1. Properties of Elements and Trends
The Periodic Table
Properties of Elements and Trends

2. Mendeleev The original periodic table was created by Dmitri Mendeleev.
He organized the table by atomic mass.
He predicted existence of 3 missing elements (Ga, Sc, Ge)

3. Modern Periodic Table
The modern periodic table is organized by atomic number.
Henry Mosely

4. Vertical columns  called groups or families
Horizontal rows  called periods also represent the shells or energy levels
The basis of periodic law is repeating patterns.

5. Major Categories of Elements
1) metals 2) non-metals 3) metalloids
Metals are found to the left of the “staircase”
Non-metals are found to the right of “staircase”
Metalloids are found “on” the staircase

7. Properties of Metals Solid at room temperature (except Hg)
Shiny, Have luster
Malleable
Ductile
Generally have high melting points
Good conductor of heat and electricity
Have metallic bonds

8. Properties of Non-metals
Can be solid, liquid or gas at room temp
S  examples C, S, I2
L  Br2
G  O2, Ne, F2
Allotropes- different molecular forms of the same element (different properties, too) O2 and O3
Dull, lack luster
Brittle
Poor conductors

9. Properties of Metalloids
Solid at room temperature
Semi-conductors
Have varying properties that can be metallic or non-metallic

10. Metals tend to lose electrons to form a full valence shell and + ions.
Non-metals tend to gain electrons to form a full valence shell and – ions.

11. Groups on the Periodic Table
In general, elements found within the same group have similar chemical and physical properties.
This is mainly due to the fact that they have the same number of valence electrons.

12. Alkali Metals (Group I)
Have one valence electron
Tend to lose that one electron to become a more stable ion.
Rarely found in natural state.

13. Lithium(Li), Sodium(Na), and Potassium(K)
Three examples of alkali metals
VERY reactive metals
Exist as solids at room temperature, but are soft
Silvery-white or grayish in color

14. Lithium

15. Applications of Lithium
Compounds containing Li have many applications:
lithium hydroxide is used to absorb carbon dioxide in space vehicles
lithium is used in the manufacture of special high strength glasses and ceramics
sometimes, lithium-based compounds such as lithium carbonate (Li2CO3) are used as drugs to treat manic-depressive disorders.

16. Sodium

17. Applications of Sodium
Sodium compounds include:
"common salt" (sodium chloride, NaCl),
"soda ash" (sodium carbonate, Na2CO3)
"baking soda" (sodium bicarbonate, NaHCO3)
"caustic soda" (sodium hydroxide, NaOH), are important to the paper, glass, soap, textile, petroleum, chemical, and metal industries
sodium vapor is used in lamps for street lighting

18. Potassium

19. Applications of Potassium
The metal is the seventh most abundant and makes up about 1.5 % by weight of the earth's crust.
Potassium is an essential constituent for plant growth and it is found in most soils.
It is also a vital element in the human diet.

20. Comparing 3 Alkali Metals
Lithium
Potassium
Sodium

27. Alkaline Earth Metals (Group II)
Have two valence electrons
Tend to lose the two electrons to become a more stable ion

28. Magnesium(Mg), Calcium(Ca) and Strontium(Sr)
Examples of alkaline earth metals
Exist as solids at room temperature
Silvery white or grayish white in color
Fairly reactive metals

29. Magnesium

30. Applications of Magnesium
Magnesium is the eighth most abundant element in the earth's crust although not found in it's elemental form.
used in flares and pyrotechnics
it is lighter than aluminum, and is used in alloys used for aircraft, car engine casings, and missile construction

31. Calcium

32. Applications of Calcium
Forms more than 3% of the earth’s crust
Is an essential constituent of leaves, bones, teeth, and shells
is a component of Portland cement

33. Strontium

34. Applications of Strontium
fireworks (red flame), flares
90Sr is a radioactive isotope produced by nuclear fallout. 90Sr has the potential for use as lightweight nuclear producing electricity
used to produce glass for color television tubes

35. Halogens Group 17 Have 7 valence electrons Non-metals (F, Cl, Br, I)
F, Cl (gases), Br (liquid), I (solid)
Tend to gain one electron to form a more stable ion
Extremely reactive

36. Fluorine

37. Fluorine
Used as a toothpaste additive, in refrigerator coolants, and in Teflon

38. Chlorine

39. Chlorine
Used in water purification and bleach.

40. Noble Gases Group 18 Very stable because of filled valence shell.
Do not react in the presence of other elements (relatively inert)
Xe can react with Fluorine (more later)

41. Argon

42. Argon
                         
Used in light bulbs and lasers.

43. Xenon
Used in UV lamps and sun lamps in tanning salons.

44. Transition Metals Also known as “heavy metals” Tend to be very dense
Have varying reactivity
Have multiple oxidation states (can form more than one ion)
Have colorful ions (in solution)

45. Copper

46. Copper
Used to make the Statue of Liberty, pennies, water pipes and more.

47. Nickel

48. Nickel
Used to make coins, knives, forks and rechargeable batteries.

49. Silver

50. Silver
Used in silverware, jewelry, mirrors, and batteries.

51. Lanthanide and Actinide Series
Rare earth metals
Above 92 they are man-made and are unstable

52. Periodic Trends
Trends occur in the periodic table in the following areas:
-reactivity
-metallic/non-metallic character
-atomic radius*
-ionization energy*
-ionic radius
-electronegativity*
* Found on Table S

53. bigger loser = more reactive
Reactivity (metals)
Atoms react when they gain, lose or share electrons (bonding).
Metals – lose e-,
bigger loser = more reactive
Across a period, metal reactivity decreases.
Down a group, metal reactivity increases.

54. Reactivity (non metals)
Atoms react when they gain, lose or share electrons (bonding).
non metals – gain e-,
Better gainer = more reactive
Across a period, non metal reactivity increases.
Down a group, non metal reactivity decreases.

55. Metallic Character Remember best metal is Francium (lower left)
Metallic character is relative to Fr.
Across a period (away from Fr) metallic character decreases.
Down a group (towards Fr) metallic character increases.

56. Non metallic Character
Remember best non metal is Fluorine (upper right)
Non metallic character is relative to F.
Across a period (towards F) non metallic character increases.
Down a group (away from F) non metallic character decreases.

57. Atomic Radius Atomic radius provides a basis for the size of an atom.
Atomic radius is equal to half the distance between 2 neighboring nuclei of the same element.

58. Group Trends in Atomic Radius
As you move down a group in the periodic table, atomic radius generally increases.
This is due to the fact that as you move down a column the number of shells increases making the atom bigger.

59. Group Trends in Atomic Radius
Atomic Radius increases

60. Period Trends in Atomic Radius
As one moves across a period of the Periodic Table, atomic radius generally decreases.
This is due to the fact that each successive element has one more proton that increases the nuclear charge. This positive charge pulls on the outermost shell and makes the atom smaller.

61. Period Trends in Atomic Radius
Atomic radius decreases

62. Ionization Energy
The energy required to remove an electron from an atom is known as the FIRST IONIZATION ENERGY.
To remove a second electron requires what is called the SECOND IONIZATION ENERGY.

63. Group Trends in Ionization Energy
As one moves down a group, first ionization energy generally decreases.
This is due to the fact that as one moves down a group the atomic size increases and outermost e- further away from the nucleus (the nucleus doesn’t have as much pull so it takes less energy to remove).

64. An Analogy: Football
Remember, as atomic size increases, the outermost electrons become further away from the nucleus.
If a football player is holding the ball very close to himself, it is more difficult to remove it from him.
If a football player is holding the ball far away from his body is becomes much easier (less energy) to remove it.

65. Group Trends in Ionization Energy
First ionization energy decreases

66. Period Trends in Ionization Energy
As one moves across a period of the Periodic Table, first ionization energy generally increases.
This is due the fact that as atomic number (number of protons) increases, so does nuclear charge.
The stronger nuclear charge makes it more difficult to remove an electron.

67. Another Analogy: Football
Increasing atomic number and therefore nuclear charge would be analogous to the football player building strength.
It then becomes more difficult to get the ball from him (ionization energy increases).

68. Stop and Practice
How would you describe the atomic radius of a period-2 alkaline earth metal with that of a period-4 alkaline earth metal?
Answer: The atomic radius of a period-2 alkaline earth metal is smaller than that of a period-4 alkaline earth metal.

69. More practice
Which has a larger atomic radius within the same period: a halogen or an alkali metal?
Answer: An alkali metal has a larger atomic radius than a halogen within the same period.

70. More Practice
Which element in group 16 has the highest first ionization energy? In period 2?
Answer: Oxygen and neon

71. Ion Formation
Atoms with low ionization energies (they lose electrons easily) form positive ions (CATIONS). Metals do this.
Atoms with high ionization energies tend to gain electrons to form negative ions (ANIONS). Non-metals do this.

72. Ionic Size (Cations)
The gaining or loss of an electron affects the size of atom (that turns into an ion).
Positive ions are smaller than the atom they are made from.

73. Cation Size MINUS ONE ELECTRON
When an electron is lost from an atom, the nucleus now has more pull on the outer energy level making the ion SMALLER.
MINUS ONE ELECTRON

74. Ionic Size (Anions)
Negative ions are larger than the atom they are made from.

75. Anion Size PLUS ONE ELECTRON
When an electron is gained the nucleus now has less pull on the outer energy level making the ion LARGER.
PLUS ONE ELECTRON

76. Trends in Ionic Radius (Both Cations and Anions)
Ionic Radius decreases
Ionic Radius increases

77. Electronegativity
Can be defined as an atom’s ability to attract electrons.
Expressed in arbitrary units on Table S of your Reference Tables.
Non-metals tend to have higher electronegativities because they like to gain electrons.
atoms
electrons

78. Trends in Electronegativity
In one sentence
THE CLOSER AN ATOM IS TO FLUORINE ON THE PERIODIC TABLE, THE HIGHER THE ELECTRONEGATIVITY.
** Fluorine has the highest electronegativity on the Periodic Table (4.0).

79. Summary of Electronegativity Trends
Electronegativity Increases
Electronegativity decreases

80. Stop and Practice
How does the ionic radius of sodium compare with that of cesium? Boron with fluorine?
Answer: Sodium is smaller than cesium. Boron is larger than fluorine.