PERIODIC TABLE

PERIODIC
TABLE

1 CONTENT

Introduction Elements in period
Elements in group Ionic radius

Atomic radius Electronegativity
Ionisation energy

Application References

2 INTRODUCTION

• Five elements that I have chosen is sodium ,
magnesium, aluminium , flourine and chlorine

• The reason I choose sodium , magnesium and
aluminium is because they are located in the same
period which is period 3. So , I can compare and
classified them according to their atomic radius,
ionic radius, ionisation energy and electronegativity
across the period.

• The reason I choose flourine and chlorine is because
they are located in the same group which is group
17. So , I can compare and classified them according
to their atomic radius, ionic radius, ionisation energy
and electronegativity down the group.

3 ELEMENTS IN GROUP

 The groups in the periodic table are numbered from 1 to 18
 Elements in the same group have the same number of valence electrons

element Sodium Magnesium Aluminium Flourine Chlorine

Electronic 1s22s22p63s1 1s22s22p63s2 1s22s22p63s23p1 1s22s22p5 1s22s22p63s23p5

congfiguration 7

Valence 1 23 7 17
electron p-block
Halogens
Group 1 2 13 17
p-block
Block s-block s-block p-block Halogens

Classification Alkali metals Alkaline earth Transition

metal metals

 If the elements is in the block s and d ,
Group number = number of valence electron

 If the elements is in block p ,
Group number = Number of valence electron + 10

Element Group Outermost Explaination
orbital
sodium 1
magnesium 2 3s1 sodium has 1 valence electron and
aluminium 13 located in s-block. Therefore, sodium
flourine 17 located in group 1.
chlorine 17
3s2 Magnesium has 2 valence electrons and
located in s-blcok. Therefore, magnesium
located in group 2.

3s23p1 Aluminium has 3 valence electrons and
located at p-block. Therefore , aluminium
is located in group 13.

2s22p5 Flourine has 7 valence electrons and
located in p-block. Therefore, flourine
located in group 17.

3s23p5 Chlorine has 7 valence electrons and
located in p-block. Therefore, chlorine
located in group 17.

 Flourine and chlorine are in the same group ( group 17 ) because they have same
number of valence electron valence electron = 7

4 ELEMENT IN PERIOD

element sodium magnesium aluminium chlorine flourine

Electronic 1s22s22p63s1 1s22s22p63s2 1s22s22p63s23p1 1s22s22p5 1s22s22p63s23p5
3
congfiguration

Highest 3 33 2
principal
quantum
number

period 3 33 22

 The period in the periodic table are numbered 1 to 7
 Period number = number of shell = principal quantum number, n, of the

electrons in valence shell

element period explaination

sodium 3 The principal quantum number of the electrons
magnesium 3 in valence shell of sodium is 3 , n=3. Therefore ,
aluminium 3 sodium is located in period 3.
flourine 2
chlorine 3 The principal quantum number of the electrons
in valence shell of magnesium is 3 , n=3.
Therefore , sodium is located in period 3.

The pricipal quantum number of the electrons
in valence shell of aluminium is 3 , n=3.
Therefore , sodium is located in period 3.

The principal quantum number of the electrons
in valence shell of flourine is 2 , n=2. Therefore
, sodium is located in period 2.

The principal quantum number of the electrons
in valence shell of chlorine is 3 , n=3. Therefore
, sodium is located in period 3.

• Sodium , magnesium , aluminium and chlorine are located in the same period
because they have same principal quantum number of the elecctron in valence shell
n=3

5 ATOMIC RADIUS

Variation in atomic radii

• The atomic radius is taken as half of the distance between the

nuclei of two adjacent identical atoms

• The saiz/ radius of atom is difficult to be defined because the

electron cloud has no clear boundry.

• The atomic radius of an element across a period is determined by

a factor : Effective nuclear charge , Zeff

• The effective nuclear charge , Zeff is always the “ positive charge”

felt by an electron

Zeff = Z – S

• Where

Z = no of proton

S = no of inner or core electrons
• Electron moving around the nucleus do not experience the same

nucleus attraction
• Electron closer to the nucleus experience greater nuclues

attraction.

Screening effect

• Ability of other electrons , especially inner electron , to lessen the

nuclear attraction on an outher electron

element sodium magnesium aluminium flourine chlorine

Electronic 1s22s22p63s1 1s22s22p63s2 1s22s22p63s23p1 1s22s22p5 1s22s22p63s23p5

congfiguration

Proton 11 12 13 9 17

number

Inner electron 10 10 10 2 10

Zeff 11 – 1 = +1 12 – 10 = +2 13 – 10 = +3 9 – 2 = +7 17 – 10 = +7

Across period , from left to right , the atomic radius decrease because
o Proton number increase
o Inner electrons are same
o Outer electrons are pulled closer to nucleus
o Nucleus – electron attraction increases
o Atomic radius become smaller

magnesium Cl :1s22s22p63s2
Effective nuclear charge : 12– 10 = +2
12 p
12 n We can see the radii of Magnesium is
larger because the nucleus can only pull
the outer electrons closer with charge of
+2

Cl :1s22s22p63s23p5 17 p
Effective nuclear charge : 17– 10 = +7 18 n

We can see the radii of Chlorine is chlorine
smaller because the nucleus pulls the
outer electrons closer with charge of + 7

 Flourine is the smallest elements among this five elements because it is located in period 2 , it
has only 2 shells , while chlorine , sodium , magnesium and aluminium are in period 3 has 3
shells. Sheilding effect are more geater in chlorine, sodium, magnesium and aluminium because
it has more number of shells compared to flourine. So, attraction nucleus toward valence
electron are weaker , therefore they have larger size and atomic radius compare to Flourine.

 Chlorine , sodium , magnesium and aluminium located in period 3 , but across period 3 ,
proton number are increases, therefore effective nuclear charge Zeff of Chlorine are stronger
than sodium , magnesium and aluminium. So , the attraction between nucleus and outer
electrons are stronger. Thus, atomic radius of Chlorine are smaller than sodium , magnesium
and aluminium

flourine, chlorine , aluminium , magnesium , sodium

Increasing atomic radius

Down a group Across a period

Flourine < Chlorine Aluminium < Magnesium < Sodium

 Down a group , flourine has 2 shells • Across period , proton number of
while chlorine has 3 shells. aluminium is greater than
magnesium and sodium but the inner
 As number of shells increase, electron are same
chlorine has more inner electron
than flourine • The effective nuclear charge of
aluminium is greater than
 Inner electron sheild the outer magnesium and sodium
electron effectively and screening
effect increases in chlorine compared • Nucleus-electron attraction increases
to flourine in aluminium than magnesium and
sodium as the outer electrons are
 The attraction of the nucleus and puller closer to nucleus
outer electron become weaker in
chlorine compare to flourine • So , atomic radius of aluminium
becomes smaller compare to
 So , atomic radius of chlorine become magnesium and sodium
larger than atomic radius of flourine.

6 IONIC RADIUS

Cations Anions
( positive charge) ( negative charge)

• Always smaller than their natural atoms • Always larger than their natural atoms

• When electrons are removed from an atom , • It has more electron as it gains electron

repusion between atom decrease during its formation

• Since the number of proton remain , nuclear • When electron are added to an atom,
charge remain the same repulsion between electrons increase caused
it to spread out.

• Nucleus- electron attraction become stronger • Nucleus- electron attraction become waeker

• Remaining electron pulled closer towards the • rOeumtearinotrhbeitaslaem(xncephaeeanngrdiaogteneivv)een the nuclear charge
nucleus

• Electron cloud shrink • Electron cloud expend

11Na : 1s22s22p63s1

Na+ < Na

• 1 electron are removed from shell
• The number of shells reduced
• Zeff more significant
• Zeff become stronger at Na+
• Nucleus- electron attraction become stronger
• Saiz become smaller

12Mg : 1s22s22p63s2

Mg2+ < Mg

• 1 electron are removed from shell
• The number of shells reduced
• Zeff more significant
• Zeff become stronger at Mg2+
• Nucleus- electron attraction become stronger
• Saiz become smaller

13Al : 1s22s22p63s23p1

Al3+ < Al

• 3 electrons are removed from shell
• The number of shells reduced
• Zeff more significant
• Zeff become stronger at Al3+
• Nucleus- electron attraction become stronger
• Saiz become smaller

9F : 1s22s22p5
F < F-

• 1 electron are added to the outermost orbital
• Electron-electron repulsion stronger
• Zeff decrease at F-
• Nucleus- electron attraction become stronger
• Attraction nucleus and valence electron weaker
• Saiz become larger

17Cl : 1s22s22p63s23p5
Cl < Cl-

• 1 electron are added to the outermost orbital
• Electron-electron repulsion stronger
• Zeff decrease at Cl-
• Nucleus- electron attraction become stronger
• Attraction nucleus and valence electron weaker
• Saiz become larger

7 IONISATION ENERGY

First ionisation energy : the minimum energy required to remove one electron from the
outermost orbital of a neutral gaseous atom in a ground state

Acrosss a period Down a group

• Across a period , proton number • Number of shell increase , the sheilding
increase , therefore effective nuclear effect increase , atomic size also increase
charge ( Zeff ) increase. This causes the
saiz of the atom to decrease • Valence electrons are further away from
the nucleus and held less tightly by the
• Valence electron are closer to the nucleus
nucleus because attractions between
the nucleus and the valence electrons • Attraction between the nucleus and
are stronger. valence electrons are weaker

• More difficult to remove an electron • Easier to romove an electron from each
from the atom atom

• More energy is needed to remove the • So less energy is needed to remove the
outemost electron from an atom. first electron

• Thus , ionisation energy ( IE ) increase. • Thus , ionisation energy decrease

• In general , ionisation energy increase
from left to right

Across period Down a group

Sodium < Magnesium < Aluminium Flourine < Chlorine

Across a period , proton number of aluminium Down the group ,chlorine has more number of
is geater than sodium and magnesium , shell compare to flourine , so the sheilding
therefore effective nuclear charge ( Zeff ) effect increase and atomic size also increase in
increase in aluminium compare to sodium and chlorine compare to flourine
magnesium. This causes the saiz of the
aluminium to decrease

Valence electron of aluminium are closer to Valence electrons of chlorine are further away
the nucleus because attractions between the from the nucleus and held less tightly by the
nucleus and the valence electrons are nucleus comapre to flourine
stronger compared to magnesium and sodium

More difficult to remove an electron from Attraction between the nucleus and valence
aluminium compare to sodium and electrons are weaker in the chlorine atom
magnesium compare to flourine

More energy is needed to remove the Easier to romove an electron from chlorine

outermost electron from aluminium compare atom than flourine atom

to sodium and magnesium

Thus , ionisation energy ( IE ) increase in So less energy is needed to remove the first
aluminium than sodium and magnesium electron in the chlorine compare to flourine

In general , ionisation energy increase from Thus , ionisation energy is smaller in chlorine
left to right compare to flourine

element sodium magnesium aluminium chlorine flourine
1 2 13 17 17
group 3 3 3 3 2
496 738 578 1251 1681
period
1st IE
( KJ/mol )

Isoelectronic
• Spesies of atom and ion that have same electronic congfiguration

• Among these five elements that I have chosen, both Na+ and F- are isoelectronic.
Na+ and F- have same electronic congfiguration

• Na+ has larger effective nuclear charge compare to F-
• Na+ has more proton number than F-
• Attraction nucleus and valence electron of Na+ more stronger than F-
• So , Na+ pulled electron closer to nucleus compare to F-
• Therefore, size of Na+ is smaller than F-

Anomalous Cases of first ionisation energy in period 3
• The increase of ionisation energy with proton number is not uniform

Among these five elements that I have chosen , Magnesium ( group 2) and Aluminium (group 13)
are in anomalous cases.

• Between Mg ( group 2 ) and Al ( group 13 ), the first ionisation energy of Mg is greater than Al
• The electronic congfiguration of Mg and Al are as follows :

Mg (g) Mg+ (g) + e –
1s22s22p63s2 1s22s22p63s1
( fully filled 3p orbital )

Al (g) Al + (g) + e–
1s22s22p63s23p1 1s22s22p63s2
( partially filled 3p orbital )

The first ionisation energy of Mg > Al because

 The electron in 3p orbital of Al is at higher energy level than 3s electron in Mg.
 Attraction of nucleus towards the 3p electron is weaker
 Less energy is remove a single 3p electron in Al than to remove a paired 3s electron is Mg
 Therefore , ionisation energy (IE) of Al is lower than Mg
 Besides that , more energy is required to remove electron from a fully- filled 3s orbital in Mg

which is more stable
 So , Mg has higher first ionisation energy than Al

8 ELECTRONEGATIVITY

 Electronegativity is a chemical property that describes the tendency of an atom to

attract electrons of covalent bond towards itself
 Atoms with strong attraction of the nucleus and the outer electron have the high

electronegativity

Across a period Down a group

The proton number increase , nucleus charge Although the positive charge on the nucleus
become more positive, effective nuclear increases, this is more than offset by the
charge (Zeff) increase increase in the atomic radius and the
additional screening effect of the extra
electron shell

So , atomic radius decrease and atomic size Going down group, number of shell increase ,
become smaller the atomic size increase because the
screening effect increase

Attraction between nucleus and outer electron The attraction of the nucleus and outer

become stronger electron weaker

Hence, the atom has greater ralative tendency Hence , the atom has smaller relative tendency

to attract electrons in a bond to itself to attract electron to itself

Therefore , when across period , the Therefore, when going down group , the
electronegativity increase electronegativity decrease

sodium , magnesium , aluminium , chlorine , flourine

Electronegativity increase

Across period Down a group

Sodium < Magnesium < Aluminium

Across period , aluminium has more proton Going down the group , number of shell of
number than sodium and magnesium. Thus chlorine is more than number of shell of
nuclear charge become more positive and flourine. Atomic size of chlorine is bigger than
effective nuclear charge of aluminium is flourine because screening effect is higher in
higher than sodium and magnesium chlorine compare to flourine

So atomic radius of aluminium decrease and The attraction of the nucleus and outer
the size become smaller compare to sodium electron in chlorine is weaker compare to
and magnesium flourine

Attraction between nucleus and outer Hence , the chlorine has smaller relative
electron of aluminium are stronger than tendency to attract electron to itself compare
sodium and magnesium to flourine

Hence, aluminium has greater ralative Therefore, when going down group , the
tendency to attract electrons in a bond to electronegativity of chlorine is smaller than
itself compare to sodium and magnesium flourine

Therefore , across period , electronegativity of
aluminium is higher than sodium and
magnesium

9 APPLICATION

LOADING PAGE ….P HOW TO PLAY :

CLICK HERE TO PLAY • Choose the best answer
• Run to the correct zone
https://wordwall.net/play/22280/391/714
while avoid anemies
• Answer 20 questions all

of them
• After 3 wrong answers ,

game over. You can
repeat the game.
• Best score will be given
to the player that
answer the most
questions within the
time given

11 CONCLUSION

In a nutshell , across period 3 , atomic size of sodium , magnesium , aluminium and
chlorine will decrease. It is because across period proton number are increase and effective
nuclear charge also increase. Nucleus – electron attraction are increase and outer electrons
pulled closer to nucleus. Besides that, across period , ionisation energy also increase from
left to right. Electronegativity also increase across period.

Down group 17 , atomic size of flourine and chlorine will increase. It is because down a
group , number of shell increases. So , sheilding effect will increase and attraction between
nucleus and outer electron become weaker. Therefore , down a group , atomic size
increases. Moreover , down a group , ionisation energy will decrease because less energy
needed to remove the first electron. Down a group , electronegativity also decrease

Across period Atomic radius Ionisation energy Electronegativity
Down group decrease increase increase
increase decrease decrease

10 REFERENCES

Jennifer N. Hennigan and W. Tandy Grubbs . The Periodic Pyramid. Journal of
Chemical Education 2013, 90 (8) , 1003 - 1008.
https://doi.org/10.1021/ed3007567

The British Journal for the History of Science , Volume 19 , Issue 1 , March
1986 , pp. 3 -17
https://doi.org/10.1017/S000708740002272X

J.J. Lagowski. ( 1998 ). Periodic table. Retrived from
https://www.britannica.com/science/periodic-table

IUPAC | INTERNATIONAL UNION OF PURE AND APPLIED CHEMISTRY. (2016).
PERIODIC TABLE OF ELEMENTS. Retrived from https://iupac.org/what-we-
do/periodic-table-of-elements/

Pubchem . ( 2004 ) Periodic Table of Elements. Retrived from
https://pubchem.ncbi.nlm.nih.gov/periodic-table/

THANK YOU