Exploring the Periodic Table

1
Chapter 5

• Exploring the Periodic Table
• Elemental Properties

2
Chapter 5 Objectives

• At the end of this section you will be able to
• Explain the shape of the periodic table.
• Explain why elements in columns have similar
  chemical properties.
• Determine if an element has metallic, nonmetallic
  or metalloid properties because of its location
  on the table.
• Label the common families on the table.

3
Chapter 5 Objectives (Continued)

• Determine the charge of an elements ion based on
  its location in the table.
• Will understand the filling order of orbitals and
  energy levels
• Write the electron configuration of an element.
• Identify periodicity use the Periodic Law to
  explain these patterns.

4
Intro to the PT

• The periodic table is a tool that has no likeness
  in any other field of science
• Despite dramatic changes in technology the
  discovery of many new elements, there has been no
  need to change the basic setup of the table.
• The PT allows chemists to function by mastering
  the properties of only a few elements.

5
Intro II

• The discovery of the periodic system used to
  classify elements is a combined work of a number
  of scientists, not a sudden realization by a
  single researcher.
• The power of the periodic table lies in the two
  or three dimensional display of all the known
  (and unknown) elements in a logical system of
  precisely ordered rows and columns.

6
Early Attempts to Organize the Elements

• Triads, Octaves Tables

7
Dobereiner (1817)

• His focus was to organize the elements known at
  the time
• Noticed a trendthe mass of the middle element
  was approximately the average of the masses of
  the first and third elements
• Just as the mass was equal to the average, so
  were the chemical/physical properties.
• He called these sets of three consecutive
  elements with similar properties triads

8
Newlands (1864)

• Was the first to use a sequence of common numbers
  to organize elements.
• He arranged the known elements by mass.
• Noticed a trend, elements showed similar
  properties with those elements seven before and
  after them.

9
Newlands II

• Newlands coined the phrase Law of Octaves.
• The Law of octaves states that an element will
  share similar properties with those that are
  seven places before and after it.
• Newlands knew there were elements missing, but he
  was not able to determine what they were.

10
Mendeleev (1869)

• While in the process of writing a chemistry text,
  he developed an effective way to organize the
  elements according to their atomic mass and
  similarities in chemical properties.
• By incorporating similar chemical properties he
  noticed periodic similarities between
  elementsso he placed them in the same columns in
  his table.

11
Mendeleev II

• By incorporating chemical and physical properties
  into the organization method he was able to
  accurately predict the masses and properties of
  the unknown elements.
• Although his method of arranging elements by mass
  did cause some elements to appear out of place
• (Te I).

12
Terms from Mendeleev

• Periodic refers to the way that elements show
  patterns in their chemical properties that tend
  to repeat at regular intervals.
• Periodicity refers to the repetition of
  properties in certain, regular intervals.

13
Valence Electrons

• Valence electrons are the electrons in the
  highest energy level (those farthest from the
  nucleus).
• Valence electrons are the only electrons that
  take part in reactions.
• Thus the valence electrons will determine the
  properties of the element.
• Every Group has a distinct of valence electrons.

14
Lewis Dot Notation

• This is a way to show the number of electrons in
  the highest energy levels without having to draw
  the full Bohr Model of the atom

15
To Make a Lewis Dot

• Write the element symbol from the Periodic Table.
• Determine the of Valence Electrons by looking
  at the group .
• Show the electrons with X around the symbol in
  the 12, 3, 6 9 positions.
• P

16
Valence Electrons for Main Group Elements

• 2 3 12 13 14 15 16 17 18
• H He
• Li Be TM B C N O
  F Ne
• Na Mg Al Si P
  S Cl Ar
• Notice that every time you start a new period on
  the table you begin the trend all over again!

17
Valence Electrons by Groups

• Group 1 ? 1 e-
• Group 2 ? 2 e-
• Group 3-12 ? 2 e- (refer to s/p/d/f blocks)
• Group 13 ? 3 e-
• Group 14 ? 4 e-
• Group 15 ? 5 e-
• Group 16 ? 6 e-
• Group 17 ? 7 e-
• Group 18 ? 8 e-

18
The Modern Periodic Table

• Noble Gases
• Atomic Numbers

19
Ramsay (1894)

• Ramsay discovered the Noble Gases, a group of
  gaseous elements that did not combine with any
  other elements to form compounds, in 1894.
• He Named them Noble Gases since they did not mix
  with other groups of elements just like nobility
  does not mix with commoners.

20
Moseley (1913)

• Moseley discovered that each element had a
  distinct number of protons in the nucleushe
  called this the atoms Atomic Number
• He arranged the elements in order of increasing
  atomic number.

21
Moseley II

• By arranging the elements according to increasing
  atomic number he was able to correct the ? in
  Mendeleevs Table.
• The discovery of the atomic number showed that
  there was a fundamental quantity that increased
  by regular steps when we pass from one element to
  another.

22
Moseley III

• The Atomic and the fact that it increased by
  one for each element allowed us to determine the
  number of missing elements.
• After his discovery Chemists accepted the atomic
  as the principal method for arranging the
  elements on the periodic table.

23
The Periodic Law

• The physical and chemical properties of the
  elements are periodic functions of their atomic
  number.

24
The Periodic Table

• Is an arrangement of elements in order of atomic
  number so that elements with similar properties
  fall into the same column (also called a group or
  Family).

25
Capacities of Energy Levels

• Here is a quick formula to remember the of
  electrons that an energy level can hold
• e- in an EL 2(EL)2

26
The Shape of the Periodic Table

• The PT is shaped the way it is because there are
  four major regions that are placed relative to
  one another.
• We call these regions Blocks but they actually
  help us determine the type of orbital the
  elements electrons are in especially their
  valence electrons.

27
The s Block

• Is the first two columns in the PT.
• All of the elements in these two columns have
  their first and second outer shell electrons in
  the s orbital.
• The s orbital is shown to the left.
• It is a 3-D Sphere with the nucleus _at_ the center.

28
The p Block

• The p block is the group of six columns ( 13
  18)
• The elements in this block have their third
  eighth valence electrons in the p orbital that
  has the shape seen off to the right.

29
The d Block

• The d Block contains all the elements in
  columns 3 12.
• The energy level of the d block is always one
  less than the period number.
• After the s block fills the electrons in the
  4th 7th energy levels drop down to a the
  previous energy level.

30
The d Block II

• Think of it this way
• The 4s fills up with the 19th 20th
  electronsthe 21st 30th electrons do not have
  sufficient to get themselves into the 4p yet
  there is still room in the 3rd EL (remember the
  3rd EL holds 18 electrons).
• The electrons that lack the energy to get to the
  4p go back down to the 3rd energy level to
  generate the 3d orbitals.

31
The f Block

• The f block has such a confusing shape to its
  orbitals that I am not even going to place it
  here.
• The thing that you need to remember is that the
  lanthanides and actinides (the two rows of
  elements at the bottom of the PT) are what makes
  up the f block.

32
The f Block II

• The for the f block is always equal to the
  period - 2
• You will see that they fit in between column 3
  4 in period 6 7.

33
Why only 8 valence e-?

• If you look at the 4th EL you will see that there
  are 18 elements in the period. BUT there are only
  8 valence electrons.
• WHY? Because the elements in groups 3 12 are in
  the lower, 3rd EL. Therefore there are only 8
  electrons on the highest energy levelEL 4.

34
The Diagonal Rule
35
Filling Order of Sublevels

• Use the Diagonal Rule to help you determine the
  order in which electrons are placed in to each
  sublevel.

36
Ionization

• They all Want to be Noble

37
The Octet Rule

• Elements are most stable when they attain eight
  electrons in their outer energy level.

38
Stability via Ionization

• In order to get the octet all elements except the
  Noble Gases must lose or gain electrons.
• If the element has between 1 3 electrons in the
  valence shell then it will lose electrons.
• If the element has between 5 7 electrons then
  the element will gain electrons.

39
Stability via Ionization II

• If the element has 4 valence electrons it is
  caught in the middle so whether it gains or loses
  electrons depends on the elements it comes into
  contact with during the period of time when it
  ionizes.

40
The Major Classes

• Metals, Nonmetals Metalloids

41
The 3 Classes of Elements

• Metals - Elements that lose electrons when
  forming compounds.
• Nonmetals - Elements that gain electrons when
  forming compounds.
• Metalloids - elements that have properties of
  both metals nonmetals.

42
Location
43
The Metalloids

• The following elements are the Metalloids
• Boron
• Silicon
• Germanium
• Arsenic
• Tellurium
• Some texts include Polonium Astatine but, they
  really are not true metalloids

44
Metal Properties

• Metals are
• Lustrous - they are shiny
• Ductile - they can be drawn into thin strands
• Malleable - they are able to be shaped
• Conductive - transfer heat and electricity very
  efficiently
• Lose electrons when forming compounds

45
Nonmetal Properties

• Nonmetals are
• Gases or brittle solids
• Have dull surfaces
• Are insulators - they do not transfer heat and
  electricity well.

46
Metalloid Properties

• Metalloids have a mixture of M NM properties
• They may be good conductors but are also brittle.
• May be lustrous but not malleable