1 Properties of Elements and TrendsThe 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 familiesHorizontal rows  called periods also represent the shells or energy levels The basis of periodic law is repeating patterns.

5 Major Categories of Elements1) 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

6

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-metalsCan 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 MetalloidsSolid 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 TableIn 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 LithiumCompounds 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 SodiumSodium 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 PotassiumThe 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 Alkaline Earth Metals (Group II)Have two valence electrons Tend to lose the two electrons to become a more stable ion

21 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

22 Magnesium

23 Applications of MagnesiumMagnesium 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

24 Calcium

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

26 Strontium

27 Applications of Strontiumfireworks (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

28 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

29 Fluorine

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

31 Chlorine

32 Chlorine Used in water purification and bleach.

33 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)

34 Argon

35 Argon                           Used in light bulbs and lasers.

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

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

38 Copper

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

40 Nickel

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

42 Silver

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

44 Lanthanide and Actinide SeriesRare earth metals Above 92 they are man-made and are unstable

45 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

46 bigger loser = more reactiveReactivity (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.

47 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.

48 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.

49 Non metallic CharacterRemember 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.

50 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.

51 Group Trends in Atomic RadiusAs 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.

52 Group Trends in Atomic RadiusAtomic Radius increases

53 Period Trends in Atomic RadiusAs 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.

54 Period Trends in Atomic RadiusAtomic radius decreases

55 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.

56 Group Trends in Ionization EnergyAs 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).

57 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.

58 Group Trends in Ionization EnergyFirst ionization energy decreases

59 Period Trends in Ionization EnergyAs 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.

60 Another Analogy: FootballIncreasing 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).

61 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.

62 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.

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

64 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.

65 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.

66 Cation Size MINUS ONE ELECTRONWhen 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

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

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

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

70 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

71 Trends in ElectronegativityIn 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).

72 Summary of Electronegativity TrendsElectronegativity Increases Electronegativity decreases

73 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.