Periodic Table

1
Periodic Table

• What is it, and how is it useful?

2
Periodic Table

• An overall arrangement of elements by increasing
  atomic number, a vertical arrangement by number
  of valence electrons, and a horizontal
  arrangement by number of energy levels.

3
History - Mendeleev

• In 1869 he published a table of the elements
  organized by increasing atomic mass. He was so
  confident in his table that he used it to predict
  the physical properties of three elements that
  were yet unknown.
• However, in spite of Mendeleevs great
  achievement, problems arose when new elements
  were discovered and more accurate atomic weights
  determined.

4
History - Mosley

• In 1913, through his work with X-rays, he
  determined the actual nuclear charge (atomic
  number) of the elements. He rearranged the
  elements in order of increasing atomic number.
• His research was halted when the British
  government sent him to serve as a foot soldier in
  WWI. He was killed in the fighting in Gallipoli
  by a snipers bullet, at the age of 28. Because
  of this loss, the British government later
  restricted its scientists to noncombatant duties
  during WWII.

5
Periodic Law

• States that the physical and chemical properties
  of elements are periodic functions of their
  atomic numbers.

6
More details.

• The individual boxes within the table generally
  give the elements name, symbol, atomic number,
  and atomic mass.

7
Group

• A vertical arrangement of elements by number of
  valence electrons.
• The groups are numbered 1-18

8
Group (cont)

• The LAST DIGIT of the groups 1, 2, and 13-18
  tells you how many valence electrons the elements
  in the group have.
• So all elements in group 1 have 1 valence
  electron
• All elements in group 15 have 5 valence electrons

9
Group Names

• Certain groups have special names assigned to
  them.

10
Group Names (cont)

• Group 1 - Alkali Metals
• Group 2 Alkaline Earth Metals
• Group 3-12 Transition metals
• Group 17 Halogens
• Group 18 Noble Gases

11

• Yes, you have to memorize the group numbers
  and names.

12
Periods

• Horizontal arrangement of elements by number of
  energy levels.
• Numbered 1-7 and the period number tells how many
  energy levels each element has.
• Also tells which energy level is the valence

13
Metals VS Non-Metals

• Every element to the left of the staircase line
  is a metal (EXCEPT HYDROGEN)
• Every element to the right of the staircase line
  is a non-metal
• Hydrogen is a NON-METAL (exception to the rule)

14
Properties of Metals

• Shiny (luster)
• Malleable (pounded into thin sheets)
• Ductile (made into wire)
• Good conductors (of heat and electricity)

15
Metalloids

• Elements that are found along the staircase line
• Have properties of both metals and non-metals
• Must touch the staircase line
• to be a metalloid

16
Reactivity

• Elements become more reactive as you move from
  top to bottom on the periodic table.
• The alkali metals are the more reactive group of
  elements on the periodic table.

17
Size of Atoms

• As you move left to right on a row, the elements
  become smaller (due to increasing pull on the
  electrons)
• As you move top to bottom in a group, the
  elements become larger.
• Each additional energy level causes a large
  increase in size.