The Modern Periodic TableThe Modern Periodic Table

Chapter 6Chapter 6

Objectives for Friday:Objectives for Friday:

4. Define period, group, and family. 4. Define period, group, and family. 5. Explain the different systems for 5. Explain the different systems for

numbering the groups on the numbering the groups on the Periodic table. Periodic table.

6. Name and locate on the periodic 6. Name and locate on the periodic table: metals, nonmetals, metalloids, table: metals, nonmetals, metalloids, noble gases, alkali metals, alkaline noble gases, alkali metals, alkaline earth metals, halogens, chalcogens, earth metals, halogens, chalcogens, Lanthanides, Actinides, Transition Lanthanides, Actinides, Transition metals, and Inner transition metals. metals, and Inner transition metals.

Objectives:Objectives: 7. Apply the octet rule in predicting the stability 7. Apply the octet rule in predicting the stability

of an element. of an element. 8. Predict the electron configuration of the outer 8. Predict the electron configuration of the outer

energy level of any element from its position on energy level of any element from its position on the Periodic table. the Periodic table.

9. Recognize exceptions to the Aufbau order due 9. Recognize exceptions to the Aufbau order due to half-full or full d-sublevels. to half-full or full d-sublevels.

10. Define atomic radius, ionic radius, ionization 10. Define atomic radius, ionic radius, ionization energy, electron affinity, and electronegativity. energy, electron affinity, and electronegativity.

11. Predict trends in atomic radius, ionic radius, 11. Predict trends in atomic radius, ionic radius, oxidation number, ionization energy, electron oxidation number, ionization energy, electron affinity, and electronegativity. affinity, and electronegativity.

12. Explain trends in terms of nuclear charge and 12. Explain trends in terms of nuclear charge and shielding effects. shielding effects.

Arrangement and Arrangement and NomenclatureNomenclature

Rows are called periodsRows are called periods Columns are designated as groupsColumns are designated as groups Each column in the main table and each Each column in the main table and each

row at the bottom is also designated an row at the bottom is also designated an individual familyindividual family

Groups 1A, 2A, and 3-8A are the main Groups 1A, 2A, and 3-8A are the main groups, or representative elementsgroups, or representative elements

Groups 1B-8B are called the transition Groups 1B-8B are called the transition elementselements

The Periodic Table With Atomic Symbols, Atomic The Periodic Table With Atomic Symbols, Atomic

Numbers, and Partial Electron ConfigurationsNumbers, and Partial Electron Configurations

Broad Periodic Table Broad Periodic Table ClassificationsClassifications

Representative ElementsRepresentative Elements (main (main group): filling group): filling ss and and pp orbitals (Na, Al, orbitals (Na, Al, Ne, O)Ne, O)

Transition ElementsTransition Elements: filling : filling dd orbitals (Fe, Co, Ni)orbitals (Fe, Co, Ni)

Lanthanide and Actinide SeriesLanthanide and Actinide Series (inner transition elements): filling (inner transition elements): filling 44ff and and 55ff orbitals (Eu, Am, Es)orbitals (Eu, Am, Es)

Information Contained in Information Contained in the Periodic Tablethe Periodic Table

1.1. Each group member has the Each group member has the same valence electron same valence electron configuration (these configuration (these electrons primarily determine electrons primarily determine an atom’s chemistry).an atom’s chemistry).

2.2. The electron configuration of The electron configuration of any representative element.any representative element.

Information Contained in Information Contained in the Periodic Tablethe Periodic Table

3.3. Certain groups have special Certain groups have special names (alkali metals, alkaline names (alkali metals, alkaline earth metals, chalcogens, earth metals, chalcogens, halogens, etc).halogens, etc).

4.4. Metals and nonmetals are Metals and nonmetals are characterized by their chemical characterized by their chemical and physical properties.and physical properties.

Special Names Special Names for Groups in for Groups in the Periodic the Periodic TableTable

MetalsMetals Metals makeup more than 75% of the Metals makeup more than 75% of the

elements in the periodic table. Metals are elements in the periodic table. Metals are characterized by the following physical characterized by the following physical properties:properties:– They have metallic shine or luster.They have metallic shine or luster.– They are usually solids at room temperature.They are usually solids at room temperature.– They are malleable. Malleable means that They are malleable. Malleable means that

metals can be hammered, pounded, or pressed metals can be hammered, pounded, or pressed into different shapes without breaking. into different shapes without breaking.

– They are ductile meaning that they can be They are ductile meaning that they can be drawn into thin sheets or wires without breaking. drawn into thin sheets or wires without breaking.

– They are good conductors of heat and electricity.They are good conductors of heat and electricity.

Metals (cont)Metals (cont) All B and most A elements are metals.All B and most A elements are metals. The B The B At stairstep designates the border At stairstep designates the border

between metals and non-metalsbetween metals and non-metals 1A elements are alkali metals1A elements are alkali metals

– They are soft shiny metals that usually They are soft shiny metals that usually combine with group VIIA nonmetals in chemical combine with group VIIA nonmetals in chemical compounds in a 1:1 ratio.compounds in a 1:1 ratio.

2A elements are the alkaline earth metals2A elements are the alkaline earth metals– Both alkali and alkaline earth metals are Both alkali and alkaline earth metals are

chemically reactive, but 2A metals are less chemically reactive, but 2A metals are less reactive than 1As.reactive than 1As.

– They combine with the group VIIA nonmetals in They combine with the group VIIA nonmetals in a 1:2 ratio.a 1:2 ratio.

Transition Metals & Transition Metals & MetalloidsMetalloids

Transition metalsTransition metals– The remaining 1-8B elements are all The remaining 1-8B elements are all

transition elementstransition elements– The transition elements also have The transition elements also have

valence electrons in two shells instead valence electrons in two shells instead of one.of one.

Inner transition metalsInner transition metals– The lanthanide and actinide series The lanthanide and actinide series

comprise the inner transition metalscomprise the inner transition metals

MetalloidsMetalloids

Metalloids have characteristics of Metalloids have characteristics of both metals and nonmetals and so both metals and nonmetals and so can’t be classified as either, but can’t be classified as either, but something in between.something in between.– They are good conductors of heat and They are good conductors of heat and

electricityelectricity– They are not good conductors or They are not good conductors or

insulators.insulators. The six metalloids are B, Si, Ge, As, The six metalloids are B, Si, Ge, As,

Sb, and Te. Sb, and Te.

NonmetalsNonmetals

There are 17 nonmetals in the periodic There are 17 nonmetals in the periodic table, and they are characterized by four table, and they are characterized by four major physical properties.major physical properties.– They rarely have metallic luster.They rarely have metallic luster.– They are usually gases at room temperature.They are usually gases at room temperature.– Nonmetallic solids are neither malleable nor Nonmetallic solids are neither malleable nor

ductile. ductile. – They are poor conductors of heat and electricity.They are poor conductors of heat and electricity.

The elements above the B The elements above the B At stairstep At stairstep are nonmetalsare nonmetals

Nonmetals (cont)Nonmetals (cont) Group 6A contains the chalcogen elementsGroup 6A contains the chalcogen elements Group 7A contains the highly reactive halogen Group 7A contains the highly reactive halogen

elementselements– They are fluorine, chlorine, bromine, and iodine. They are fluorine, chlorine, bromine, and iodine. – The halogens exist as diatomic molecules in nature.The halogens exist as diatomic molecules in nature.

Group 8A comprises the completely non-reactive Group 8A comprises the completely non-reactive noble gasesnoble gases– The noble gases are also called rare gas elements, and The noble gases are also called rare gas elements, and

they all occur in nature as gases. they all occur in nature as gases. – The noble gases fulfill the octet rule by having a full The noble gases fulfill the octet rule by having a full

outer level with 8 valence electrons. outer level with 8 valence electrons. – Therefore, they do not undergo chemical reactions Therefore, they do not undergo chemical reactions

because they do not accept any electrons.because they do not accept any electrons.

Valence Electrons and the Valence Electrons and the Periodic TablePeriodic Table

Valence Electrons and GroupValence Electrons and Group– Atoms in the same group have the same Atoms in the same group have the same

chemical properties because they have the chemical properties because they have the same number of valence electrons.same number of valence electrons.

– Moreover, they have the same outermost Moreover, they have the same outermost orbital structureorbital structure E.g. 1A elements all have sE.g. 1A elements all have s1 1 valence electronsvalence electrons E.g. 2A elements all have sE.g. 2A elements all have s22 valence electrons valence electrons

Valence Electrons and PeriodValence Electrons and Period– The primary quantum number (n) for an The primary quantum number (n) for an

element’s valence electrons is the same its element’s valence electrons is the same its period.period. E.g. Lithium’s valence electron is n=2 and Li is found E.g. Lithium’s valence electron is n=2 and Li is found

in the 2in the 2ndnd period period

The Octet RuleThe Octet Rule

Atoms tend to lose, gain, or share Atoms tend to lose, gain, or share electrons until they are surrounded electrons until they are surrounded by 8 valence electronsby 8 valence electrons

Exceptions to Aufbau OrderExceptions to Aufbau Order

Subshell degeneracies occur in Subshell degeneracies occur in elements larger than Vanadiumelements larger than Vanadium– i.e. different 4s and 3d orbitals have i.e. different 4s and 3d orbitals have

nearly the same energynearly the same energy Also, it turns out that full and half-full Also, it turns out that full and half-full

sublevels have the most stability.sublevels have the most stability.

Exceptions: Copper (Cu), Exceptions: Copper (Cu), Silver (Ag), Gold (Au)Silver (Ag), Gold (Au)

Strict Aufbau ordering of Cu would be Strict Aufbau ordering of Cu would be [Ar]4s[Ar]4s223d3d99 – experimental observation shows this to be an experimental observation shows this to be an

excited stateexcited state– the ground state has a configuration of [Ar]4sthe ground state has a configuration of [Ar]4s113d3d1010

The observed configuration for Cu creates a The observed configuration for Cu creates a ½-full s and a full d, which is more stable ½-full s and a full d, which is more stable than a full s and a partial dthan a full s and a partial d

Ag is NOT [Kr]5sAg is NOT [Kr]5s224d4d99, but [Kr]5s, but [Kr]5s114d4d1010

Au is NOT [Xe]6sAu is NOT [Xe]6s225d5d99, but [Kr]6s, but [Kr]6s115d5d1010

Exceptions: Lanthanum and Exceptions: Lanthanum and ActiniumActinium

Aufbau would place them in the inner Aufbau would place them in the inner transition series, but instead they are transition series, but instead they are in the scandium familyin the scandium family– i.e. La is [Xe]6si.e. La is [Xe]6s225d5d11 – i.e. Ac is [Rn]7si.e. Ac is [Rn]7s226d6d11

Exceptions: Exceptions: Chromium (Cr), Molybdenum Chromium (Cr), Molybdenum (Mo), but NOT Tungsten (W)(Mo), but NOT Tungsten (W)

Cr is [Ar]4sCr is [Ar]4s113d3d55, NOT [Ar]4s, NOT [Ar]4s223d3d44

Mo is [Kr]5sMo is [Kr]5s114d4d55, NOT [Kr]5s, NOT [Kr]5s224d4d44

W IS [Xe]6sW IS [Xe]6s115d5d55

Ionization EnergyIonization Energy

The quantity of energy The quantity of energy required to remove an required to remove an electron from the gaseous electron from the gaseous atom or ion.atom or ion.

For AluminumFor Aluminum

Al (g) AlAl (g) Al++ (g) + e (g) + e-- II11 = 580 kJ/mol = 580 kJ/mol

Al Al ++ (g) Al (g) Al2+2+ (g) + e (g) + e-- II22 = 1850 = 1850 kJ/molkJ/mol

AlAl2+2+ (g) Al (g) Al3+3+ (g) + e (g) + e-- II33 = 2740 = 2740 kJ/molkJ/mol

AlAl3+3+ (g) Al (g) Al4+4+ (g) + e (g) + e-- II44 = 11,600 = 11,600 kJ/molkJ/mol

Periodic TrendsPeriodic Trends

First ionization energyFirst ionization energy: : increasesincreases from left to right from left to right

across a across a periodperiod Why? Why?decreasesdecreases going down a going down a groupgroup. .

Why?Why?

Trends in Ionization Energies Trends in Ionization Energies for the Representative for the Representative

ElementsElements

The Values of First Ionization Energy The Values of First Ionization Energy for the Elements in the First Six for the Elements in the First Six

PeriodsPeriods

QuestionQuestion

The first ionization energy The first ionization energy for the group IIA elements are for the group IIA elements are significantly higher than significantly higher than those of the Group IA those of the Group IA elements in the same elements in the same periods. Why?periods. Why?

QuestionQuestion

The first ionization energy The first ionization energy of the Group IIIA elements are of the Group IIIA elements are lower than the IIA elements in lower than the IIA elements in the same period. Why?the same period. Why?

QuestionQuestion

Group VIA elements have Group VIA elements have slightly lower first ionization slightly lower first ionization energies than Group VA energies than Group VA elements in the same period. elements in the same period. Why?Why?

Electron AffinityElectron Affinity The energy change The energy change

associated with the addition associated with the addition of an electron to a gaseous of an electron to a gaseous atomatom..

X(X(gg) + e) + e X X((gg)) Note: the more negative Note: the more negative

the electron affinity, the the electron affinity, the more energy is releasedmore energy is released

The Electronic Affinity Values for The Electronic Affinity Values for Atoms Among the First 20 Elements Atoms Among the First 20 Elements that Form Stable, Isolated Xthat Form Stable, Isolated X-- Ions Ions

QuestionsQuestions Helium and Beryllium do not form Helium and Beryllium do not form

stable isolated negative ions. Why?stable isolated negative ions. Why?

Nitrogen does not form a stable, Nitrogen does not form a stable, isolated N- (g) ion, whereas carbon isolated N- (g) ion, whereas carbon forms C-(g). Why?forms C-(g). Why?

In contrast to nitrogen, oxygen can In contrast to nitrogen, oxygen can add an electron to form the stable O- add an electron to form the stable O- ion. Why?ion. Why?

Periodic TrendsPeriodic Trends

Atomic RadiiAtomic Radii:: decreasedecrease going from left to going from left to

right across a right across a periodperiod; Why?; Why?

increaseincrease going down a going down a groupgroup. Why?. Why?

The Radius of an AtomThe Radius of an Atom

Atomic Radii Atomic Radii for Selected for Selected AtomsAtoms

Ionic RadiiIonic Radii

What is the trend for ionic What is the trend for ionic radii?radii?

Which of the Period 3 ions Which of the Period 3 ions would be the smallest?would be the smallest?

NaNa++, Mg, Mg2+2+, Al, Al3+3+, S, S2-2-, Cl, Cl--

Sizes of Ions Related to Positions Sizes of Ions Related to Positions of the Elements in the Periodic of the Elements in the Periodic

TableTable

Electronegativity Increases Electronegativity Increases Up and To the RightUp and To the Right

What is electronegativity? How tightly an atom holds on to its

valence electrons. Essentially, this value depends on

– the number of positively charged protons in the atom’s nucleus

– the radius of the outermost electron shell

What is electronegativity? The more positive the nucleus The smaller the valence electron shell around it The greater the attraction between nucleus and

electrons Thus, the more electronegative the atom! Thus, a high electronegativity value implies that

the valence electrons are tightly held and require a large amount of energy to remove.

Oxidation NumbersOxidation Numbers The Octet Rule states that atoms want to The Octet Rule states that atoms want to

have their valence shell filled with have their valence shell filled with electrons.electrons.– This means that, ideally, atoms are most stable This means that, ideally, atoms are most stable

with 8 valence electrons with 8 valence electrons – N.B. This is not true for Period 1. Why?N.B. This is not true for Period 1. Why?

Atoms will gain or lose electrons to form Atoms will gain or lose electrons to form ions in order to fulfill the Octet Rule.ions in order to fulfill the Octet Rule.

The charge they take on in this process is The charge they take on in this process is called the valence.called the valence.

The oxidation state is, for ions, equal to The oxidation state is, for ions, equal to the valence.the valence.