1. The Periodic Table

2. Organizing the Elements
OBJECTIVES:
Identify three broad classes of elements.

3. Organizing the Elements
OBJECTIVES:
Explain how elements are organized in a periodic table.

4. What is an Element?
Before we begin let us first talk about what an element is…
An element is a material which cannot be broken down or changed into another substance using chemical means
they are made of atoms
They are floating all around us all the time
They are what makes life function
Without elements you would not exist

5. Remember the Atom Atom-
The basic unit of matter made up of three subatomic particles
Protons- positively charged
Located in the nucleus
Neutrons- no charge
Electrons- negatively charge
Encircling the nucleus

6. The Atom
Now the protons and neutrons stay in the nucleus and most often do not undergo reactions
When the nucleus is disrupted the results are severe…
i.e.
Star Formation
Nuclear explsion

7. The Atom That leaves us with the electron…
Electrons float around the nucleus
They reside in levels and the outermost level is the valance level/shell
This is where the valance electrons reside
These are the electrons in the outermost shell and these are the electrons that undergo chemical reactions
Now remember these electrons can be lost or gained resulting in a change in charge of the atom (more on this later)

8. Elements So back to the elements for a moment
Elements are represented by symbols
The elemental symbols are either a single letter or a series of letters (2 or 3)
A capital letter always represents a new element
If an element has another letter the second/third letters are always lower case
i.e.
C represents Carbon
Co represents Cobalt
CO represents Carbon and Oxygen (Carbon Monoxide)

9. Atomic Number? So what is the Atomic Number?
The atomic number is the atom’s number
It is the number of protons in a given element
Therefore the number of protons always defines the element
For neutral atoms the atomic number is also the number of neutrons and electrons
Because neutral atoms will have the same number of electrons and protons
And unless the atom is an isotope the number of protons and neutrons are always the same

10. Useful Definitions
Isotope- an atom with a different number of neutrons than protons
Neutrons have been lost or gained
Mass Number- the mass of an atom
made up of the neutrons and protons
The Periodic Table of Elements actually use the average mass of all the isotopes of the element

11. Back to the Periodic Table
The elements are all arranged for us on the Periodic Table of Elements

12. Why is the Periodic Table important to me?
The periodic table is the most useful tool to a chemist.
You get to use it on every test.
It organizes lots of information about all the known elements.

13. Pre-Periodic Table Chemistry …
…was a mess!!!
No organization of elements.
Imagine going to a grocery store with no organization!!
Difficult to find information.
Chemistry didn’t make sense.

14. Dmitri Mendeleev: Father of the Table
HOW HIS WORKED…
Put elements in rows by increasing atomic weight.
Put elements in columns by the way they reacted.
SOME PROBLEMS…
He left blank spaces for what he said were undiscovered elements. (Turned out he was right!)
He broke the pattern of increasing atomic weight to keep similar reacting elements together.

15. The Current Periodic Table
Mendeleev wasn’t too far off.
Now the elements are put in rows by increasing ATOMIC NUMBER!!
The horizontal rows are called periods and are labeled from 1 to 7.
The vertical columns are called groups are labeled from 1 to 18.

16. Organizing the Elements
A few elements, such as gold and copper, have been known for thousands of years - since ancient times
Yet, only about 13 had been identified by the year 1700.
As more were discovered, chemists realized they needed a way to organize the elements.

17. The Periodic Law says:
When elements are arranged in order of increasing atomic number, there is a periodic repetition of their physical and chemical properties.
Horizontal rows = periods
There are 7 periods
Vertical column = group (or family)
Similar physical & chemical prop.
Identified by number & letter (IA, IIA)

18. Areas of the periodic table
Three classes of elements are: ) metals, 2) nonmetals, and ) metalloids
Metals: electrical conductors, have luster (shine), ductile, malleable
Nonmetals: generally brittle and non-lustrous, poor conductors of heat and electricity

19. Areas of the periodic table
Properties of non-metals
Some nonmetals are gases (O, N, Cl)
some are brittle solids (S)
one is a fuming dark red liquid (Br)
Notice the heavy, stair-step line?
Metalloids/Semimetals: border the line-2 sides
Properties are intermediate between metals and nonmetals

21. Classifying the Elements
OBJECTIVES:
Describe the information in a periodic table.

23. Squares in the Periodic Table
The periodic table displays the symbols and names of the elements, along with information about the structure of their atoms:
Atomic number and atomic mass

26. What does the information in the box tell me?1 H
Hydrogen
1.008
Atomic Number = # of protons
Elemental Symbol
Atomic Mass = # of protons plus neutrons
Element Name

27. Element Square

29. Groups of elements - family names
Group IA – alkali metals
Forms a “base” (or alkali) when reacting with water (not just dissolved!)
Group 2A – alkaline earth metals
Also form bases with water; do not dissolve well, hence “earth metals”
Group 7A – halogens
Means “salt-forming”

30. The Groups of the Periodic Table
Group 1: The Alkali Metals
Most reactive metals on the PT
Rarely found free in nature
Charge of 1—1 valence electron
Group 2: The Alkaline Earth Metals
Still quite reactive
Charge of 2—2 valence electrons

31. T he Groups of the Periodic Table
Groups 3-12: Transition Metals
Found freely and in compounds in nature
Charge is usually 2 but can vary—usually 2 valence electrons
Group 13: Boron Family
Charge is 3—3 valence electrons

32. The Groups of the Periodic Table
Group 14: The Carbon Family
Contains elements that can form unusual bonds (carbon and silicon)
Charge is +4 or -4—contains 4 valence electrons
Group 15: The Nitrogen Family
Charge is -3—contains 5 valence electrons

33. The Groups of the Periodic Table
Group 16: The Oxygen Family
Also known as the chalcogens
Charge is -2—6 valence electrons
Group 17: The Halogens
Most reactive nonmetals
charge is -1—7 valence electrons
Group 18: The Noble Gases (The Inert Gases)
Nonreactive
Charge is 0—2 or 8 valence electrons

34. The Periodic Table Column = Group or Family
18 columns on the Periodic Table
Row = Period
7 rows on the Periodic Table

35. Metals, Nonmetals, and Semi-metals
Only
nonmetal on the metal side
Nonmetals are on the right of the stair-step
Metals are to the left of the stair- step
Semi-metals,
“metalloids,”
touch the stair-step

36. Special Rows on the PT
Lanthanides
Actinides

38. Classifying the Elements
OBJECTIVES:
Distinguish representative elements and transition metals.

39. Groups…Here’s Where the Periodic Table Gets Useful!!
Elements in the same group have similar chemical and physical properties!!
(Mendeleev did that on purpose.)
Why??
They have the same number of valence electrons.
They will form the same kinds of ions.

40. Families on the Periodic Table
Columns are also grouped into families.
Families may be one column, or several columns put together.
Families have names rather than numbers. (Just like your family has a common last name.)

41. Elements in the 1A-7A groups are called the representative elements
outer s or p filling 1A 8A 2A 3A 4A 5A 6A 7A

42. The group B are called the transition elements
These are called the inner transition elements, and they belong here

43. Hydrogen Hydrogen belongs to a family of its own.
Hydrogen is a diatomic, reactive gas.
Hydrogen was involved in the explosion of the Hindenberg.
Hydrogen is promising as an alternative fuel source for automobiles

44. Alkali Metals
1st column on the periodic table (Group 1) not including hydrogen.
Very reactive metals, always combined with something else in nature (like in salt).
Soft enough to cut with a butter knife

45. Group 1A are the alkali metals (but NOT H)
Group 2A are the alkaline earth metals H

46. Alkaline Earth Metals Second column on the periodic table. (Group 2)
Reactive metals that are always combined with nonmetals in nature.
Several of these elements are important mineral nutrients (such as Mg and Ca

47. Transition Metals Elements in groups 3-12 Less reactive harder metals
Includes metals used in jewelry and construction.
Metals used “as metal.”

48. Boron Family Elements in group 13
Aluminum metal was once rare and expensive, not a “disposable metal.”

49. Carbon Family Elements in group 14
Contains elements important to life and computers.
Carbon is the basis for an entire branch of chemistry.
Silicon and Germanium are important semiconductors.

50. Nitrogen Family Elements in group 15
Nitrogen makes up over ¾ of the atmosphere.
Nitrogen and phosphorus are both important in living things.
Most of the world’s nitrogen is not available to living things.
The red stuff on the tip of matches is phosphorus.

51. Oxygen Family or Chalcogens
Elements in group 16
Oxygen is necessary for respiration.
Many things that stink, contain sulfur (rotten eggs, garlic, skunks,etc.)

52. Halogens Elements in group 17
Very reactive, volatile, diatomic, nonmetals
Always found combined with other element in nature .
Used as disinfectants and to strengthen teeth.

53. Group 8A are the noble gases
Group 7A is called the halogens

54. The Noble Gases

55. The Noble Gases Elements in group 18 VERY unreactive, monatomic gases
Used in lighted “neon” signs
Used in blimps to fix the Hindenberg problem.
Have a full valence shell.

56. Electron Configurations in Groups
Elements can be sorted into 4 different groupings based on their electron configurations:
Noble gases
Representative elements
Transition metals
Inner transition metals
Let’s now take a closer look at these.

57. Electron Configurations in Groups
1) Noble gases are the elements in Group 8A (also called Group18 or 0)
Previously called “inert gases” because they rarely take part in a reaction; very stable = don’t react
Noble gases have an electron configuration that has the outer s and p sublevels completely full

58. Electron Configurations in Groups
Representative Elements are in Groups 1A through 7A
Display wide range of properties, thus a good “representative”
Some are metals, or nonmetals, or metalloids; some are solid, others are gases or liquids
Their outer s and p electron configurations are NOT filled

59. Electron Configurations in Groups
Transition metals are in the “B” columns of the periodic table
Electron configuration has the outer s sublevel full, and is now filling the “d” sublevel
A “transition” between the metal area and the nonmetal area
Examples are gold, copper, silver

60. Electron Configurations in Groups
Inner Transition Metals are located below the main body of the table, in two horizontal rows
Electron configuration has the outer s sublevel full, and is now filling the “f” sublevel
Formerly called “rare-earth” elements, but this is not true because some are very abundant

61. Elements in the 1A-7A groups are called the representative elements
outer s or p filling 1A 8A 2A 3A 4A 5A 6A 7A

62. The group B are called the transition elements
These are called the inner transition elements, and they belong here

63. Group 1A are the alkali metals (but NOT H)
Group 2A are the alkaline earth metals H

64. Group 8A are the noble gases
Group 7A is called the halogens

65. 1s1
1s22s1
1s22s22p63s1
1s22s22p63s23p64s1
1s22s22p63s23p64s23d104p65s1
1s22s22p63s23p64s23d104p65s24d10 5p66s1
1s22s22p63s23p64s23d104p65s24d105p66s24f145d106p67s1 H 1 Li 3 Na 11 K 19 Rb 37 Cs 55 Fr 87
Do you notice any similarity in these configurations of the alkali metals?

66. 1s2
1s22s22p6
1s22s22p63s23p6
1s22s22p63s23p64s23d104p6
1s22s22p63s23p64s23d104p65s24d105p6
1s22s22p63s23p64s23d104p65s24d10 5p66s24f145d106p6 He
Do you notice any similarity in the configurations of the noble gases? 2 Ne 10 Ar 18 Kr 36 Xe 54 Rn 86

67. Elements in the s - blocks
Alkali metals all end in s1
Alkaline earth metals all end in s2
really should include He, but it fits better in a different spot, since He has the properties of the noble gases, and has a full outer level of electrons.

68. The P-block p1 p2 p3 p4 p6 p5

69. Each row (or period) is the energy level for s and p orbitals.1 2 3 4 5 6 7
Period Number
Each row (or period) is the energy level for s and p orbitals.

70. The “d” orbitals fill up in levels 1 less than the period number, so the first d is 3d even though it’s in row 4. 1 2 3 4 5 6 7 3d 4d 5d

71. f orbitals start filling at 4f, and are 2 less than the period number1 2 3 4 5 6 7 4f 5f
f orbitals start filling at 4f, and are 2 less than the period number