Ch 7Ch 7

The Periodic TableThe Periodic Table

ObjectivesObjectives

SWBATSWBAT Define the periodic propertiesDefine the periodic properties Apply periodic trends to the periodic tableApply periodic trends to the periodic table

The Periodic TableThe Periodic Table

J.W. Dobereiner J.W. Dobereiner The elements in the triad has similar chemical The elements in the triad has similar chemical

properties. properties. Several elements could be classified into groups of Several elements could be classified into groups of

three called three called triadstriads. .

Jar Newlands Jar Newlands Arranged the elements in order of increasing Arranged the elements in order of increasing

mass.mass.

The Periodic TableThe Periodic Table

Dmitri Mendeleev Dmitri Mendeleev Organized the elements into the Periodic Table Organized the elements into the Periodic Table He started by sorting elements by increasing He started by sorting elements by increasing

mass. mass. He saw a repetition of pattern. He saw a repetition of pattern. Same column → same properties Same column → same properties Predicted the existence of new elements Predicted the existence of new elements

Henry Moseley Henry Moseley The atomic number is based on the amount of The atomic number is based on the amount of

positive charges in the nucleus. positive charges in the nucleus.

The Periodic LawThe Periodic Law

o When elements are arranged in order of When elements are arranged in order of increasing atomic number, their physical and increasing atomic number, their physical and chemical properties show a periodic pattern. chemical properties show a periodic pattern.

o Elements with similar properties are in Elements with similar properties are in vertical columns called vertical columns called Groups or FamiliesGroups or Families. .

o Horizontal rows are called Horizontal rows are called PeriodsPeriods. .

LabelingLabeling

European notation European notation American system American system IUPAC IUPAC

(Inter. Union of Pure (Inter. Union of Pure

& Applied Chemistry) & Applied Chemistry)

The elements in a group have similar The elements in a group have similar properties because they have valence properties because they have valence electrons in similar configurationselectrons in similar configurations

Roman numerals Roman numerals IA, IIA, IIIA IA, IIA, IIIA 1-18 (no letters)1-18 (no letters)

Valence ElectronsValence Electrons

Elements in the same column contain the Elements in the same column contain the same number of valence electrons same number of valence electrons (electrons in their outer-shell orbitals).(electrons in their outer-shell orbitals).

Atomic Radius (in a group)Atomic Radius (in a group)

Measure the atomic radius from the center of Measure the atomic radius from the center of the nucleus to the outermost electron. the nucleus to the outermost electron.

Atom size Atom size increasesincreases going down a group. going down a group. Reason: The principal quantum number of Reason: The principal quantum number of

the outermost (valence) electrons increases. the outermost (valence) electrons increases.

Atomic Radius (in a period)Atomic Radius (in a period)Atomic size Atomic size decreasesdecreases going across the period. going across the period.

Reason: Same principal quantum number going Reason: Same principal quantum number going across the period. across the period.

More protons are added going across the period. The More protons are added going across the period. The protons have a stronger pull on the electrons. The protons have a stronger pull on the electrons. The strong attractive forces between the protons and the strong attractive forces between the protons and the outermost (valence) electrons shrinks the orbitals outermost (valence) electrons shrinks the orbitals and makes the atoms smaller. and makes the atoms smaller. Generally speaking, Generally speaking, effective nuclear charge effective nuclear charge is the is the charge felt by the valence electrons after you have charge felt by the valence electrons after you have taken into account the number of shielding electrons taken into account the number of shielding electrons that surround the nucleus. Effective nuclear charge that surround the nucleus. Effective nuclear charge increases (which decreases shielding).increases (which decreases shielding).

Atomic RadiusAtomic Radius

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Ionic Size (when you create an ion)Ionic Size (when you create an ion) An ion is created when an atom gains or loses an An ion is created when an atom gains or loses an

electron.electron. 1)1) LOSE AN ELECTRON (create a positive ion) LOSE AN ELECTRON (create a positive ion)

Size becomes smaller Size becomes smaller Reason: Loss of an electron vacates outer orbitals Reason: Loss of an electron vacates outer orbitals

and reduces the repulsive forces between electrons. and reduces the repulsive forces between electrons.

2)2) GAIN AN ELECTRON (create a negative ion) GAIN AN ELECTRON (create a negative ion) Size becomes larger Size becomes larger Reason: There are a greater number of electrons. Reason: There are a greater number of electrons.

There is a greater repulsion force between electrons. There is a greater repulsion force between electrons. ***Elements in a group form ions of the same charge*** ***Elements in a group form ions of the same charge***

Left side of periodic table forms POSITIVE ions. Left side of periodic table forms POSITIVE ions. Right side of the periodic table form NEGATIVE Right side of the periodic table form NEGATIVE

ions.ions.

Ionization EnergyIonization Energy

This is the energy needed to remove the This is the energy needed to remove the outermost electron of an atom. outermost electron of an atom.

LiLi(g) (g) → Li→ Li++(g)(g)+ e+ e-- ionization energy 8.64 x 10 ionization energy 8.64 x 10-19-19 J/atomJ/atom

1)1) HIGHHIGH ionization energy means the atom hold ionization energy means the atom hold onto the electron tightly. onto the electron tightly.

2)2) LOWLOW ionization energy means the atom holds ionization energy means the atom holds onto the electron loosely. onto the electron loosely.

Since an atom is very small, scientists use a Since an atom is very small, scientists use a larger unit of measure called the mole. Therefore, larger unit of measure called the mole. Therefore, ionization energy is measured in J/molionization energy is measured in J/mol

Ionization Energy TrendIonization Energy Trend

1)1) Ionization energy Ionization energy decreasesdecreases as you as you move down a group. move down a group.

Reason: the electrons being Reason: the electrons being removed are, in general, farther from the removed are, in general, farther from the nucleus. As "n" increases, the size of the nucleus. As "n" increases, the size of the orbital increases, and the electron is orbital increases, and the electron is easier to remove.easier to remove.

(NOTE: This trend is the opposite of the atomic radius trend) (NOTE: This trend is the opposite of the atomic radius trend)

Ionization Energy TrendIonization Energy Trend

1)1) Ionization energy Ionization energy increasesincreases as you move as you move from left to right on the periodic table.from left to right on the periodic table.

Reason: electrons added in the Reason: electrons added in the same principal quantum level do not same principal quantum level do not completely shield the increasing nuclear completely shield the increasing nuclear charge caused by the added protons. charge caused by the added protons. The electrons in the same principal The electrons in the same principal quantum level are generally more quantum level are generally more strongly bound when moving left to right strongly bound when moving left to right across the periodic table across the periodic table

Ionization EnergyIonization Energy

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Successive IE’sSuccessive IE’s

The energy required to remove a second The energy required to remove a second electron from an atom is called its second electron from an atom is called its second IE, and so on…IE, and so on…

Electron Affinity (attraction)Electron Affinity (attraction)

This is the energy change that occurs when This is the energy change that occurs when a gaseous atom gains an extra electron.a gaseous atom gains an extra electron.

NeNe(g)(g) + e + e-- → Ne → Ne-1-1(g)(g) electron affinity= 29 kJ/mole electron affinity= 29 kJ/mole

If the electron affinity is a negative number, If the electron affinity is a negative number, the atom releases energy. the atom releases energy.

Normally, non-metals have a more negative Normally, non-metals have a more negative electron affinity than metals. The exception electron affinity than metals. The exception is the noble gases.is the noble gases.

Electron AffinityElectron Affinity Electron affinity generally becomes Electron affinity generally becomes

increasingly negative moving from left to increasingly negative moving from left to right. right.

(exception: the addition of an electron to a (exception: the addition of an electron to a noble gas would require the electron to noble gas would require the electron to reside in a new, higher-energy subshell. reside in a new, higher-energy subshell. Occupying a higher-energy subshell is Occupying a higher-energy subshell is energetically unfavorable, so the electron energetically unfavorable, so the electron affinity is positive, meaning that the ion will affinity is positive, meaning that the ion will not form)not form)

Electron AffinityElectron Affinity Electron affinity does not change greatly as we move Electron affinity does not change greatly as we move

down a group. Electron affinity should become more down a group. Electron affinity should become more positive (less energy released). positive (less energy released).

Reason:Reason: Moving down a group the average Moving down a group the average distance between the added electron and the nucleus distance between the added electron and the nucleus steadily increases, causing the electron-nucleus steadily increases, causing the electron-nucleus attraction to decrease. The orbital that holds the attraction to decrease. The orbital that holds the outermost electron is increasingly spread out, however, outermost electron is increasingly spread out, however, proceeding down the group, reduces the electron-proceeding down the group, reduces the electron-electron repulsions. A lower electron-nucleus attraction electron repulsions. A lower electron-nucleus attraction is thus counterbalanced by lower electron-electron is thus counterbalanced by lower electron-electron repulsions.repulsions.

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ElectronegativityElectronegativity

o This is the ability for an atom to attract an This is the ability for an atom to attract an electron in a chemical bond. electron in a chemical bond.

o The scale ranges from 0.7 to 4.0 The scale ranges from 0.7 to 4.0

o There are no units for this number. There are no units for this number.

METALS/NON-METALS/METALLOIDSMETALS/NON-METALS/METALLOIDS

The more an element exhibits the physical The more an element exhibits the physical and chemical properties of metals, the and chemical properties of metals, the greater its greater its metallic charactermetallic character..

Metallic character generally increases Metallic character generally increases going down a column and decreases going down a column and decreases going from left to right across a period going from left to right across a period

MetalsMetals Non-MetalsNon-Metals

Have a shiny luster; Have a shiny luster; various colors, although various colors, although most are silverymost are silvery

Do not have a luster; Do not have a luster; various colorsvarious colors

Solids are malleable and Solids are malleable and ductileductile

Solids are usually brittle; Solids are usually brittle; some are hard, and some some are hard, and some are softare soft

Good conductors of heat Good conductors of heat and electricityand electricity

Poor conductors of heat Poor conductors of heat and electricityand electricity

Most metal oxides are Most metal oxides are ionic solids that are ionic solids that are basicbasic

Most non-metallic oxides Most non-metallic oxides are molecular are molecular substances that form substances that form acidic solutionsacidic solutions

Tend for form cations in Tend for form cations in aqueous solutionsaqueous solutions

Tend to form anions or Tend to form anions or oxyanions in aqueous oxyanions in aqueous solutionsolution

METALSMETALS

Metals conduct heat and electricity. They Metals conduct heat and electricity. They are malleable (can be pounded into thin are malleable (can be pounded into thin sheets) and ductile (can be drawn into sheets) and ductile (can be drawn into wire).wire).

Metals are solids at room temperature Metals are solids at room temperature except Hg (which is a liquid)except Hg (which is a liquid)

METALSMETALS

Metals tend to have low ionization Metals tend to have low ionization energies and are consequently oxidized energies and are consequently oxidized (lose electrons) when they undergo (lose electrons) when they undergo chemical reaction.chemical reaction.

Many transition metals have the ability to Many transition metals have the ability to form more than one positive ion.form more than one positive ion.

Reactions with MetalsReactions with Metals

Metal oxide + water → metal Metal oxide + water → metal hydroxidehydroxide

Metal oxide + acid → salt + Metal oxide + acid → salt + waterwater

These reactions will be helpful to These reactions will be helpful to answer your Reaction Prediction answer your Reaction Prediction questions.questions.

Try Writing the ReactionTry Writing the Reaction

Sodium oxide is reacted with water.Sodium oxide is reacted with water.

Barium oxide is reacted with HCl.Barium oxide is reacted with HCl.

Reaction AnswersReaction Answers

Sodium oxide is reacted with water.Sodium oxide is reacted with water.

NaNa22O + HO + H22O O NaOH NaOH

Barium oxide is reacted with HCl.Barium oxide is reacted with HCl.

BaO + HCl BaO + HCl BaCl BaCl22 + H + H22OO

Non-MetalsNon-Metals

Non-metals are not lustrous and are poor Non-metals are not lustrous and are poor conductors of heat and electricity.conductors of heat and electricity.

Non-metals commonly gain enough Non-metals commonly gain enough electrons to fill their outer p sub-shell electrons to fill their outer p sub-shell completely, giving a noble gas electron completely, giving a noble gas electron configuration.configuration.

Compounds composed entirely of Compounds composed entirely of nonmetals are called molecular nonmetals are called molecular substances.substances.

Non-Metal ReactionsNon-Metal Reactions

Nonmetal oxide + water → acidNonmetal oxide + water → acid

Nonmetal oxide + base → salt + waterNonmetal oxide + base → salt + water

These reactions will be helpful to answer These reactions will be helpful to answer your Reaction Prediction questions.your Reaction Prediction questions.

Try these Reactions.Try these Reactions.Carbon dioxide reacts with water.Carbon dioxide reacts with water.

Tetraphosphorous decaoxide reacts with Tetraphosphorous decaoxide reacts with water.water.

Sulfur trioxide reacts with barium hydroxide.Sulfur trioxide reacts with barium hydroxide.

Tetraphosphorous decaoxide reacts with Tetraphosphorous decaoxide reacts with sodium hydroxide.sodium hydroxide.

Reaction AnswersReaction AnswersNonmetal oxide + water → acidNonmetal oxide + water → acid

COCO22 (g) + H (g) + H22O(l) ---> HO(l) ---> H22COCO33 (aq) (aq)

PP44OO1010 (s) + 6 H (s) + 6 H22O(l) ---> 4 HO(l) ---> 4 H33POPO44 (aq) (aq)

Nonmetal oxide + base → salt + waterNonmetal oxide + base → salt + water SOSO3(g)3(g) + Ba(OH) + Ba(OH)2(aq)2(aq) → BaSO → BaSO4(aq)4(aq) + H + H22OO(l)(l)

PP44OO10(s)10(s) + 12 NaOH + 12 NaOH(aq)(aq) → 4 Na → 4 Na33POPO4(aq)4(aq) + 6 H + 6 H22OO(l)(l)

MetalloidsMetalloids

Metalloids have properties between those Metalloids have properties between those of metals and nonmetals.of metals and nonmetals.

Metalloids are also called semi-metals.Metalloids are also called semi-metals.

Group NamesGroup Names

Know the group (family) names:Know the group (family) names:

Alkali metalsAlkali metals Alkaline earth metalsAlkaline earth metals HalogensHalogens Noble gasesNoble gases

Alkali MetalsAlkali Metals

SoftSoft Metallic lusterMetallic luster High thermal and electrical High thermal and electrical

conductivityconductivity Low densitiesLow densities Low melting pointsLow melting points Exist in nature as compoundsExist in nature as compounds

Alkaline Earth MetalsAlkaline Earth Metals

SolidsSolids Harder than alkali metalsHarder than alkali metals More dense than alkali metalsMore dense than alkali metals Higher melting points than alkali Higher melting points than alkali

metalsmetals

Homework ProblemsHomework Problems

4, 5, 9, 11, 13-17, 20, 23, 24, 27, 28, 4, 5, 9, 11, 13-17, 20, 23, 24, 27, 28, 32, 33, 35, 38, 40, 39, 41, 43, 45, 49, 32, 33, 35, 38, 40, 39, 41, 43, 45, 49, 5454

Do 40 before 39Do 40 before 39