern exists.
 First elements in a Period –
  VERY ACTIVE SOLIDS
 Last element in a Period –
  Always very Inactive Gas
FAMILIES
 ALKALI      METALS
 – Group I – 1 valence electron +1
 – Most Active metals
 – Ex. Lithium, Sodium, Potassium
 – Soft, shiny metals low melting points, good
   conductors of heat and electricity
 – React vigorously with water
 – React rapidly with O2
 ALKALINE EARTH
 METALS
–Group II – 2 valence
 electrons +2
–Second most reactive metals
–Examples: Beryllium,
 Magnesium, Calcium
–Gray-White luster, Harder than
 alkali metals
–Less reactive; Reacts with air
Rare-Earth Elements
 –So similar that they belong in
  same square of periodic table
 –Lanthanide Series
  Soft,malleable metals
  High luster & conductivity

 –Actinide Series
  Radioactive

  Allare synthesized except for
   three elements.
Noble Gases (Inert)

 –Group VIII A
 –Outermost energy level
  is full.
 –Stable: Non-Reactive
 –Ex: Helium, Neon,
  Argon, Krypton, Xenon,
  Radon
FAMILIES
 Halogen        Family
 – Group VII A
 – 7 valence electrons
      (-1) charge
 – Most reactive of non-metals
 – React with metals to form SALTS
 – Example: Fluorine: most reactive of
   halogens, Chlorine, Bromine, Iodine
Transition Metals
–Properties similar to one
 another, but do not fit any
 other family
–Less active than alkali or
 alkaline earth metals
–Form compounds that are
 brightly colored
–Example: Iron, Cobalt,
 Nickel, Copper, Gold, Silver
FAMILIES
  Boron   Family
  –Group III A
  –(+3) charge
  Carbon   Family
  –Group IV A
  –(-4) or (+4) charge
  Nitrogen   Family
  –Group VA
  –(-3) charge
Oxygen Family
–Group VI A
–(-2) charge
–Contains non-metals O
 and S
–Contains metalloids:
 Selenium, Tellurium
–Contains metal: Polonium
 (Radioactive)
  The Periodic Table
Part II—Periodic Trends
        Unit 2A.9
The Periodic Law

 When elements are arranged in
 order of increasing atomic
 number, there is a repeating
 pattern of their chemical and
 physical properties
Example of The Periodic
         Law
Periodic Trends

 • Atomic Radii
 • Electronegativity

 •Shielding Effect

 •Ionization Energy

 •Metallic vs. Non-metallic
    Character
            Periodic Table Trends
•   Atomic Radii: one-half of the distance
    between the nuclei of two like atoms in a
    diatomic molecule
•   Increases as you move down a group
      •   Outer e- are farther from the nucleus as you go
          down the group; more energy levels
•   Decreases as you move across a period (left
    --> right)
      •   Increase in nuclear charge while shielding
          effect remains constant
          Periodic Table Trends
•   Electronegativity: the ability of an atom to
    attract electrons to itself when chemically
    combined with atoms of other elements
•   Electronegativity values have been calculated
    (Pauling electronegative scale) F = 4.0, Cs = 0.7

•   Decreases as you move down a group
•   Increases as you move across a period (left -
    -> right)
Periodic Table Trends

   Shielding effect- the decrease in
    attraction between an electron and the
    nucleus in any atom with more than
    one electron shell
   Increases as you move down a group
   Remains the same as you move across
    a period
Periodic Table Trends

   Ionization Energy- the energy
    necessary to remove an electron from
    the outermost orbital of a neutral
    atom
   Decreases as you move down a group
   Increases as you move across a period
           Periodic Table Trends
•   Metallic Character: the ability of an atom
    to loose electrons
      •   Increases as you move down a group
      •   Decreases as you move across a period (left --
          > right)

•   Non-metallic Character: the ability of an
    atom to gain electrons
      •   Decreases as you move down a group
      •   Increases as you move across a period (left -->
          right)
2A.1 – A.2
    &
  2A.4
Aproperty that can be observed or
measured without changing the identity of
the sample of matter.
 – Color, size, shape, density, odor, ductility,
   malleability, luster, melting point, boiling
   point, state of matter, etc.
A change in matter in which the identity
of the material involved does not change
 – The material remains the same, although its
   form appears to have changed
 – Melting, boiling, bending, etc.
Aproperty that can only be observed or
measured by changing the identity of the
sample of matter.
 – Chemical reactivity
Asubstance changes into one or more
new substances
 – A chemical reaction takes place
 – Burning or rusting
 – Can often be detected by a permanent color
                         Allowing the copper to react with
Bending does not alter
 the chemical identity   nitric acid does alter the chemical
                                       identity
                         Cu + HNO3  H2 + Cu(NO3)2
 The physical and
 chemical
 properties of
 different
 substances
 influence the
 applications for
 which they are
 used.
 We  are going to start looking at ways to
  classify the elements of the periodic
  table.
 The two major classes of the elements
  are metals and nonmetals.
 Metals are to the left of the stair step
  (SS) on the periodic table while
  nonmetals are to the right of the SS.
To the left of the SS
Elements form positive ions
 (cations)
Of 115 known elements, 88 are
 metals
Elements that have a high luster
 and high electrical conductivity
To  the right of the SS
Elements form negative ions
 (anions)
Tend to be brittle solids or gases
 at room temperature
 – Low densities/melting points
These  substances have properties
 similar to those of metals and
 nonmetals
 –They exhibit both properties
Border  the SS
Elements form negative or
 positive ions
 Each  element is composed of atoms
 Gold atoms differ from sulfur atoms in
  the number of protons in the nucleus.
                                   Clockwise
                                    from the
                                    top: sulfur,
                                    antimony,
                                    iodine,
                                    phosphorus,
                                    copper, and
                                    bismuth
Intensive vs. Extensive
Properties
Intensive   Properties
 –Do NOT depend on the amount
  of substance
 –Examples: Density, color,
  melting point, phase, ductility,
  etc.
Extensive   Properties