1. Chapter 5 The Periodic Table

2. 5.1 Organizing the Elements:
Key Concepts:
·         Mendeleev arranged the elements into rows in order of ­­­­­­­­­­­­ increasing mass so that elements with similar properties were in the same column.
·         The close match between Mendeleev’s predictions and the actual properties of new elements showed how useful his periodic table could be.

3. Why is the Periodic Table important to me?
The periodic table is the most useful tool in chemistry.
You get to use it on quizzes and tests!
It organizes lots of information about all the known elements.

4. 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.

5. Dmitri Mendeleev: Father of the Table
Previous attempts to organize known elements failed to work for all known elements at the time
Russian Chemist and teacher, Dmitri Mendeleev, discovered a way
Found a way to approach the problem when playing his favorite card game, a version of solitaire (organization was the key)
Solitaire…??????

6. How does the game of solitaire work???

8. Dmitri Mendeleev: Father of the Table
HOW HIS WORKED…
Put elements in rows by increasing atomic weight.
Elements with similar properties were in the same column.
Put elements in columns by the way they reacted.

9. Mendeleev’s Periodic Table
Periodic Table: an arrangement of elements in columns, based on a set of properties that repeat from row to row

10. Mendeleev’s Prediction
Table was not complete, not all elements had yet been discovered
He left gaps/spaces in his table for those elements
He was NOT the first to organize the elements in the form of a table
He was the FIRST to offer good explanations for how the properties of an element were related to its location in his table
He used the gaps in his tables to predict properties of undiscovered elements
Other scientists used the predictions to help in their search for undiscovered elements

11. Evidence Supporting Mendeleev’s Table
The close match between Mendeleev’s predictions and the actual properties of new elements showed how useful his periodic table could be
With the periodic table, chemists could do more than predict the properties of new elements – they could explain the chemical behavior of different groups of elements!!!

12. 5.2  The Modern Periodic Table

13. 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.

14. PERIODS Period: A row in a periodic table of elements (left to right)
To understand the structure of the table, think what happens as the atomic number increases:
Reminder: Atomic Number = Number of Protons
First energy level has ONLY 1 orbital
The 1 e- in a hydrogen atom and 2 e- in a helium atom can fit in this orbital (first energy level)
This is why H and He are in Period 1

15. PERIODS
Lithium, 1st element in Period 2, has one of its the three electrons in the second energy level
This is why lithium is the first element in Period 2
Sodium, 1st element in Period 3, has one e- in its third energy level
Potassium, 1st element in Period 4, has 1 e- in its fourth energy level
This pattern applies to ALL the elements in the 1st column on the table 

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

17. Groups Group: A column in a periodic table of elements
Properties of elements repeat in a predictable way when atomic numbers are used to arrange elements into groups

18. Groups
Periodic Law: the pattern of repeating properties displayed by elements in the periodic table
Elements within a group have similar properties:
Similar e- configurations (see example above – first column of the table)
Electron configuration determines an elements chemical properties

19. Various Trends of the Periodic Table

20. Atomic Mass
Atomic mass is a value that depends on the distribution of an element’s isotopes in nature and the masses of those isotopes.

21. Atomic Mass Units Mass of an atom in grams is EXTREMELY small
Scientists came up with an easier way to talk about mass
Chose one isotope to serve as a standard
Scientists assigned 12 atomic mass units (amu’s) to the carbon-12 atom (which has 6P and 6N)
Atomic Mass Unit (amu): 1/12 the mass of a carbon-12 atom

22. An Example…Isotopes of Chlorine
Chlorine has an atomic number of 17 and an atomic mass of atomic mass units
Where does the number come from???
There are two natural isotopes of Chlorine:
Chlorine-35 which has 17 protons and 18 neutrons
Chlorine-37 which has 17 protons and 20 neutrons

23. It’s a weighted average of the isotopes
Atomic masses come from an average of the isotopes for a given element that exist in nature
The value for atomic mass is known as a “weighted average”
Cl-35 occurs 3 times as often as Cl-37
Take an average of those numbers: (3 × 35) + (1 × 37) =

24. Classes of Elements
Elements are classified as metals, nonmetals, and metalloids.

25. Metals

26. Metals
Metals: elements that are good conductors of electric current and heat.
Properties of Metals:
Except for mercury, metals are solid at room temperature
Most metals are malleable
Many metals are ductile (can be drawn into thin wires)
Some metals are extremely reactive* (page 135, figure 10)
*Meaning they easily combine chemically with other elements

28. Transition Metals
Transition Metals: metals in groups 3-12, form a bridge between the elements on the left and right sides of the tables.
Examples: copper and silver
Some of the first elements discovered
Ability to form compounds with distinctive colors (page 137  production of colored glass)
Includes the lanthanide and actinide series (at the bottom of the table)

31. Nonmetals

32. Nonmetals
Nonmetals: elements that are poor conductors of heat and electric current
Properties opposite those of metals
Low boiling points
Most are gases at room temperature
Nonmetals that are solid at room temperature tend to be brittle (will shatter)
Some very reactive, some not at all, some fall somewhere in between
Fluorine (in Group 17) is the most reactive nonmetal (found in toothpaste)

34. Metalloids

35. Metalloids
Metalloids: elements with properties that fall between those of metals and nonmetals
Ability to conduct electric current varies with temperature
Pure silicon (Si) and germanium (Ge) are good insulators at low temperatures and good conductors at high temps.

38. Variation Across a Period
Across a period from left to right, the elements become less metallic and more nonmetallic in their properties
Most reactive metals on left side
Most reactive nonmetals on the right side (in Group 17)
Period 3 elements (left to right) provide an example of this (page 138, Figure 13)

39. 5.3  Representative Groups

40. Hydrogen…
Why is hydrogen (H) on the left side of the table with the active metals?
Hydrogen’s location is related to its electron configuration, not its properties!!!

41. Patterns of Electron Configuration
Wonder why there are 2 numbering schemes on the periodic table?
When the ‘A’ groups are numbered 1-8, they provide a reminder about the electron configurations of the elements in those groups
The number of an ‘A’ group matches the number of valance electrons in an electron configuration for an element in that group

42. Valence Electrons
Valence Electron: an electron that is in the highest occupied energy level of an atom
Valence electrons play a key role in chemical reactions
Properties vary across a period because the number of valence electrons increases from left to right
Elements in a group have similar properties because they have the same number of valence electron
Hydrogen is on far left of table because it has one valence electron, just like the rest of the elements in that column

43. Valence Electrons

44. Valence Electrons  Lewis Structure

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

47. Alkali Metals- Lt. Blue
1st column on the periodic table (Group 1 /1A) not including hydrogen.
Very reactive metals, always combined with something else in nature (like in salt).

48. Alkali Metals Single valence electron
Soft enough to cut with a butter knife.
The reactivity of alkali metals increases from the top of Group 1A to the bottom
Lithium (Li) down through Francium (Fr)

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

52. Alkaline Earth Metals 2 valence electrons
Harder than metals in Group 1A
Higher melting point than Group 1A
Differences in reactivity among the alkaline earth metals are shown by the ways they react with water
Calcium, strontium, and barium react easily with cold water
Magnesium reacts with hot water
No change with beryllium and water

54. Transition Metals- White
Elements in groups 3-12
Less reactive, harder metals.
Includes metals used in jewelry and construction.
Most are hard and shiny.

55. Transition Metals- White

56. Boron Family- Light Green
Elements in group 13 (3A)
Aluminum:
Metal was once rare and expensive, not a “disposable metal.”
Most abundant metal in Earth’s crust
Less reactive than sodium and magnesium
strong, lightweight, malleable, and good conductor of electric current

57. Boron Family 3 valence electrons
Boron is used in glassware like flasks because it doesn’t shatter when it undergoes a rapid temperature change

58. Carbon Family- Red Elements in group 14 (4A)
Group 4A contains one nonmetal (C), 2 metalloids (Si, Ge), and 2 metals (Sn, Pb)
Contains elements important to life and computers.
Carbon is the basis for an entire branch of chemistry.
Coal and oil are mostly made of carbon.

59. Carbon Family 4 valence electrons
Metallic nature increases from top to bottom (Ge is better conductor than Si)
Life would not exist without carbon (except for water, most of the compounds in your body contain carbon)
Reactions in your body controlled by carbon compounds
Si is 2nd most abundant element in Earth’s crust (found in rocks, sand, and glass)

60. Nitrogen Family- Dark Blue
Elements in group 15 (5A)
Nitrogen makes up over ¾ of the atmosphere.
Nitrogen and phosphorus are both important in living things.
The red stuff on the tip of matches is phosphorus.

61. Nitrogen Family 5 valence electrons
2 nonmetals, 2 metalloids, and 1 metal
Contain a wide range of physical properties

62. Oxygen Family- Orange Elements in group 16 (6A)
Oxygen is necessary for respiration.
Many things that stink, contain sulfur (rotten eggs, garlic, skunks, etc.)

63. Oxygen Family 6 valence electrons 3 nonmetals and 2 metalloids
Oxygen is most abundant element in Earth’s crust
The 10 most abundant elements by mass in the earth's crust . All are main-group elements except iron and titanium.

64. Halogens- Purple Elements in group 17 (7A)
Very reactive, volatile, diatomic, nonmetals
Always found combined with other element in nature .
Used as disinfectants and to strengthen teeth.

65. The Halogens 7 valence electrons
Despite physical differences, the halogens have similar chemical properties
Highly reactive nonmetals, with fluorine being the most reactive and chlorine a close 2nd
React easily with most metals
Chlorine added to drinking water and swimming pools to kill bacteria

67. The Noble Gases- Dark Green
Elements in group 18 (8A)
VERY unreactive, monatomic gases
Used in blimps to fix the Hindenberg problem.
Have a full valence shell.

68. The Noble Gases 8 valence electrons Colorless and odorless
EXCEPTION is Helium, it has 2 valence electrons
Colorless and odorless
Used in lighted “neon” signs