PERIODIC TABLE OF ELEMENTSF4/CH04 CHAPTER 4: PERIODIC TABLE OF ELEMENTSA.INTRODUCTION-Elements are arranged systematically in the Periodic Table in the order of increasing proton number which enables:a) .b) .c) .-Below are the contributions of a few scientists to the development of the Periodic Table:-

SCIENTISTSDISCOVERIES

Antoinne Lavoiser(1743 - 1794)

He was the first chemist to classify substances including light and heat into metals and non-metals .. because compounds were also considered as elements.

Johann W Dobereiner(1780 - 1849)

In 1829 he divided the elements into groups of three with . (Deobereiners Triad) The atomic mass of the middle element was approximately the average atomic mass of the other two elements in each triad. Led chemists to realise that there was a relationship between the chemical properties and the atomic mass of each elements.

John Newlands(1837-1898)

Lothar Meyer(1830 - 1895)

Dmitri Mendeleev(1834 - 1907)

Hendry J.G Moseley(1887 - 1915)

So below is an overview of the modern Periodic Table of elements:-

-Elements in the periodic table of elements are arranged in the order of increasing .-Two main components of the Periodic Table of Elements are :-1. ..2. ..-Position of elements are determined by its and .-Valence electrons : -Electron shells : ELEMENTSPROTON NUMBERELECTRON ARRANGEMENTNUMBER OF VALENCE ELECTRONSGROUPNUMBER OF SHELLPERIOD

H

He

Li

B

N

F

Ne

Na

B.GROUP 18 (NOBLE GASES)-Group 18 is known as Noble gases and they are very inert.-It is consists of .. .-They exist as .. at room condition because Noble gases .... which is a for helium and .. for other elements of other noble gases.-So the element in G18 does not have to .. .

PHYSICAL PROPERTIES OF GROUP 18 ELEMENTS.

ElementsExplanation

1. The atomic size ..as we go down the group because of the ..... .2. Melting point and boiling point is very low .. are attracted by .. . Therefore less heat energy is needed to overcome these forces. However MP and BP . as we go down the group since . so will the Van der Waal forces.

3. Density is low and increases gradually because mass increases going down the group.

4. All noble gases are in water and . in all conditions

CHEMICAL PROPERTIES OF GROUP 18-There are NO chemical property for group 18 because: -Since all of its elements have .. there would be USES OF GROUP 18 ELEMENTSNoble GasesUses

Helium

Neon

Argon

Krypton

Xenon

Radon

C.GROUP 1 (ALKALI METALS)-Group 1 elements are known as alkali metals. The ElementsSymbol Proton no.Electron configurationNo. of shells

Lithium

Sodium

Potassium

Rubidium372.8.18.8.1

Caesium552.8.18.18.8.1

Francium872.8.18.32.18.8.1

PHYSICAL PROPERTIES OF GROUP 1a) ..b) ..c) ..

ElementsExplanation

LiNaKRbCsFr1. The atomic size ..as we go down the group because of the .... .2. Melting point and boiling point .....................................................................................................................................................................

3. Density is low and increases gradually because mass increases going down the group.

CHEMICAL PROPERTIES OF GROUP 1i. Li Li+ + e-Na Na+ + e-

K K+ + e-

ii. All elements in Group 1 have because in Group 1 . by . to form .iii. Reactivity of alkali metals .. because .(ELECTROPOSITIVITY - ..)Eg:Lithium is less reactive than sodium. Explain why.Going down Group 1, the number of .., the .................. and the single electron in the gets . from the nucleus. The ... gets and the valence electron is .. . Therefore .. . CHEMICAL REACTIONS OF GROUP 1i)With water

ElementsObservationsReactions

Lithium,Li

Sodium, Na

Potassium,K

General equation for the reaction is :.. (where X is Li, Na, K, Cs, Rb, Fr)

ii)With chlorine gas, Cl2ElementsObservationsReactions

Lithium,Li

Sodium, Na

Potassium,K

CONCLUSION:

iii)With oxygen gas, O2ElementsObservationsReactions

Lithium,Li

Sodium, Na

Potassium,K

CONCLUSION:

GROUP 17 (HALOGENS)-Group 17 elements are known as HALOGENS.ElementsSymbol Proton no.Electron configurationNo. of shells

FluorineF92.72

ChlorineCl172.8.73

BromineBr352.8.18.74

IodineI532.8.18.18.75

AstatineAt552.8.18.32.18.76

PHYSICAL PROPERTIES OF G17a) The physical state change from gaseous (F2/ Cl2) to liquid (Br2) and then to solid (I2)b) ATOMIC SIZE increase going down the groupc) Low densities but DENSITY INCREASES going down the group.d) MP and BP are low initially. But they INCREASE going down the group.ElementsExplanation

1. ATOMIC RADIUS Atomic radius increases as we go down the group

2. DENSITY Low density compared to other elements but density increases as we go down the group Atomic size increases therefore number of occupied electron shells would also increase. Mass would increase thus DENSITY INCREASES.

3. MP & BP Increase as we go down the group Forces of attraction of the Van der Waals forces become stronger as size of atom increase More heat energy is needed to overcome the forces of attraction.

4. ELECTRONEGATIVITY All halogens have high electronegativity. Electronegativity decrease going down the group due to the increase in atomic size Forces of attraction from the nucleus towards valence electron is weak Reactivity decreases

CHEMICAL REACTIONS OF G17I. Reaction with water, H2OSolubility (reactivity) decreases going down the groupII. Reaction with iron, Fe-Reacts readily for fluorine and chlorine but slowly with Bromine and iodine-All halogens react to form iron (III) chloride-Example:- Chlorine and iron -For chlorine and bromine, sodium hydroxide solution is used to absorb excess gas.

III. Reaction with sodium hydroxide, NaOH-Apparatus set-up is the same as reaction with water-Chlorine reacts to form sodium chlorate (I), sodium chloride and water -Example:- Bromine and NaOH.

PERIOD 3ElementsNaMgAlSiPSClAr

Proton no1112131415161718

Electron arrangement

Nucleus charge+11+14+17+18

Radius0.1560.1360.1250.1170.1100.1040.0090.001

PHYSICAL PROPERTIES

Atomic radius

Atomic radius decrease going across the period. (left to right). Why? All the elements I period 3 have the same number of occupied electron shells but the proton number is increasing for each successive elements The increase in proton number causes the positive charge in the nucleus to INCREASE so it would attract electron with a much stronger force. So the nucleus attraction on the valence electron increase and the atomic radius

Electronegativity

Electronegativity increases going across the period (left to right). Why? Electronegativity increase going across the period because of the increase in the nuclear charge// proton number from left to right (increase by one) It causes an INCREASE in the strength to ATTRACT the valence electron so electronegativity would INCREASE

Physical State Physical state changes from solid to gas going across the period

Metallic properties Metallic properties decreases going across the period. Changes from metal semi-metal non-metal

NaMgAlSiPSClAr

Good electrical conductor Cant conduct electricity

CHEMICAL PROPERTIESElementsNaMgAlSiPSClAr

Proton no1112131415161718

Formation of oxides

Metals form basic oxides when reacted with oxygen. So metal oxides would show basic or alkaline properties such as turning the litmus paper from red to blue. Non-metals form acidic oxides when reacted with oxygen. Non-metal-oxides would show acidic properties Aluminiun is different. It would form amphoteric oxides and show bopth acidic and basic propertiers

Metal oxides + water alkali ; ...Non-metal oxides + water acid;

So oxides of period 3 changes from :Basic oxides amphoteric oxides acidic oxides

F.TRANSITION ELEMENTSPhysical properties:-1. .2. .3. .4. .5. .

SPECIAL PROPERTIES

1.Variable Oxidation Numbers (Charge on ions) Elements like calcium and magnesium .... can only form ONE oxidation number. Oxidation number - . Transition element however can form ... Eg: ...................

2.Formation of coloured compounds Compounds of transition element can form . Eg:

3.Catalytic properties Catalyst - Eg :.......... Mainly used in industrial process.

4.Formation of complex ions Transition Elements can form COMPLEX IONS Complex Ions central metal ion bonded to other atoms or groups of atoms. They are brightly coloured.

USES OF TRANSITION ELEMENTSRefer to your textbooks/ reference books and do your own notes!!

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