Periodic table
Alchemy.
Origin of elements.
Discovery of the elements.
Overview of the periodic table.
Electron configuration.
Madelung's rule.
The symmetry in the periodic table.
Valence.
Periodic table.
Metalloid.
Metals.
Non metals.
Alkaline earth metals.
Transition metals.
Boron group.
Carbon group.
Nitrogen group.
Oxygen group.
Halogens.
Noble gases.
Lanthanides.
Actinides.
Synthetic elements.
Alchemy.
The science of chemistry, has an interesting origin.
Early philosophers, tried to convert, base elements into Silver or Gold.
The motivation was economic.
Silver and Gold, had an high economic value.
A lot of scientific research, went into finding chemical reactions,
to convert elements like mercury, into silver and gold.
These early scientists, were called alchemists.
We now know, that one element, cannot be converted to another,
in a chemical reaction.
Each element is unique, and has a unique atomic number.
Alchemists, however played a role, in the systematic investigation,
of the properties of elements.
They laid the foundation of modern chemistry.
Grouping of elements, according to the properties,
was one of the efforts, of early scientists.
The modern periodic table, is built upon these early efforts.
Origin of elements.
The sun comprises mostly of 2 elements, Hydrogen and Helium.
All the stars, are also comprised of mostly, Hydrogen and Helium.
In fact, 99% of the universe, is comprised of only Hydrogen and Helium.
They are primordial elements.
Stars have a life cycle.
An explosion of a dying star, is called as a supernova.
During this explosion, massive nuclear reactions takes place.
New heavier elements like carbon, iron, copper etc are created.
These are expelled into the universe.
The Earth and the other planets, comprise of the elements formed in dying stars.
So, the Earth was born with all the naturally occurring elements.
The periodic table, tries to group these elements, according to their properties.
Discovery of the elements.
The earliest element, we discovered was Copper.
Later, we discovered Iron.
Over time, scientist were able to identify, most of the commonly occurring elements.
They knew that each element was unique.
They also knew that some elements, had similar properties.
For example, sodium and potassium exhibited, similar properties.
Many scientists tried to group the elements, based on similar properties.
The foundation, for the modern periodic table, was laid by Mendeleev.
The periodic table, that we use today, is a refined version of Mendeleev’s periodic table.
The basic principle, that Mendeleev used was, that when elements were ordered,
according to atomic number,
the properties periodically, repeated at some interval.
Based on this Mendeleev grouped elements, with similar properties.
Mendeleev’s periodic table, was published in 1869.
He even predicted, the existence of some missing elements.
Scientists discovered this missing elements, much later.
We use a refined version of this table, even today.
Our understanding of atomic structure, has significantly improved since then.
We now know much more about, the orbital properties of electrons.
We know that, the electrons in the outer most valency shell,
define the chemical properties, of the element.
Today, we can understand the periodic table,
from a perspective of the orbital properties, of electrons.
The amazing fact is, even from this modern perspective,
the beauty of the symmetry, of the periodic table, is retained.
Overview of the periodic table.
The periodic table, like it’s name implies, is a table of rows and columns.
It has 18 columns.
It has 7 rows.
There are many cells in the table.
One cell corresponds to a particular row, and a particular column.
It has 2 additional rows, at the bottom.
Every element has a unique atomic number.
The atomic number, is the number of protons, in the atom of the element.
It is also the number of electrons, in the element’s atom.
Every element occupies one unique cell, in the periodic table.
The elements are organised, according to increasing atomic number.
There are 118 known elements.
Their atomic number ranges from 1 to 118.
Each of these 118 elements, has a unique cell, in the periodic table.
As we move from left to right, the atomic number increases.
The lower rows, have a higher series of atomic numbers.
Each row, is called a period.
So, our periodic table has 7 periods, 1 to 7.
We should also remember, that there are two additional rows, in the bottom.
Each column corresponds, to a group.
Each group is like a family.
The elements in each group, have similar properties.
There are 18 groups, in the periodic table.
The first group, is called the alkaline metals.
The second group, is called the alkaline earth metals.
Groups 3 to 12 are clubbed together, and are called transition metals.
Group 13 is called the boron group.
Group 14 is called the carbon group.
Group 15 is called the nitrogen group.
Group 16 is called the oxygen group.
Group 17 is called the halogens group.
Group 18 is called the noble gases.
Hydrogen is a unique element.
For practical purposes, it is not considered, as part of any group.
Elements in group 1, like sodium and potassium are highly chemically reactive.
They easily form compounds, with many other elements.
Elements in group 18, like helium, neon, argon and krypton, are chemically inert.
They are called noble elements.
They do not combine, with other elements.
The first period, has Hydrogen with atomic number 1, in the 1st group,
and Helium, with atomic number 2, in the 18th group.
The second period has Lithium, with atomic number 3 in the 1st group,
and Neon, with atomic number 10, in the 18th group.
The third period has Sodium, with atomic number 11, in the 1st group,
and Argon, with atomic number 18, in the 18th group.
The fourth period has Potassium, with atomic number 19, in the 1st group,
and Krypton, with atomic number 36, in the 18th group.
The fifth period has Rubidium, with atomic number 37, in the 1st group,
and Xenon, with atomic number 54, in the 18th group.
The sixth period has Caesium, with the atomic number 55, in the 1st group,
and Radon, with atomic number 88, in the 18th group.
The seventh period has Francium, with the atomic number 87, in the 1st group,
and Ununoctium, with atomic number 118, in the 18th group.
There are two separate rows, at the bottom.
The 1st row, starts with Lanthanum, with atomic number 57,
and ends with ytterbium, with atomic number 70.
This row is called as the Lanthanide.
The 2nd row, starts with Actinium, with atomic number 89,
and ends with Nobelium, with atomic number 102.
This row is called as the Actinide.
If we fill in all the other elements, according to their atomic number,
in the table, we have the modern periodic table.
This covers all the 118 elements, that are known.
Electron Configuration.
An atom has protons, neutrons, and electrons.
The number of protons, in the atom defines the atomic number.
The number of electrons, in an atom is equal to,
the number of protons, or atomic number.
The electron orbits the nucleus.
There is a pattern, in which the electrons, orbit the nucleus.
The orbit comprises of concentric shells.
The main shells are named as ‘K’ shell, ‘L’ shell, ‘M’ shell, ’N’ shell, etc.
The ‘K’ shell is the inner most shell.
The ‘L’ shell, the ‘M’ shell, and the ’N’ shell, are progressively outer shells.
The inner shells, are closer to the nucleus.
The outer shells, are further and further away, from the nucleus.
We can also give numbers, to the shells.
The 1st shell, is the ‘K’ shell.
The 2nd shell, is the ‘L’ shell.
The 3rd shell, is the ‘M’ shell.
The 4th shell, is the ’N’ shell.
These numbers are called as the principal quantum numbers.
The shells, have sub shells.
The 1st sub shell, is called as the ’s’ sub shell.
The 2nd sub shell, is called as the ‘p’ sub shell.
The 3rd sub shell, is called as the ‘d’ sub shell.
The 4th sub shell, is called as the ‘f’ sub shell.
The ’s’ sub shell, is the inner most sub shell.
The ‘p’ sub shell, the ‘d’ sub shell, the ‘f’ sub shell,
are progressively outer sub shells.
We can visualise the orbit of electrons, as a number of concentric circles,
with shells and sub shells.
The electrons, that orbit the atom, group themselves into sub shells.
The sub shells, group themselves, into main shells.
Each sub shell, can have a maximum number of electrons.
Each main shell, can have a maximum number of electrons.
The ’s’ sub shell, can hold a maximum of 2 electrons.
The ‘p’ sub shell, can hold a maximum of 6 electrons.
The ‘d’ sub shell, can hold a maximum of 10 electrons.
The ‘f’ sub shell, can hold a maximum of 14 electrons.
The number of electrons, that the main ‘K’, ‘L’, ‘M’, ’N’, shells,
can hold, is given by the formula, 2 into, ’n’, squared.
’n’, is the principal quantum number.
In the ‘K’ shell, ’n’, = 1.
The maximum number of electrons, that the ‘K’, shell can hold = 2 electrons.
In the ‘L’ shell, ’n’ = 2.
The maximum number of electrons, that the ‘L’ shell can hold = 8 electrons.
In the ‘M’ shell, n = 3.
The maximum number of electrons, that the ‘M’ shell can hold = 18 electrons.
In the ’N’ shell, n = 4.
The maximum number of electrons, that the ’N’ shell can hold = 32 electrons.
We can now calculate, what sub shells, will be present in each main shell.
The 1st ‘K’ shell, can hold maximum of 2 electrons.
The ’s’ sub shell, can hold maximum of 2 electrons.
So, the 1st or the ‘K’ shell, can hold only 1 ’s’ sub shell.
Hydrogen, has an atomic number, of 1.
It has 1 electron, in the ’s’ sub shell, of the 1st main shell.
This is written as, 1 ’s’.
Helium, has an atomic number, of 2.
It has 2 electrons, in the ’s’ sub shell, of the 1st main shell.
This is written as, 1 ’s’, superscript 2.
For convenience, we will call it as 1 ’s’ 2.
In this module, we will follow the convention, of not mentioning super script.
The 2nd ‘L’ shell can hold a maximum of 8 electrons.
It can hold 1 ’s’ sub shell, with 2 electrons,
and 1 ‘p’ sub shell, with 6 electrons,
For a total of 2 + 6 = 8 electrons.
Carbon, has a atomic number of 6.
It has 2 electrons, in the ’s’ sub shell, of the 1st main ‘K’ shell.
It has 2 electrons, in the ’s’ sub shell, of the 2nd main ‘L’ shell.
It has 2 electrons, in the ‘p’ sub shell, of the 2nd main ‘L’ shell.
This makes a total of 2, + 2, + 2, = 6, electrons.
The electron configuration of carbon, is written as,
1 ’s’ 2, 2 ’s’ 2, 2 ‘p’ 2.
2 ‘p’ 2, means second main shell, ‘p’ sub shell, with 2 electrons.
Note. According to our convention, we do not mention super script.
So, 1 ’s’ 2, 2 ’s’ 2, 2 ‘p’ 2,
has 2 ,+ 2, + 2, = 6, electrons.
Neon, has a atomic number of 10.
It’s electron configuration,
is, 1 ’s’ 2, 2 ’s’ 2, 2 ‘p’ 6.
You will notice, that the ‘p’ sub shell, is full, with 6 electrons.
Neon, is an inert or noble gas.
It does not react, with other elements.
We will later come to know, how this periodicity repeats.
The 3rd ’M’ shell can hold a maximum of 18 electrons.
It can hold 2 electrons, in the 3 ’s’ sub shell.
It can hold 6 electrons, in the 3 ‘p’ sub shell.
It can hold 10 electrons, in the 3 ‘d’ sub shell.
Totally it can hold 2, + 6 ,+ 10, = 18, electrons.
The 4th ’N’ shell, can hold a maximum of 32 electrons.
It can hold 2 electrons, in the 4 ’s’ sub shell.
It can hold 6 electrons, in the 4 ‘p’ sub shell.
It can hold 10 electrons, in the 4 ‘d’ sub shell.
It can hold 14 electrons, in the 4 ‘f’ sub shell.
Totally it can hold 2, + 6, + 10, + 14, = 32, electrons.
Madelung's rule.
If we know, the atomic number of the element,
We can configure the electron shells.
In general, the lower shells will get filled up first.
The higher shells, will get filled up later.
But, there is an exception to this.
The true order of filling up, will be according to Madelung's rule,
or the diagonal rule.
The following is the sequence, for filling up the orbitals,
according to the Madelung's rule.
1 ’s’, 2 ’s’, 2 ‘p’, 3 ’s’, 3 ‘p’, 4 ’s’, 3 ‘d’, 4 ‘p’, 5 ’s’ and so on.
We will note and remember, that the orbit 4 ’s’, is filled before the orbit 3 ‘d’.
This rule, is based on quantum behaviour, of electrons.
We will not discuss the theory, in this module, but will follow the diagonal rule.
The symmetry in the periodic table.
The periodic table has 7 rows, and 18 columns.
It has 2 separate rows at the bottom.
We will visualise the periodic table, in terms of electron configuration.
This method, reveals the beautiful symmetry of the periodic table.
We will first deal with the 1st row.
The 1st row in the periodic table, has only 2 elements.
Hydrogen and Helium.
Hydrogen is a primordial element, with the atomic number 1.
It does not fit into any group.
Helium, with atomic number 2, has 2 electrons in the ’s’ sub shell.
It belongs to group 18.
For our symmetric model, we will leave out row 1, with Hydrogen and Helium.
We can now visualise, the periodic table, with 6 rows, and 18 columns.
There are 2 separate rows at the bottom.
We can visualise, 4 distinct blocks, in the main periodic table.
The 1st block, is the ’s’, block.
It has two columns, which is group 1 and group 2.
This block corresponds to the ’s’ sub shell, we discussed.
The ’s’ sub shell, we know, has a capacity of 2 electrons.
So, the ’s’ block has two groups.
The second block, is the ‘d’ block.
It has 10 columns or groups.
Group 3, to 12, belongs to ‘d’ block.
This corresponds to the ‘d’ sub shell, we discussed.
The ‘d’ sub shell, can hold 10 electrons.
The ‘d’ block has 10 groups, to represent this.
The 3rd block, is the ‘p’ block.
It has 6 columns or groups.
Group 13, to 18, belongs to ‘p’ block.
Now, we have a nicely partitioned symmetric periodic table.
It has an ’s’ block, ‘d’ block, and a ‘p’ block.
It has 6 rows, which creates a unique cell for each element.
The lower rows, has the heavier elements, with higher atomic numbers.
Lighter elements do not have a ‘d’ block,
because the atomic number is very low.
So, the cells in row 1 and row 2, of the ‘d’ block, is blank.
There are no elements corresponding to these cells.
To fill in the symmetric periodic table, we just need to know,
the atomic number of the element.
If we know the atomic number, we know the number of electrons.
If we know the number of electrons, we know the electron orbit configuration,
of the shells and the sub shells.
The ’s’ block, the ‘d’ block and the ‘p’ block,
represent the number of electrons, in the outer most shell,
in the main periodic table .
Valency.
The outer most shell, is also called as the valency shell of the element.
The valency shell of the element, determines the chemical behaviour,
of the element.
Elements tend to combine, in a manner, so that there are 8 electrons,
in the outer most shell.
Elements with 8 electrons, in the outer most shell, are inert.
That is, they rarely combine, with other elements.
They are called as noble elements, or noble gases.
Neon, Argon, Krypton, are examples of noble gases.
They have 8 electrons, in the outer most shell.
The typical configuration, of these 8 electrons, will be ’s’ 2, ‘p’ 6.
That is, they will have 2 electrons, in the ’s’ shell, and 6 electrons in the ‘p’ shell.
This adds up to an octet of 8 electrons, in the valency shell.
These elements, have no affinity or 0 valency.
Elements with one electron, in the outer most ’s’, shell, are very reactive.
They are very eager, to share, one electron with another element.
They are said to have a valency of 1.
Example, sodium, in the alkali metal group, has a valency of 1.
Elements with 7 electrons, are also very reactive.
They are very eager, to receive one electron, to complete the octet.
They are said to have valency of 7.
Example, chlorine in the halogen group has a valency of 7.
Sodium and chlorine, have a strong affinity for each other.
They readily combine to form sodium chloride, or common salt.
The number of electrons in the outer most shell, is a good indicator, of the valency.
Elements in the ’s’ and ‘p’ block, have a valency ranging from 1 to 7.
In the periodic table, these elements are grouped together.
Group 1 and 2 elements, have a valency of 1 and 2.
Group 3 to 12 elements, are called as transition metals.
Their outer most electron, are in the ‘d’ shell.
They do not follow this valency rule.
Group 13 to 17, have a valency of 3, 4, 5, 6, and 7.
Group 18 elements, are noble gases, and have a valency of 0.
Periodic table.
We will consider hydrogen, as a special element.
It does not belong to any group.
Helium, with the atomic number of 2, has two electrons in the ’s’ shell.
It is grouped under group 18, in the periodic table.
Lithium has a atomic number of 3.
It’s electronic configuration, is 1 ’s’ 2, 2 ’s’ 1.
It is the first element in the second period.
It belongs to group 1, and occupies the 1st column.
Group 1, is called as the alkali metal group.
Elements in this group, have a valency of 1.
Beryllium has a atomic number of 4.
It’s electronic configuration, is 1 ’s’ 2, 2 ’s’ 2.
It belongs to group 2.
Group 2, is called as the alkaline earth metals.
Elements in this group, have a valency of 2.
This completes, the ’s’ shell in the second period.
Boron has a atomic number of 5.
It’s electronic configuration, is 1 ’s’ 2, 2 ’s’ 2, 2 ‘p’ 1.
It has no ‘d’ shell electrons, as in group 3 to 12.
It belongs to group 13.
Group 13, is called as the Boron group.
Elements in this group, have a valency of 3.
Carbon has a atomic number of 6.
It’s electronic configuration, is 1 ’s’ 2, 2 ’s’ 2, 2 ‘p’ 2.
It belongs to group 14.
Group 14, is called as the Carbon group.
Elements in this group, have a valency of 4.
Nitrogen has a atomic number of 7.
It’s electronic configuration, is 1 ’s’ 2, 2 ’s’ 2, 2 ‘p’ 3.
It belongs to group 15.
Group 15, is called as the Nitrogen group.
Elements in this group, have a valency of 5.
Oxygen has a atomic number of 8.
It’s electronic configuration, is 1 ’s’ 2, 2 ’s’ 2, 2 ‘p’ 4.
It belongs to group 16.
Group 16 , is called as the Oxygen group.
Elements in this group, have a valency of 6.
Fluorine has a atomic number of 9.
It’s electronic configuration, is 1 ’s’ 2, 2 ’s’ 2, 2 ‘p’ 5.
It belongs to group 17.
Group 17, is called as the Halogen group.
Elements in this group, have a valency of 7.
Neon has a atomic number of 10.
It’s electronic configuration, is 1 ’s’ 2, 2 ’s’ 2, 2 ‘p’ 6.
It belongs to group 18,
Group 18 , is called as the noble gas group.
Elements in this group, have a valency of 0.
This completes, the ‘p’ shell of the second period.
This also completes, the second period of the periodic table.
Sodium has a atomic number of 11.
It is the 1st element, of the 3rd period.
It’s electronic configuration, is 1 ’s’ 2, 2 ’s’ 2, 2 ‘p’ 6, 3 ’s’ 1.
All the elements, coming after Neon, will have a electronic configuration,
of 1 ’s’ 2, 2 ’s’ 2, 2 ‘p’ 6, + additional electrons.
The electronic configuration of Neon, will repeat in the 3rd period.
We can abbreviate, Sodium’s electronic configuration,
as ’N,e’, in brackets, 3 ’s’ 1.
’N,e’, is the symbol of Neon.
We are now using the periodicity, of the periodic table.
Sodium belongs to group 1, alkali metal.
It’s valency is 1.
Magnesium has a atomic number of 12.
It’s electronic configuration, is ’N,e’ in brackets, 3 ’s’ 2.
It belongs to group 2, alkaline earth metal.
It’s valency is 2.
This completes, the ’s’ shell of the third period.
Aluminium has a atomic number of 13.
It’s electronic configuration, is ’N,e’ in brackets, 3 ’s’ 2, 3 ‘p’ 1.
It belongs to group 13, Boron group.
It’s valency is 3.
Silicon has a atomic number of 14.
It’s electronic configuration, is ’N,e’ in brackets, 3 ’s’ 2, 3 ‘p’ 2.
It belongs to group 14, Carbon group.
It’s valency is 4.
Phosphorus has a atomic number of 15.
It’s electronic configuration, is ’N,e’ in brackets, 3 ’s’ 2, 3 ‘p’ 3.
It belongs to group 15, Nitrogen group.
It’s valency is 5.
Sulphur has a atomic number of 16.
It’s electronic configuration, is ’N,e’ in brackets, 3 ’s’ 2, 3 ‘p’ 4.
It belongs to group 16, Oxygen group.
It’s valency is 6.
Chlorine has a atomic number of 17.
It’s electronic configuration, is ’N,e’ in brackets, 3 ’s’ 2, 3 ‘p’ 5.
It belongs to group 17, Halogen group.
It’s valency is 7.
Argon has a atomic number of 18.
It’s electronic configuration, is ’N,e’ in brackets, 3 ’s’ 2, 3 ‘p’ 6.
It belongs to group 18, Noble gas group.
It’s valency is 0.
This completes, the ‘p’ shell of the third period.
This also completes, the third period, of the periodic table.
Elements in the 4th period, will have an electronic configuration,
of Argon, ‘A,r’ in brackets, plus additional electrons.
’A,r’ is the symbol for Argon.
Potassium has a atomic number of 19.
It’s electronic configuration is, ‘A,r’ in brackets, 4 ’s’ 1.
It belongs to group 1, alkali group, valency = 1.
Calcium has a atomic number of 20.
It’s electronic configuration is, ‘A,r’ in brackets, 4 ’s’ 2.
It belongs to group 2, alkali group, valency = 2.
This completes, the ’s’ shell of the fourth period.
Scandium has a atomic number of 21.
It’s electronic configuration is, ‘A,r’ in brackets, 4 ’s’ 2, 3 ‘d’ 1.
It belongs to group 3, the transition metal group.
Titanium has a atomic number of 22.
It’s electronic configuration is, ‘A,r’ in brackets, 4 ’s’ 2, 3 ‘d’ 2.
It belongs to group 4, the transition metal group.
Similarly, we can place other elements.
Iron has a atomic number of 26.
It’s electronic configuration is, ‘A,r’ in brackets, 4 ’s’ 2, 3 ‘d’ 6.
It belongs to group 8, the transition metal group.
Copper has a atomic number of 29.
It’s electronic configuration is, ‘A,r’ in brackets, 4 ’s’ 2, 3 ‘d’ 9.
It belongs to group 11, the transition metal group.
Zinc has a atomic number of 30.
It’s electronic configuration is, ‘A,r’ in brackets, 4 ’s’ 2, 3 ‘d’ 10.
It belongs to group 12, the transition metal group.
Zinc is the last transition element in the fourth period.
Bromine has a atomic number of 35.
It’s electronic configuration is, ‘A,r’ in brackets, 4 ’s’ 2, 3 ‘d’ 10, 4 ‘p’ 5.
It belongs to group 17, Halogen group, valency =7.
Krypton has a atomic number of 36.
It’s electronic configuration is, ‘A,r’ in brackets, 4 ’s’ 2, 3 ‘d’ 10, 4 ‘p’ 6.
It belongs to group 18, Noble gas group, valency = 0.
This completes, the ‘p’ shell, of the fourth period.
This also completes, the fourth period.
We can now understand, the symmetry, underlying the periodic table.
We can similarly place, the other elements, in the periodic table.
Electrons occupy the shells, in the same order.
This order is given by the Madelung, or the diagonal rule.
We would have also noticed, that the electron configuration, of the heavier elements,
can be built upon, the electron configuration of the noble gases.
The electron configuration of the noble gases are:
Neon : 1 ’s’ 2, 2 ’s’ 2, 2 ‘p’ 6.
Argon is : Neon + 3 ’s’ 2, 3 ‘p’ 6.
Krypton is : Argon + 4 ’s’ 2, 3 ‘d’ 10, 4 ‘p’ 6.
Xenon is : Krypton + 5 ’s’ 2, 4 ‘d’ 10, 5 ‘p’ 6.
Radon is : Xenon + 6 ’s’ 2, 4 ‘f’ 14, 5 ‘d’ 10, 6 ‘p’ 6.
Knowing which group, an element belongs to, in a periodic group,
we can find, some common properties, of elements in that group.
Metalloids.
We can identify, metals and non metals, from the periodic table.
Metalloids are in-between metals, and non metals.
They exhibit some characteristics, of metals, and some characteristics, of non metals.
Boron, Silicon, Germanium, Arsenic, Antimony, and Tellurium,
and Astatine are metalloids.
They form a step like structure, in the periodic table.
Metalloids are the dividing line, between metals and non metals.
Elements to the left of the metalloids are metals.
Elements to the right of the metalloids are non metals.
Silicon, is a well known metalloid.
It is a semi conductor, widely used to make electronic chips.
Like a typical metalloid, it is a part conductor, and a part insulator.
That is why, it is called as a semi conductor.
Metals.
Metals are found, in the left side of the periodic table.
Metals have some common characteristics.
These characteristics are typical, with a few exceptions.
They are hard.
They are opaque.
They are shiny.
They are good conductors of heat.
They are good conductors of electricity.
They are malleable.
That is, they can be formed into many shapes, for example, like in gold jewellery.
They are ductile.
That is they can be drawn, into a thin wire,
for example, like in aluminium, or copper wire.
They are fusible, that is they can be melted.
Metals react with Oxygen, to form metal oxides.
About 91 elements, in the periodic table, are metals.
Non metals.
Non metals, are highly volatile, that is they can be easily vaporised.
Many non metals, are gaseous in nature.
They have low elasticity.
They are thermal insulators.
They are electrical insulators.
They form compounds, by gaining or sharing electrons, with other elements.
They form many more compounds, then metals.
Living organisms, mostly comprise of compounds of non metals.
Hydrogen, Helium, Nitrogen, Oxygen, Neon, Chlorine,
are examples of non metallic gases.
Carbon, Phosphorus, Sulphur, Iodine, are examples of non metallic solids.
There are about 17 non metals, in the periodic table.
Though non metals are in a minority, they make up this, with their abundance.
About 99% of the universe, is comprised of hydrogen and helium.
This is because, all the stars are comprised, of mostly Hydrogen, and Helium.
They are the primordial elements.
Alkali Metals.
Alkali metals is the first group in the periodic table.
Sodium and potassium are examples, of alkali metals.
They belong to the ’s’ block.
They have one electron in the ’s’ sub shell.
They are ever ready, to donate their outer most electron,
and become a cation, with a charge of + 1.
This is also called as an oxidation number of +1.
They are shiny and soft.
We can cut a alkali metal with a knife.
They are very highly reactive.
They readily react with Oxygen, to form oxides.
They are only found in salt compounds, in the natural state.
For example, Sodium chloride.
Alkaline earth metals.
Alkaline earth metals, are the second group in the periodic table.
They belong to the ’s’ block.
They have 2 electrons, in the ’s’ block.
They readily donate their outer most 2 electrons,
to become a cation, with a charge of + 2.
This is also called as an oxidation number of +2.
Magnesium and calcium, are examples of alkaline earth metals.
Transition metals.
They belong to group 3 to 12, of the periodic table.
They belong to the ‘d’ block.
Elements in this block, can exhibit variable valency.
Titanium, Iron, Nickel, Copper, Zinc, Silver, Tungsten, Platinum, Gold,
are examples of transition metals.
Boron group.
They belong to group 13, of the periodic table.
They belong to the ‘p’ block.
They have an outer electronic configuration, of ’s’ 2, ‘p’ 1.
Aluminium belongs to this group.
Carbon group.
They belong to group 14, of the periodic table.
They belong to the ‘p’ block.
They have an outer electronic configuration, of ’s’ 2, ‘p’ 2.
Carbon, tin, and lead are some members of this group.
Nitrogen group.
They belong to group 15, of the periodic table.
They belong to the ‘p’ block.
They have an outer electronic configuration, of ’s’ 2, ‘p’ 3.
Nitrogen and phosphorus are some members of this group.
Oxygen group.
They belong to group 16, of the periodic table.
They belong to the ‘p’ block.
They have an outer electronic configuration, of ’s’ 2, ‘p’ 4.
Oxygen and sulphur, are some members of this group.
Halogens.
They belong to group 17, of the periodic table.
They belong to the ‘p’ block.
They have an outer electronic configuration, of ’s’ 2, ‘p’ 5.
Halogens are highly reactive.
They are always on the lookout, for an extra electron,
to complete an octet, of 8 electrons, in the outer shell.
Fluorine, Chlorine, Bromine, and Iodine, are some members of this group.
Not surprisingly, members of this group, have a strong affinity,
for members of the alkali metal group.
This is because, alkali metals have 1 electron in the outer most shell.
Sodium chloride, is an example of a compound, formed with the combination,
of a alkali metal and a halogen.
Noble gases.
They belong to group 18, of the periodic table.
They belong to the ‘p’ block.
They have an outer electronic configuration, of ’s’ 2, ‘p’ 6.
Noble gases are inert.
Their outer electron shell, has an octet of 8 electrons.
They do not easily react, with other elements, to form compounds.
Noble gases, are the last group, of elements, in a period,
of the periodic table.
The next element after the noble gas, will start in a new period.
Lanthanides.
The elements with atomic number, 57 to 70, belong to the 1st bottom row,
of the periodic table.
They can be be broadly called as Lanthanides.
They belong to the ‘f’ block.
They are represented, as a separate group,
below the main periodic table.
This is more convenient way of representation.
It reduces the width of the periodic table, makes it more easily readable.
They were originally called as, rare earth elements.
Most of them are not commonly found, or used.
Cerium, is an example of an element in this group.
Actinides.
The elements with atomic number 89 to 102, belong to 2nd bottom row,
of the periodic table.
They can be broadly called as Actinides.
They belong to the ‘f’ block.
They are represented, as a separate group, below Bottom row 1 elements.
Lanthanides and actinides, can be considered as the two rows of elements,
at the bottom of the periodic table.
The naming convention, has a couple of exceptions.
Actinides, are heavy elements.
They are radio active.
They undergo radio active decay.
Thorium and Uranium, are naturally occurring actinides.
The rest of them are synthetically created, in nuclear laboratories.
Plutonium, is an example of synthetically produced actinide.
Thorium, Uranium, and Plutonium are used in nuclear reactors.
Nuclear reactors, are used to produce, electrical energy.
Radio active elements, like uranium, are also used to produce nuclear weapons.
Synthetic elements.
All the heavier elements, after Plutonium, with atomic number greater than 94,
are only synthetically produced, in a nuclear laboratory.
They are very unstable elements.
They exist only for a short period of time.
They do not exhibit, any known chemical properties.
The existence of synthetic elements, is confined to the nuclear laboratory.
The last element in the periodic table, is Ununoctium.
It has an atomic number of 118.
It is very unstable, and very little is known about it.
These elements are of interest, to nuclear scientists.