1. Electrons and the Periodic Table
Cartoon courtesy of NearingZero.net

2. The periodic table is the most important tool in the chemist’s toolbox!

3. How the Elements Were Won
Your Guide to the History of the Periodic Table
and the Periodic Law

4. 1829 Johann Dobereiner Model of triads
-classified some elements into groups of three or triads. -elements in a triad had similar chemical and physical properties.
(ex. Cl, Br, I and Ca, Sr, Ba)
Model of triads

5. 1868 Dmitri Mendeleev “Father of the Periodic Table”
Arranged known elements in order of increasing atomic mass
Noticed that similar properties repeated in regular intervals

6. Mendeleev’s Original Table How is it different from the one we use today?

7. Mendeleev and Periodic Solitaire
Where gaps occurred, Mendeleev predicted the existence of new elements and their properties
Mendeleev was right – three of the elements he predicted were discovered in his lifetime

8. 1913 Henry Moseley
He rearranged the elements in order of increasing atomic number to fix Mendeleev’s mistakes.

9. Henry Moseley
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 sniper’s bullet, at the age of 28. Because of this loss, the British government later restricted its scientists to noncombatant duties during WWII.

10. 1944 Glenn T. Seaborg
co-discovering 10 new elements, - moved the Actinide series out of the main body of the periodic table to their current location

11. Glenn T. Seaborg
He is the only person to have an element named after him while still alive.
"This is the greatest honor ever bestowed upon me - even better, I think, than winning the Nobel Prize."
Watch Island of Stability YT Vid

12. Modern Periodic Table still arranged by increasing atomic number
This establishes the Periodic law
When the elements are arranged in order of increasing atomic #, there is a periodic repetition of their physical & chemical properties

13. Stowe Periodic Table
7th

14. A Spiral Periodic Table

15. “Mayan” Periodic Table

17. Ch 6.2 –
Classifying the Elements

18. On your copy of the periodic table label the following:
Periods
Groups
Metals
Nonmetals
Metalloids
Alkali metals
Alkali Earth Metals
Halogens
Noble Gases
Representative elements
Transition metals
Inner transition metals

20. The horizontal rows of the periodic table are called PERIODS.

21. The elements in any group of the periodic table have similar physical and chemical properties!
The vertical columns of the periodic table are called GROUPS, or FAMILIES.

22. Metals, Nonmetals, and Metalloids
Types of Elements
Metals, Nonmetals, and Metalloids

23. Periodic Table: Metallic arrangement
Layout of the Periodic Table: Metals vs. nonmetals
Nonmetals
Metals

24. Properties of Metals Good conductors of heat and electricity
(sea of mobile e-)
Malleable
Ductile
High mp
Have luster
Reactivity increases as move down a column.
Tend to lose electrons to form cations (+)

25. Examples of Metals
Potassium, K reacts with water and must be stored in kerosene
Copper, Cu, is a relatively soft metal, and a very good electrical conductor.
Zinc, Zn, is more stable than potassium
Mercury, Hg, is the only metal that exists as a liquid at room temperature

26. Alkali Metals Group 1A (excluding hydrogen) 1 valence electron
readily forms +1 cation [(+) ion]
React violently with water
Too reactive
to be found in
nature in pure
Form.

27. Alkaline Earth Metals Group 2A Ca, Ba, and Sr react with water
2 valence electrons
Readily form +2 cation
Too reactive to be found in nature in pure form

28. Transition metals Good conductors of electricity
Ions responsible for colors in solutions and gem stones
Also, they are not very reactive.
What would we do if gold (Au) was reactive?

29. Most Reactive Metal Easier to lose e- The farther it is from Nucleus
(shielding)

30. Properties of Nonmetals
Carbon (the graphite in “pencil lead”) is a great example of a nonmetallic element.
Poor conductors
Tend to be brittle
Many are gases at room temp.
Low mp
dull
Gain e- to become anions (-)

31. Examples of Nonmetals
Microspheres of phosphorus, P, a reactive nonmetal
Sulfur, S, was once known as “brimstone”
Graphite is not the only pure form of carbon, C. Diamond is also carbon; the color comes from impurities caught within the crystal structure

32. Halogens 7A or 17 Highly reactive group Most are gases
7 valence electrons
from -1 anion
[(-) ion]

33. Most Reactive Non Metal
Easier to gain e-
The closer it is to
Nucleus

34. Noble Gases Group 8A or 18 Most stable group Full outer energy level
Stable Octect
Not completely inert
Xe actually
can react

35. Properties of Metalloids
Metalloids straddle the border between metals and nonmetals on the periodic table.
Have properties of both metals and nonmetals
More brittle than metals, less brittle than most nonmetallic solids
Semiconductors of electricity
Some metalloids possess metallic luster

36. Silicon, Si – A Metalloid
Has metallic luster
Brittle like a nonmetal
Semiconductor of electricity
Other metalloids include:
Boron, B
Germanium, Ge
Arsenic, As
Antimony, Sb
Tellurium, Te

38. Periodic Trends

39. Periodic Properties
Perodicity = properties repeat in predictable patterns
An element’s properties directly related to the number of valence electrons

40. Atomic Radii Atomic Radii
Is always measured under the same conditions for each atom.
Is always half the distance between the nuclei of identical atoms bonded together.
If this is chlorine what is its radius?
Chlorine Nucleus
Atomic Radius = ?
Chlorine Nucleus
Distance between nuclei = 198pm

41. Atomic Radius Do you predict the size of the atoms will increase or
decrease as you move right across a period?

42. Why do patterns appear? The # of energy levels remains the same
The # of valence e- increases
The # of protons in the nucleus increases resulting
in greater effective nuclear charge (greater
magnetic pull on the valence e-)
Trends Across a Period

43. Number of energy levels increases
The elements have the same number of valence e- in the same type of orbital
The valence e- are further from the nucleus and don’t feel it’s pull as much due to shielding by internal e-.
Trends Down a Family

44. Atomic Radius Down a family: atoms get larger ( more energy levels)
Across a period:
left to right atoms get smaller due to more protons
(protons pull shells closer)

46. Electronegativity Linus Pauling (American chemist)
devised a scale to measure electronegativity
Electronegativity – tendency of an atom in a compound to attract electrons
“Selfishness”
F- most electronegative element
arbitrarily assigned a value of 4
Values for the other elements-calculated in relation to this value

48. Periodic Table of Electronegativities

49. Ionization Energy Ionization energy (potential)
Energy needed to remove one of an atom’s e-s.
If the e-s are held strongly the atom will have a high ionization energy
Therefore, nonmetals whose valence e- are close to nucleus have highest IE.

50. Size of Ions (penny demo)
Cations, (+) ions = lose electrons
SMALLER than original atom
Anions, (-) ions = gain electrons
LARGER
than original atom

51. Octet Rule
Outer Shell of 8 makes an atom “feel” great! (Chemical stability!)
Octet Rule: atoms tend to gain, lose, or share electrons in order to acquire
8 valence electrons

52. Ions
Elements in a group tend to form ions of the same charge
Modeled by electron configurations
[Ar] 4s K:
Loses 1
electron
[Ar] 4s
Wants a full set of e- (like a noble gas) K +1

53. O: [He] [He] Ions -2 O 2s2 2p4 Gains 2 electrons Wants a complete set
(like a noble gas)
[He] O -2

54. Ionic Charges/Oxidation #s1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 +1 +2 +3
+/- 4 -3 -2 -1
+ 3
+ 3 or + 4
tend to have
more than one option