The Periodic Table and Periodic Law

1
The Periodic Table and Periodic Law

• Chapter 6

2
Section 6.1 Development of the Modern Periodic
Table

• Late 1790s- Lavoisier compiled a list of 23
  elements known at the time
• By 1870- 70 known elements
• John Newlands
• Arranged elements by increasing atomic mass
• Noticed properties repeated every eighth element
  (periodic)
• Law of Octaves

3
Dmitri Mendeleev

• Russian
• 1st periodic table
• Organized elements by properties
• Arranged elements by atomic mass
• Predicted existence of several unknown elements
• Element 101 Mendeleevium (Md)

4
(No Transcript)
5
Henry Moseley

• 1913-performs experiments to determine the atomic
  number of the known elements
• Afterwards arranges the elements in the periodic
  table listing them by increasing atomic number
  instead of by mass

6
Periodic Law

• When the elements are arranged in order of
  increasing atomic number, there is a periodic
  repetition of their physical and chemical
  properties

7
The Modern Periodic Table

• Groups- aka families (vertical columns)
• Each group is numbered 1-8 followed by the letter
  A or B
• Representative Elements- designated with an A
  (1A-8A)
• Transition Elements- designated with a B (3B-12B)
• 18 total groups
• elements of any one group have similar physical
  and chemical properties

8

• Periods- horizontal rows
• 7 total periods
• element properties change as you go across each
  row
• the pattern of properties repeats from one period
  to the next

9
Classifying the Elements

• Three main classifications for the elements
• Metals
• Nonmetals
• Metalloids

10
Metals

• Physical Properties
• Luster (shininess)
• Good conductors of heat and electricity
• High density (heavy for their size)
• High melting point
• Ductile (most metals can be drawn out into thin
  wires)
• Malleable (most metals can be hammered into thin
  sheets)
• Chemical Properties
• Easily lose valence electrons
• Corrode easily
• Alkali Metals- group 1A elements (except
  hydrogen)
• Alkaline Earth Metals- group 2A elements

11
Metals Cont.

• Transition Metals
• Group B elements
• Inner Transition Metals
• Lanthanide- used as phosphors (substances that
  emit light when struck by electrons)
• Actinide

12
Nonmetals

• Physical Properties
• No luster (dull appearance)
• Poor conductor of heat and electricity
• Brittle (breaks easily) or gaseous
• Not ductile
• Not malleable
• Low density
• Low melting point
• Bromine is the only nonmetal liquid at room
  temperature
• Chemical Properties
•  Tend to gain valence electrons

13
Nonmetals Cont

• Halogens
• Group 7A
• Extremely Reactive
• Noble Gases
• Group 8A
• Extremely Unreactive

14
Metalloids

• Bordering the stair-step line
• Physical Properties
• Solids
• Can be shiny or dull
• Ductile
• Malleable
• Conduct heat and electricity better than
  nonmetals but not as well as metals

15
(No Transcript)
16
(No Transcript)
17

• Elements in the same group on the periodic table
  have similar chemical properties because they
  have the same valence electron configuration

18
Section 6.3 Periodic Trends

• The electron cloud surrounding the nucleus is
  based on the probability and does not have a
  clearly defined edge
• Atomic size is defined by how closely an atoms
  lies to a neighboring atom

19
Atomic Radii Trend

• Trends within periods
• Generally decreases as you move left-to-right
  across a period (row)
• Trends within groups
• Generally increases as you move down a group

20
Ionic Radius

• An ion is an atom or a bonded group of atoms that
  has a positive or negative charge
• When atoms lose electrons and form positively
  charged ions, they always become smaller
• When atoms gain electrons and form negatively
  charged ions, they always become larger

21
Lose Electrons ? Smaller ionic radii
Gain Electrons ? larger ionic radii
22
Ionization Energy (I.E.)

• Ionization Energy- the energy required to remove
  an electron from a gaseous atom
• 1st Ionization Energy- removes the 1st electron
• 2nd Ionization Energy- removes the 2nd electron
  and so forth
• I.E. is an indication on how strongly an atoms
  nucleus holds onto its valence electrons

23
Octet Rule- atoms tend to gain, lose or share
electrons in order to acquire a full set of eight
valence electrons
24

• Octet Rule- atoms tend to gain, lose or share
  electrons in order to acquire a full set of eight
  valence electrons
• Hydrogen and Helium are exceptions (theyll be
  happy with 2 V.E.)
• Determines the types of ions likely to form
• Elements on the right side tend to gain electrons
• Elements on the left side tend to lose electrons

25
Electronegativity

• Indicates the relative ability of its atoms to
  attract electrons in a chemical bond
• Noble gases form very few compounds so they are
  left out
• In a chemical bond, the atom with the greater
  electronegativity more strongly attracts the
  bonds electrons

26
(No Transcript)
27
In Summary
Atomic radius decreases Ionization energy
increases Electronegativity increases
Atomic radius increases Ionization energy
decreases Electronegativity decreases
1A
0
2A
3A
4A
6A
7A
5A
28
Matching Words for Test

• Electronegativity
• Ionization energy
• Atomic radius
• Metal
• Transition metal
• Anion

• Periodic law
• Cation
• Period
• Group
• Electrons
• Nonmetal

29
Homework

• Page 174-175
• 29-38
• 40-45
• 47-76