periodic table of elements - · pdf filemohd faisol mansor/chemistry form 4/chapter 4 58...

mohd faisol mansor/chemistry form 4/chapter 4

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CHAPTER 4 PERIODIC TABLE OF ELEMENTS


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PERIODIC TABLE


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Historical Development of Periodic Table

Johann Dobereiner

(1780 – 1849)

divided element

according their

similar chemical

properties

Antoine Lavoiser

(1743 – 1794)

first scientist classify

substances.

John Newlands

(1837 – 1898)

arranged element

in order of

increasing atomic

mass

Lothar Meyer

(1830 – 1895)

showing that the

properties of the elements

formed a periodic

pattern against their

atomic masses.

Dmitri Mendeleev

(1834 – 1907)

arranged the elements in

order of increasing atomic

mass and

grouped them

according to similar

chemical properties.

Henry J.G. Moseley

(1887 – 1915)

Studied the X-ray

spectrum of elements.

He rearranged the

elements in order of

increasing proton number.

Concluded that the

proton number should

be the basis for the

periodic change of

chemical properties

instead of the atomic

mass.

Leading to the modern

Periodic Table.


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Arrangement of Element in the Periodic Table

Element in the

Periodic Table are

arranged in an

increasing order of

proton number

ranging 1 to 118.

Element with

similar chemical

properties are

placed in the same

vertical column

18 vertical column

called a group

7 horizontal rows

called a period

GROUP

The number of

valence electron in

an atom decides the

position of the group

of an element.

GROUP

Valence electron 1

and 2

GROUP

Valence electron 3

until 8

PERIOD

Equal to the number

of shell occupied

with electrons in its

atom

Example:

An atom of element X has a proton

number of 15. In which group and period

we can find element X in Periodic Table.


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1. Element D has a proton number 19. Where is element D located in Periodic

Table?

2. An atom of element E has 10 neutrons. The nucleon number of element E is 19.

In which group and period of element E located in the Periodic Table?

3. An atom of element G has 3 shell occupied with electrons. It is placed in

Group 17 of the Periodic Table. What is the electron arrangement of atom G?

4. An atom Y is located in Group 18 and period 2 of the periodic Table. What is

the electron arrangement and proton number of atom Y?

5. Element R has a proton number of 11. Its atom has 6 neutrons. In which group

and period can you find element R in the Periodic Table?

Atom, Molecule & Ion

Exercise


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The advantage of grouping elements in the Periodic Table

1. Helps us to study the element systematically especially their

physical and chemical properties.

2. Element with a same number valence electron is place in the

same group because they have the same chemical properties.

3. It could be used to predict undiscovered properties.

4. To relate the characteristic of an element with atomic structure


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Physical Properties of Group 18

GROUP 18

consist of helium,

neon, argon,

krypton, xenon

and radon

GROUP 18

Known as

NOBLE GAS

Exist as

monoatomic gas.

GROUP 18

NOBLE GAS

COLOUR SOLUBILITY

ELECTRIC

CONDUCTIVITY

MELTING &

BOILING POINT

DENSITY


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The inert properties of G18

All noble gas are inert which means unreactive.

Noble gas are inert because the outermost occupied shell are full.

This electron arrangements are very stable.

Helium have 2 valence electron, this electron arrangement is called

duplet electron arrangement whereas other noble gas have eight

valence electron which called octet electron arrangement.

p/s: All other element try to achieve noble gas electron arrangement to

become stable.

The Physical Properties of G18

The physical properties vary down the group.

physical properties vary down the group are related to atomic size.

Melting and boiling point of an element increase when going

down the group because the atomic sizes increase, the forces

attraction (Van der Waals forces) becomes stronger. Thus more

heat energy is required to overcome the forces.

The strength of Van der Waals forces propotional to the size of

particle


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Uses of Noble Gas Elements

Fill light bulb laser for repair retina,

photographic flash lamps

fill airships and weather

balloons

treatment cancer

advertising light and

television tubes

Car bulb, use in bubble chamber

[ State the element of group 18 ]


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1. Table below shows the electron arrangements of atoms of elements P, Q,

and R.

Element Electron Arrangement

P 2.8

Q 2.8.18.8

R 2.8.18.32.18.8

a) Arrange the element in ascending order of boiling points. Give reasons for

your answer.

b) Elements P, Q, and R are chemically unreactive. Why?

2) What is the meaning of

a) Duplet electron arrangement

b) Octet electron arrangement

Exercise


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Physical Properties of Group 1

GROUP 1

Known as Alkali

Metals.

Have valence

electron of 1.

Consist of elements

such as lithium,

sodium, potassium,

rubidium, caesium

and francium.

GROUP 1

ALKALI

METALS

HARDNESS APPEARANCE

ELECTRIC

CONDUCTIVITY

MELTING

POINT

DENSITY


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A melting point of a metal indicates the strength of its metallic bonding in its

structure.

Generally, the strength of metallic bonding is directly proportional to the number

of valence electron per atom divided by the radius of a metal.

A metallic bond can be defined as the electrostatic force between the

positively charged metallic ions and the ‘sea’ of electrons.

Electropositivity is the measurement of an atom to release an electron and form

positive ion

When going down the group, what happen to the electropositivity of the

element? Why?

Element Atomic Size

Melting /

Boiling

point

Density Hardness

Lithium

Sodium

Potassium

Rubidium

Caesium

Francium


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Chemical Properties of Group 1 Elements

Exercise :

1. Why does Group 1 element have similar chemical properties?

2. Why is paraffin oil used to store metals such as sodium and potassium?

3. Element in Group 1 has similar chemical properties but differ in reactivity.

Why?

React vigorously with water to produce alkaline metal hydroxide solution

and hydrogen gas, H2.

2Li (s) + 2H2O 2LiOH (aq) + H2 (g)

Burn in oxygen gas rapidly to produce solid metal oxide

4Li (s) + O2 (g) 2 Li2O (s)

Solid metal oxide dissolve in water to form alkaline metal hydroxide

Li2O (s) + H2O 2LiOH (aq)

Alkaline metal burn in chlorine gas, Cl2 to form white solid metal chloride

2Na (s) + Cl2 2NaCl (aq)


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To investigate the chemical properties of Lithium, Sodium & Potassium

[ Discussion ]

1. Why are the experiments involving sodium and potassium demonstrated by

your teacher and not carried out by the students?

2. Write the chemical equations for the reactions of lithium, sodium and

potassium with

a) Water, H2O

Lithium :

Sodium :

Potassium :

b) Oxygen gas, O2

Lithium :

Sodium :

Potassium :

[ Draw the diagram ]

1) The reaction of alkali metals with water

2) The reaction of alkali metals with O2 gas

[ Draw the diagram ]


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3. Write the chemical equations for the reactions between the products from

the combustion of each alkali metal with water.

Lithium :

Sodium :

Potassium :

1. A student performs two experiments to study the reaction of alkali metal with

water.

Experiment Metal used Observation

1 Sodium Sodium moves rapidly and randomly on the

water surface and emits ‘hiss’ sounds.

2 Lithium Lithium moves slowly on the water surface.

a) Write the chemical equation for the reaction between sodium and lithium

with water.

Lithium :

Sodium :

b) Between reactions of Experiment 1 and 2, which is more vigorous? Explain

your answer from the point of electron arrangement.

c) Explain why sodium and lithium show similar chemical properties?

d) Calculate the volume of hydrogen gas produced if 2.3 g of sodium is used.

[RAM: Na, 23 ; molar volume: 24 dm3 mol-1]

Exercise


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GROUP 17

consist of fluorine,

chlorine, bromine,

iodine and

astatine.

GROUP 17

Known as

HALOGENS.

Have valence

electron of 7.

GROUP 17

Elements are

poisonous.

Exist as diatomic

molecules.

Element Symbol of

Atom

Symbol of

Molecule

Physical

state at

room

condition

Colour

Fluorine

Chlorine

Bromine

Iodine

Astatine

Physical State

HALOGENS

Melting & Boiling

Point Electric

Conductivity

Density

Smell


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Electronegativity is an ability of atom to receive an electron to become

negative charged ions.

All halogen have seven valence electron. Their atoms always gain one electron

to form an ion with a charge of –1, in order to achieve stable octet electron

arrangement.

Chemical Properties of Group 17 Elements

Element Atomic

Size

Melting /

Boiling

point

Density Electronegativity

Fluorine

Chlorine

Bromine

Iodine

Astatine

Halogen react with water to produce two acids

Cl2 + H2O HCl + HOCl

Halogen react with metal to produce metal halides

2Fe (s) + 3Cl2 (g) FeCl3 (s)

Halogen react with sodium hydroxide solution to form sodium

halide and sodium halate (I) and water

I2(s) + 2NaOH (aq) NaI (aq) + NaOI (aq) + H2O (l)


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To Investigate the Chemical Properties of Halogens

[Draw the Apparatus]

SECTION A : Reaction with Water

1) Chlorine

2) Bromine 3) Iodine

SECTION B : Reaction with Iron

1) Chlorine


SECTION C : Reaction with Sodium Hydroxide

1) Chlorine



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[Discussion]

1. Name the products formed when chlorine, bromine, and iodine

react with water.

Chlorine :

Bromine :

Iodine :

2. Write the chemical equations for the reaction of chlorine,

bromine and iodine with water.

Chlorine :

Bromine :

Iodine :

3. What is the function of soda lime in SECTION B?


react with iron.

Chlorine :

Bromine :

Iodine :

5. Write the chemical equation for the reaction of chlorine,

bromine, and iodine with iron.

Chlorine :

Bromine :

Iodine :


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react with sodium hydroxide solution.

Chlorine :

Bromine :

Iodine :

5. Write the chemical equation for the reaction of chlorine,

bromine, and iodine with sodium hydroxide solution.

Chlorine :

Bromine :

Iodine :

6. Describe the changes in reactivity of Group 17 elements when

going down the group. Explain your answer.


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1. Table below shows several halogen elements with their proton numbers.

Halogen Proton Number

X 9

Y 17

Z 35

a) State the group that the halogen elements belong to in the Periodic Table.

b) i) Write the electron arrangement of elements X and Y.

ii) From your answers in (b)(i), deduce the period of elements X and Y.

c) Draw the electron arrangement of element Y.

d) State the changes of properties of halogens down the group from X to Z in

terms of:

i) Atomic radius

ii) Electronegativity

iii) Melting point and boiling point

Exercise


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e) i) Iron glow brightly when reacting with element Y. Write the chemical

reaction to represent this reaction.

ii) Predict the observation for the reaction between iron and element Z.

iii) Between Y and Z, which is more reactive? Explain why.

f) i) Determine the elements X, Y and Z.

ii) State the colour for each elements X, Y, and Z.

iii) Why the physical state of halogen differ when down the group?


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Comparison & Similarities between Group 1 and Group 17

Properties Group Down the Group

Atomic

Size

1

17

Melting &

Boiling

Point

1

17

Density 1

17

Reactivity 1

17


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Elements in a Period 3

Element Sodium Magnesium Aluminium Silicon Phosphorus Sulphur Chlorine Argon

Symbol

Proton Number

Electron

Arrangement

Metal Properties

Physical State

[RC]

Atomic Radius

Electronegativity

Property of the

oxide

Note: the atomic radius ______________ and electro negativity ______________

due to the increasing nuclei attraction on the valence electrons.

(nuclei attraction force increase with the increase of proton number)

The proton number ____________ by one unit.

All atom of the element have __________ shells occupied by electron.

The number of valence electron ____________ from 1 to 8.

All element exist as __________ except chlorine and argon.

The atomic radius of element ________________.

The electronegativity of element ______________.

The oxides of element in Period 3 change from basic to acidic properties,

therefore the metallic properties decrease across the period. On the other

hand non-metallic properties of the elements increase.


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Transition Elements

Transition elements are elements from Group 3 to Group 12

All the elements are metals, usually solids with shiny surfaces, ductile,

malleable and have tensile strength.

Have high melting and boiling point as well as high density.

Good conductors of heat and electricity.

Three special characteristics of transition element

Show different oxidation number in their compound.

Form coloured ions or compound.

Act as catalysts.

periodic table of elements - · pdf filemohd faisol mansor/chemistry form 4/chapter 4 58...

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