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Chapter-5

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The Periodic Table

Chapter 5

Chapter-5 2

Chapter-5 3

Periodic Poem

Each element has a spot on the Periodic Table,

Whether metal or gas, radioactive or stable.

You can find out its number, its symbol, its weight,

And from its position, its physical state.

Elements lined up in columns and rows,

The reason for this order, as each chemist knows,

Is that atoms are made up of still smaller bits,

(Figuring this out tested scientists' wits!).

In the nucleus, protons and neutrons are found,

And a cloud of electrons is buzzing around.

First take one proton, put in its place;

Now you have hydrogen, the simplest case.

Add two neutrons and one more proton,

And suddenly, the hydrogen's gone!

Now you have helium, quite different stuff ...

You get the picture; I've said enough.

These tiny particles: they're like building blocks

That make people and buildings, flowers, and rocks.

They create all of the elements we find

In everyday things of every kind!

Chapter-5 4

1789 - Lavoisier

Acid making

phosphorous

sulfur

carbon

Gas like

light

heat

oxygen

Azote (nitrogen)

hydrogen

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1789 - Lavoisier

Metallic

Copper, nickel, iron

Cobalt, mercury, tin

Gold, lead, silver, zinc

Earthy

Lime (calcium hydroxide)

Magnesia (magnesium oxide)

Manganese, tungsten

(platina) platinum

Barytes (barium sulphate)

Argilla (Aluminum oxide)

Silex (silicon dioxide)

Chapter-5 6

Development of the Modern Periodic Table

1. Compiled a list of 23 elements known at the time.

2. 1800’s changes in the world

3. Electricity to break compounds, spectrometer, industrial revolution

4. Tripled Lavoisier’s number of elements

5. 1860 chemists agreed on atomic masses

A. Lavoisier – 1790’s

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Chapter-5 7

B. John Newland - 1864

1. Proposed an organization scheme

2. Arranged by increasing atomic mass

3. The elements properties repeated every eighthelement

4. The law of octaves.

John Newlands arranged the first 16 known elements and called it “ Law of Octaves”.

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Chapter-5 9

Stanislao Cannizzaro: proposed method to measure standard relative atomic masses

In 1869, Dmitri Mendeleev and Lothar Meyerindependently proposed the Periodic Law:

• Meyer based his periodic law on the property called atomic volume:

The periodic law states that when the elements are arranged in the order of increasing atomic mass, their physical and chemical properties vary periodically.

Atomic volume (cm3/mol) =Molar mass (g/mol)

d (cm3/g)

C. Cannizzaro, Meyer, Mendeleev

Chapter-5 10

C. Cannizzaro, Meyer, Mendeleev

Meyer & Mendeleev each demonstrated connections between atomic mass and elemental properties.

Mendeleev published first and showed the connections usefulness.

Mendeleev arranged the PT using atomic mass and their physical and chemical properties.

He predicted the existence and properties of undiscovered elements.

He left blanks for undiscovered elements. Can you find errors in his system?

Chapter-5 11

Based on Atomic Mass

Chapter-5 12

Mendeleev’s First Periodic Table

"I saw in a dream a table where all elements fell into place as required. Awakening, I immediately wrote it down on a piece of paper, only in one place did a correction later seem necessary."— Mendeleev, as quoted by Inostrantze

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Chapter-5 13

British chemist - discoveries resulted in a more accurate positioning of elements by determination of atomic numbers.

(Tragically for the development of science, Moseley was killed in action at Gallipoli in 1915).

D. Henry Moseley, 1913

Chapter-5 14

When atoms were arranged according toincreasing atomic number, the few problems with Mendeleev's periodic table had disappeared. Because of Moseley's work, the modern periodic table is based on the atomic numbers of the elements

Periodic Law: There is a periodic repetition of the chemical and physical properties of the elements when they are arranged by increasing atomic number.

D. Henry Moseley, 1913

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E. William Ramsay

Mendeleev did not anticipate the noble gases. He left no blanks for them.

William Ramsay discovered them.

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QUESTION:

Are there other periodic tables ?

Try to find:Carbon

Chapter-5 17 Chapter-5 18

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Chapter-5 23

How Diverse is Our Periodic Table?

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Periodic Table Song:https://www.youtube.com/watch?v=zUDDiWtFtEM

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Chapter-5 25

7 periods → arranged in order of increasing atomic number18 groups → each group has similar properties

Groups (vertical)Periods(horizontal)

Periodic Table of the ElementsBased on Atomic Numbers1

2

3

4

5

6

7

Chapter-5 26

Valence Electrons

1. electrons in the highest principal energy level

2. What would group IA look like?

3. Atoms in the same group have similar chemical properties because they have the same number of valence electrons.

The s-, p-, d- and f- block elements

1s1, 2s1….

Classification of the Elements

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Classification of the Elements

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For convenience f-block elements are pulled out of the 6th and 7th period.

If f-block Elements were in 6th and 7th Periods

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Metal –Metalloid – Nonmetal

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Elements in Our Daily Life

Solids:

• Carbon, sulfur

• Copper, iron, gold

Liquids: There are only 2 liquids at room temperature!

• Mercury

• Bromine

Gases:

• Oxygen, hydrogen, nitrogen

• Argon, neon, helium

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Chapter-5 31

Main Group elements

Inner-transitionelements

Transition elements

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s and p block elements are known as Main Group Elements

The electron configurations of the elements in each main group are regular and consistent: same group elements have same number of valence electrons.

•Group-1 : 1 valence e–



Chapter-5 33

Alkali Metals

Transition Metals

Alkaline-Earth Metals Halogens

Noble Gases

Lanthanides and Actinides

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Your Turn: Label all groups on the Periodic Table

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KEY

HydrogenMetalloids

Chapter-5 36

Properties of Metals, Metalloids and Nonmetals

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Chapter-5 37

Properties of Metals

Metals are:

•Good conductors of heat and electricity

•Malleable

•Ductile

•High luster

•All solids except mercury

•High tensile strength

•

Chapter-5 38

Properties of Metalloids

Metalloids have properties of both metals and nonmetals!

They are:

• More brittle than metals but less brittle than most nonmetallic solids

• Semiconductors of electricity

• Some posses metallic luster

Chapter-5 39

Silicon – A Metalloid

Other metalloids include:

Boron, B Germanium, GeArsenic, AsAntimony, Sb Tellurium, Te

metallic lusterbrittle like a nonmetala semiconductor

Chapter-5 40

Properties of Nonmetals

Nonmetals are:

• Poor conductors of heat and electricity

• Tend to be brittle

• Solid, liquid (Br2) but mostly gases at room temp.

Carbon, the graphite in “pencil lead” is a great example of a nonmetallic element.

Chapter-5 41

Other Nonmetals

Sulfur, S, was once known as “brimstone”

Microspheres of phosphorus, P, a reactive nonmetal

Graphite is not the only pure form of carbon, C. Diamond is also carbon; the color comes from impurities caught within the crystal structure

Chapter-5 42

s-block Elements: Group 1A & 2A

Chemically reactive metals, group 1 more reactive than group 2

•Has one valance electron, thus extremely reactive!

Alkali metals:

• Silvery appearance

• Soft enough to cut with a knife

• NOT found in nature as free elements

• Typically have lower mp than transition metals

• Hydrogen shares e-configuration but NOT the properties

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Chapter-5 43

s-block Elements: Group 1A

Li Na K

Reactivity of Alkali Metals Chapter-5 44


Alkaline-earth metals:

• Has two valence electrons, thus very reactive

• Harder, denser, stronger than group-1

• Have a higher melting point than group-1

• Too reactive to be found uncombined in nature

• Helium shares e- configuration but NOT properties

Chapter-5 45


Alkaline-earth metals:

• The word “alkaline” means “basic”➢ Common bases include salts of metals:

NaOHCa(OH)2

Mg(OH)2

Ca(OH)2

Mg(OH)2

Chapter-5 46

p-block Elements: Group 13A-18A

Includes:

metals, metalloids, and nonmetals

Noble Gases: least reactiveHalogens: most reactive nonmetals• Vigorous reaction with most metals to form salt• Halogen means “salt maker” in ancient Greek

Chapter-5 47

p-block Metals: Group 13A-16A

p-block metals are generally:•harder & denser than s-block•but softer & less dense than d-block metalsFound in nature solely as compounds except for bismuth

Chapter-5 48

p-block Metalloids: Group 13A-16A

Metalloids have properties of both metals and nonmetals!

They are:

• More brittle than metals but less brittle than most nonmetallic solids

• Semiconductors of electricity

•Some posses metallic luster

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Chapter-5 49

p-block Nonmetals: Group 13A-18A

Sulfur Phosphorous

Carbon

Iodine

yellow red violet black

White phosphorus, or yellow phosphorus (P4)White phosphorus is a translucent waxy solid that quickly becomes yellow when exposed to light

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p-block Nonmetals: Group 17A

Cl2 Br2 I2

Br2

Cl2

I2

F2 is a highly reactive and toxic gas

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Halogens: Group 17A

Halogens:•have 7 valence electrons•are never found pure in nature; they are too reactive!

•in their pure form are diatomic molecules: (F2, Cl2, Br2, and I2)• F2: pale-yellow gas• Cl2: yellow-green gas• Br2: brown liquid (with brown vapor)• I2: metallic solid (with purple vapor)

Chapter-5 52

Noble Gases: Group 18A

have 8 valence electrons (except Helium 2e- )are monoatomic gases ONLY found pure in nature.colorless, odorless and unreactive; they were among the last of the natural elements to be discoveredhave astronomical ionization energieshave positive electron affinities•Because, they are relatively unreactive!

Chapter-5 53

Noble Gas Compounds?

Xe forms three compounds:

•XeF2

•XeF4 (at right)

•XeF6

Kr forms only one stable compound:•KrF2

The unstable HArF was synthesized in 2000.

Crystals of XeF4

Chapter-5 54

d-block elements: Group 3B-12B

Transition Metals

Copper, Cu, is a relatively soft metal, and a very good electrical conductor.

Mercury, Hg, is the only metal that exists as a liquid at room temperature

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d-block elements: Group 3B-12B

Transition Metals:Less reactive than s block, many existing in nature as free elements.Electrons added to the d sublevel of the preceding energy level (n-1).

Electron configuration: (n-1) d1-10 ns 0-2

Some deviations from orderly d sublevel filling occur in group 4-11(s electrons jumping to d sublevel)They often form colored compounds and have multiple oxidation states

Chapter-5 56

f-block elements

Lanthanides and Actinides:

are wedged between groups 3B and 4B in the 6th and 7th period

mostly radioactivetrans-Uranium elements are all synthetic

Electron configuration: ns 0-2 (n-1) d 0-1 (n-2)f 1-14

Chapter-5 57

Glenn Seaborg (1912 – 1999)(UC Berkeley, 1944)

Development and arrangement of the Actinides

Discovery of transuranium elements

f-block elements

Chapter-5 58

Periodic Trends

Certain trends of each element determine its location in the periodic table:

Metallic/nonmetallic

Radius:

Atomic radius

Ionic radius

Ionization energy

Electron affinity

Electronegativity

Melting & boiling point

•Energy levels or shells: n

•Effective nuclear charge: Zeff

•Electron shielding

Chapter-5 59

Effective Nuclear Charge

Zeff is found this way:

Zeff = Z − S

S: usually close to the number of inner electrons

atomic number shielding

Electron Shielding:https://www.youtube.com/watch?v=V_LpZkDM360

Effective Nuclear Charge:https://www.youtube.com/watch?v=U0M6AHV52mk

Chapter-5 60

Sizes of Atoms and Ions

Half of the distance between two nuclei (in covalently bonded diatomic molecule)

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Chapter-5 61

Sizes of Atoms

Chapter-5 62

Period Trend:Atomic Radius

Chapter-5 63

Cations are smaller than their parent atoms

6.3

Treat electrons as pounds!

Lose electron → Form cation → Get smaller!

Chapter-5 64

Cations are smallerthan their parent atoms

Electrons are removed Zeff increased thus size gets smaller.

Chapter-5 65

Treat electrons as pounds!

Gain electron → Form anion → Get bigger!

Anions are bigger than their parent atom

Chapter-5 66

Anions are bigger than their parent atoms

Electrons are added Zeff decreased thus size gets bigger.

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Chapter-5 67

Within an isoelectronic group of ions, the one with the greatest nuclear charge will be the smallest.

•Note that they all have:•Different elements but have same number of electrons!

•Which one has the largest ionic radii?

•For example, look at the ions listed below.

All have 18 electrons

Isoelectronic Series

P3– S2– Cl– Ar K+ Ca2+

Chapter-5 68

Sizes of Atoms and Ions

Arrange the following in decreasing size: N, N2–, N3–

N3– > N2– > N

Arrange the following in decreasing size: Ca, Ca+, Ca2+

Ca > Ca+ > Ca2+

Arrange the size of these ions in the ascending order:

Sr+2 As3− Se2− Rb+ Br−

Sr+2 > Rb+ > Br− > Se2− > As3−

Chapter-5 69

A (g) + energy –> A+ (g) + e-

The process is endothermic!

Ionization Energy

Ionization Energy is energy required to remove an electron from the ground state of a gaseous atom or ion. First ionization energy: energy required to remove

first electron.

Second ionization energy: energy required to remove second electron, etc.

Smaller the IE easier to remove electron!Chapter-5 70

It requires more energy to remove each successive electron.

When all valence electrons have been removed, the ionization energy takes a quantum leap.

Ionization Energy

Chapter-5 71

Ionization energy increases

Chapter-5 72

Electron affinity is the energy release when an electron is added to a neutral atom in the gaseous state:

•For a fluorine atom, the first electron affinity is illustrated by:

•When F gains an electron, energy is released. The process is exothermic!

F(g) + e- → F-(g) EA = -328 kJ

F(1s22s22p5) + e- → F-(1s22s22p6)

Electron Affinity

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Chapter-5 73

Greater (-) value More stable atom A happy atom Higher electron affinity

Electron affinity increases

Chapter-5 74

Electronegativity

Electronegativity is a numerical value that shows the ability of an atom to attract electrons to itself in a chemical bond.

Fluorine, the most electronegative element, is arbitrarily assigned a value of 4.0. Values for other elements are calculated compared to Fluorine.

The most electronegative atoms are:

F O N


Atomic radius

Ato

mic

rad

ius

Electron affinity

Ele

ctro

n af

fini

ty

Ionization energy

Ioni

zatio

n en

ergy

Atomic Radius

Electron Affinity

Ionization Energy

Metallic/Nonmetallic Character

Electonegativity

Electronegativity

Ele

ctro

nega

tivity

Chapter-5 77

Summary of Periodic Trends

Atomic radius decreaseIonization energy increaseElectron affinity increaseElectronegativity increase

Chapter-5 78

Melting and Boiling Points

Instead of a generally increasing or decreasing trend, melting and boiling points reach two different peaks as d and p orbitals fill.

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