Chapter 5

In a nutshell

Key Players• Dmitri Mendeleev- father of periodic table;

arranged elements in order of increasing atomic mass.

• Henry Mosley- creator of the MODERN periodic table; arranged elements in order of increasing atomic numbers (# of protons in nucleus)

Vocabulary• Periodic law- the physical and chemical

properties of the elements are periodic functions of their atomic numbers.

• Or… when the elements are arranged in order of increasing atomic number elements with similar properties appear at regular intervals.

• Periodic Table- an arrangement of the elements in order of their atomic numbers so that elements with similar properties fall in the same column, or group.

Noble gasses

• Group 18

• Non reactive

• All gasses

• 8 valence electrons

Section 2

Periods• How many energy levels does Lithium (3)

have?

• 2

• How many energy levels does Arsenic (33) have?

• 4

• How many energy levels does Radium (88) have?

• 7

Blocks• S block

• P block

• D block

• F block

S Block elements• Group one = alkali metals

• Soft; silvery appearance; VERY reactive; not found in nature except in compounds

• React vigorously with water to produce hydrogen gas and aqueous solutions of alkalis

• Group two = alkaline-earth metals

• Harder denser and stronger than alkali metals

• Higher melting points than alkali metals

• Less reactive than alkali metals but are still not found in nature unless in compounds

Hydrogen and Helium

• Hydrogen and helium are exceptions to many rules.

• Know their electron configurations and learn when they apply to the rules and when they don’t.

Practice• 3s^1• Na (11)• 2p^3• N (7)• 6d^4• W (74)• 5p^2• Sn (50)• 3d^6• Fe (26)

• 4s^2• Ca (20)• 1s^2• He (2)• 5d^9• Ag (47)• 6p^2• Pb (82)• 3p^5• Cl (17)

D-block Elements• Transition elements

• Elements with typical metallic properties

• Good conductors of electricity

• Have high luster

• Typically less reactive than s-block elements.

• Some are so unreactive that some can stand alone in nature (palladium, platinum, and gold)

P-block elements• Consists of all the elements of groups 13-18

except helium.

• P block elements with the s-block elements are called the main-group elements or representative elements.

• Page 136

F-block

• Page 138

Quiz1) Creator of the modern periodic

table?

2) React vigorously with water to produce hydrogen gas and aqueous solutions of alkalis

3) Some are so unreactive that some can stand alone in nature (palladium, platinum, and gold)

4) 5d^9

5) Consists of all the elements of groups 13-18 except helium

1) Mosley

2) Alkali Metals

3) Transition metals or d-block elements

4) Silver (Ag)

5) p-block elements

Section 3Section 3

Electron configuration and periodic Electron configuration and periodic properties.properties.

Atomic radiiAtomic radiiYou would think that the atomic radii would be You would think that the atomic radii would be

measured from the center of the nucleous to measured from the center of the nucleous to the outer edge of the electron cloud.the outer edge of the electron cloud.

But the electron cloud edge is fuzzy and But the electron cloud edge is fuzzy and indistinct, so it’s hard to find an accurate indistinct, so it’s hard to find an accurate measurement.measurement.

SoSoAtomic RadiusAtomic Radius- one-half the distance between - one-half the distance between

the nucei of identical atoms that are bonded the nucei of identical atoms that are bonded together.together.

Period trendsPeriod trendsThere is a gradual decrease in atomic radii There is a gradual decrease in atomic radii

across the second period from lithium to neon.across the second period from lithium to neon.This is caused by the increasing positive This is caused by the increasing positive

charge of the nucleous.charge of the nucleous.The increased pull on the electrons results in The increased pull on the electrons results in

the decrease in atomic radii.the decrease in atomic radii.As you move down a group, the atomic radii As you move down a group, the atomic radii

tend to increase. tend to increase. This is because of more energy levelsThis is because of more energy levels

Ionization energyIonization energyAn electron can be removed from an atom if An electron can be removed from an atom if

enough energy is supplied.enough energy is supplied.A + energy A + energy (A+) + e- (A+) + e-A = atom…… A+ = an ion of an element with a A = atom…… A+ = an ion of an element with a

single positive charge. (a 1+ ion)single positive charge. (a 1+ ion) IonIon- an atom or group of bonded atoms that has - an atom or group of bonded atoms that has

a positive or negative charge.a positive or negative charge. IonizationIonization- any process that results in the - any process that results in the

formation of an ion.formation of an ion.

Ionization energyIonization energy- the energy required to - the energy required to remove one electron from a neutral atom of an remove one electron from a neutral atom of an element.element.

IE or first ionization energy (IEIE or first ionization energy (IE11))Period trends:Period trends: IN GENERAL ionization energies of the main IN GENERAL ionization energies of the main

group elements increase across each period.group elements increase across each period.Group trends:Group trends: Ionization generally decrease as you move Ionization generally decrease as you move

down a group.down a group.This is why elements tend to be more reactive This is why elements tend to be more reactive

as you move down the table.as you move down the table.

Electron AffinityElectron AffinityElectron AffinityElectron Affinity- the energy that occurs when - the energy that occurs when

an electron is acquired by a neutral atom.an electron is acquired by a neutral atom.most atoms release energy when they acquire most atoms release energy when they acquire

an electron. an electron. A + e- A + e- (A-) + energy … the quantity of (A-) + energy … the quantity of

energy released is expressed as a negative energy released is expressed as a negative numbernumber

Some atoms must be forced to gain an electron Some atoms must be forced to gain an electron by the addition of energy.by the addition of energy.

A + e- + energy A + e- + energy A- … the quantity of energy A- … the quantity of energy absorbed is represented as a positive number.absorbed is represented as a positive number.

Period trendsPeriod trends In general, electron affinities become more In general, electron affinities become more

negative across the p-block.negative across the p-block.With the exception of groups 14 and 15.With the exception of groups 14 and 15.Group TrendsGroup TrendsGroup trends of electron affinities are not as Group trends of electron affinities are not as

regular as many other characteristics.regular as many other characteristics.

ElectronegativityElectronegativity Valence electrons hold atoms together in chem Valence electrons hold atoms together in chem

compounds.compounds. In many compounds the negative charge of the In many compounds the negative charge of the

valence electrons is concentrated closer to one atom valence electrons is concentrated closer to one atom than the other.than the other.

ElectronegativityElectronegativity- a measure of the ability of an atom - a measure of the ability of an atom in a chemical compound to attract electrons.in a chemical compound to attract electrons.

The most elecronegative element, flourine, is The most elecronegative element, flourine, is arbitrarily assigned an electronegativity value of four.arbitrarily assigned an electronegativity value of four.The values of the other elements are calculated in The values of the other elements are calculated in realtion to this value.realtion to this value.

Period TrendsPeriod TrendsElectronegativites tend to increase across each Electronegativites tend to increase across each

period, although there are exceptions.period, although there are exceptions.Alkali and alkaline-earth metals are the least Alkali and alkaline-earth metals are the least

electronegative elements.electronegative elements.Nitrogen, oxygen, and the halogens are the Nitrogen, oxygen, and the halogens are the

most electronegative elements.most electronegative elements.Group trendsGroup trendsElectronegativities tend to either decrease Electronegativities tend to either decrease

down a group or stay about the same.down a group or stay about the same.

Quiz For a Test GradeQuiz For a Test Grade1)1) one-half the distance one-half the distance

between the nucei of between the nucei of identical atoms that are identical atoms that are bonded together.bonded together.

2)2) As you move down a group, As you move down a group, the atomic radii tend the atomic radii tend to_________to_________

3)3) any process that results in any process that results in the formation of an ion is the formation of an ion is called ________called ________

4)4) ionization energy is ionization energy is abbreviated _______abbreviated _______

5)5) the energy that occurs the energy that occurs when an electron is when an electron is acquired by a neutral atom acquired by a neutral atom is called electron ______is called electron ______

1)1) Atomic radiusAtomic radius

2)2) IncreaseIncrease

3)3) IonizationIonization

4)4) IEIE

5)5) AffinityAffinity