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NATA 2020 CHEMISTRY Syllabus (Updated)

NATA 2020 CHEMISTRY Syllabus (Updated)

Topic - 1

Structure of Atom

Matter is made up of tiny particles called atoms. An atom consists of a heavy positively
charged nucleus. The whole mass of the atom is concentrated in the nucleus. The electrons
in an atom revolve around the nucleus in definite circular paths called orbits or energy level.
Each energy level is associated with definite amount of energy. Atoms are further made of
three fundamental particles or sub–atomic particles called electron, proton and neutron.

Types of Sub-atomic Particles

Discovery of Sub- atomic Particles

(a) Electron (e-):

These negatively charged particles were discovered by J. J. Thomson in 1897. In the
experiment, a gas at low pressure was taken in a discharge tube made up of glass. At the ends
of the discharge tube two electrodes were placed, connected to a battery for high voltage
supply. The electrode connected to the negative end was known as cathode and that to the
positive as anode. He then observed a stream of negatively charged particles coming out of
cathode towards the anode. These particles were called electrons.
The collection of negatively charged particles emitted from the cathode of the discharge tube
is called cathode rays.

(b) Proton (p+):
In 1886, Goldstein observed in the same experiment, with different situations that the anode
emitted positive particles which were called Canal rays. The positively charged radiations
produced in the discharge tube from anode are called Canal rays.

(c) Neutron (n):
These neutrally charged particles were discovered by James Chadwick in 1932. Neutrons are
present in atoms of all elements except Hydrogen.

Various models explaining structure of an atom:
1. Thomson’s Model of an atom
It is also known as Thomson’s plum pudding model. In 1903 J. J. Thomson proposed the
structure of an atom.

He proposed:
● An atom is a positively charged sphere and the electrons are embedded in it.
● The Magnitude of positive and negative charge is the same inside an atom, so net
charge inside an atom is zero.

2. Rutherford’s “α- particle scattering experiment”
Rutherford designed an experiment called The Nuclear model of an atom.

According to Nuclear model of an atom:
● Most of the space inside the atom is empty.
● At the Centre of an atom, a small, heavy, positively charged nucleus is present.
● Electrons revolve around the nucleus.
● Total positive charge in nucleus is same as total negative charge on all electrons of an
atom as the atom has net zero charge.

3. Bohr’s Model of Atom
In 1913, Neil Bohr overcame the limitations of Rutherford model and proposed a model of
atomic structure.

Following are the postulates:
1. Electrons revolve around a centrally located heavy small and positively charged
nucleus in certain discrete orbits.
2. While revolving in discrete orbits the electrons do not radiate energy.
3. These discrete orbits or shells are called energy levels. These orbitals or shells are
represented by the letters K, L, M, N… or the numbers, n = 1, 2, 3, 4…

Atomic Number
The number of protons present in the nucleus of an atom is called atomic number. It is
denoted by Z.

For atoms:
Atomic number = number of proton = number of electron

For ions:
Atomic number = number of proton ≠ number of electron

Mass number
Mass number is equal to the number of nucleons present inside the nucleus of an atom. It
means it is the sum of the number of protons and neutrons present in the nucleus of an atom.
It is denoted by letter A.

Mass number of element = Atomic mass of element = number of protons + number of
The symbol of the element with atomic number and mass number :

Isotopes are atoms of same element having same number of protons but different number of
neutrons. Isotopes have similar chemical properties but different physical properties.

Uses of Isotopes:
1. An Isotope of uranium (235
Ur) is used in nuclear power plants to generate electricity.
2. Used for medical purposes:
● An Isotope of cobalt is used in the treatment of cancer.
● An isotope of iodine is used in the treatment of goiter.
IsobarsIsobars are atoms having different number of protons but same number of nucleons (number
of protons + number of electrons). For example, Argon and Calcium have different atomic
number but the same mass number.

Valency of an element is the number of electrons that its atoms should give away or take to
attain stable electronic configuration i.e. the atom should accommodate 8 electrons in the
outermost shells or valence shells except the K shell which can accommodate 2 electrons to
the maximum.
The electrons present in the outermost orbit of an atom are known as valence electrons.
Three ways to obtain stable electronic configuration:
(a) By losing electrons
(b) By Gaining electrons
(c) By sharing electrons

Topic - 2

Heading - 2

Classification of objects and objects during periods of buildings

Classification of Material
With the discovery of a large number of elements, it was difficult to study the elements
individually, so classification is done to facilitate learning. Many attempts
they were meant to distinguish the known things from time to time. Previous attempts are as follows
the following:

Prout's Hypothesis (1815)
According to this theory, a hydrogen atom was considered to be the basic unit from which it came
all other atoms are made. It is also known as a superstition.

Doadsiner's Triads (1829)
Dobereiner divided the elements into groups of three with similar elements inside
the way that the atomic weight of the central element was arithmetic
and two others.

Limitations: Dobereiner was not able to arrange all the items known then as competitors.
He could only point to the triangles as in the drawing.

Newland's Octave (1864) (Octave Law
Newland says that when things are organized in order of increasing mass of atoms, they are each
the eighth item has the same properties as the first one in the music text [Every eighth
the music note 1S is the same as the note mentioned earlier].
1. This separation was successful up to calcium calcium.
2. When good elements are discovered over time, their incorporation into these characters
interrupt the whole system.

Lother Meyer's Atomic Volume Curve (1869)
Meyer introduced the separation of objects in a point-to-point manner between atomic volume
and atomic metals and imply that the properties of elements are a function of time
of their atomic numbers.
[Here, atomic volume = cell / human sounds
He concluded that elements with the same structure have the same location in the curve.

Mendeleef time table
The Mendeleefs time table is based on Mendeleef's contemporary law 'Physical
and the chemical properties of the elements are a temporary function of their thousands of atoms. ”
At the time of Mendeleef, only 63 were known.
This Period Column is divided into seven rows (periods) with eight layers
(groups). The Zero Group was later added to the modified Mendeleords Periodic table.

Present Table (1913)
Moseley amended Mendeleef's interim law. “Physical and chemical properties of
periodic activity elements of their atomic numbers. ”It is known as the modern periodic period
rule and considered to be the basis of the End Times Table.
When things were arranged in order of atomic numbers, it was noticed
that the structures of the elements were repeated after certain regular intervals 01 2, 8, 8, 18, 18
and 32. These numbers are called magical numbers and the reason for the occurrence of times in the right circumstances
repeating the same electronic configuration.
Structural Features of Long Form of Time Table

1. The long form of the time table is called Bohr's Periodic Table. There are 18 teams and seven
periods in this time table

2. Horizontal lines are called periods.
● The initial period (1H - 2He) consists of 2 elements. The shortest time
● The second period (3Li - 10Ne) and the third period (11 Na - 18Ar) contain individual elements.
These are shorter times.
● The fourth season (19K - 36Kr) and the fifth season (37Rb - 54Xe) contain 18 items each.
These are long times.
● The sixth time (55Cs - 86 Rn) contains 32 items and is the longest.
● The seventh season starting with 87Fr is incomplete and contains 19 items.

3. The 18th vertical columns are known as groups.
● Group 1arc substances called alkali metals.
● The elements of group 2 are called alkaline metals.
● The components of group 16 are called chalcogen [ore element elements].
● Components of group 17 are called halogeners. [sea salt]
● Parts of group 18 are called good gases.
The ridiculous behavior of the first party item
The first element of a group is quite different from its congeners (e.g., res., the rest of the
elements of its group).
This is due to (I) small size (ii) high electronegativity and (iii) non availability of orbitals for
bonding. Anomalous behavior is observed among the second-row elements (i.e., Li to F).

4. The Periodic Table is divided into foul’ main blocks (s, p, d and n depending upon the
subshell to which the valence electron enters into.
(a) s-block elements Ist and IInd group elements belong to this block and the last electron
enters in s-subshell.
General electronic configuration is ns1 – 2
(b) p-block elements Group 13th to 18th belong to this block in which last electron enters
in p-orbital.

General electronic configuration is ns2 np1 – 6
This is the only block which contains metal, non-metal and metalloids. Examples of metalloids
are B, SI Ge, As, Sb, Te and At.
The elements of s-and p-block elements are collectively called representative elements.
(c) d-block elements Group 3rd to 12th belong to this block, in which last electron enters in
d-orbit. They have inner incomplete shell. so known as transition elements.
General electronic configuration is ns1 – 2 (n – 1)d1 – 10
d-block elements are generally colored, paramagnetic and exhibit variable valency.
(d) f-block elements They constitute two series 4f (lanthanoids) and 5f (actinides) in which
last electron is in 4f and 5f subshell respectively.
General electronic configuration (n – 2) f1 – 14(n – 1) d0 – 1 ns2
The f-block elements are also called as inner-transition elements.
(Elements with atomic number greater than 92 (U92) are called the trans uranium elements.
All these elements are man-made through artificial nuclear reactions.
Very recently. on August 16, 2003, IUPAC approved the name for the element of atomic
number 110, as Darmstadtium, with symbol Ds].

Limitations of Long Form of Periodic Table
In the long form of the Periodic Table :
1. The position of hydrogen still remains uncertain.
2. The inner-transition elements do not find a place in the main body of the table. They are
placed separately.

Predicting the Position of an Element in the Periodic Table

First of all write the complete electronic configuration. The principle quantum number of the
valence shell represents the period of the element. The subshell in which the last electron is
filled corresponds to the block of the element.
Group of the element is predicted from the electrons present in the outermost (n) or
penultimate (n -1) shell as follows:
For s-block elements: group number = number of ns-electrons
For p-block elements: group number = 10 + number of ns and np electrons
For d-block elements: group number = the sum of the number of (n -1) d and ns electrons.
For f-block elements; group number is 3.

Periodic Properties
The properties which are directly or indirectly related to their electronic configuration and
show gradual change when we move from left to right in a period or from top to bottom in a
group are called periodic properties.
Atomic Radius
It is the distance from the centre of the nucleus to the outermost shell of electrons. Covalent
radius for an atom A in a molecule A2
rA = rA + rA / 2 = dA – A / 2
For heteroatomic molecule AB,
dA – B = rA + rB + 0.009 (XA – XB) where, XA and XB are electronegativities of A and B.
In general, the atomic size decreases on moving from left to right in a period due to increase
in effective nuclear charge and increases on moving from top to bottom in a group due to
addition of new shells.
van der Waals’ Radius
It is defined as one-half of the distance between the nuclei of two non – bonded isolated
atoms or two adjacent atoms belonging to two neighboring molecules of an element in the
solid state.

Metallic Radius

It is defined as the one-dimensional distance between the centers of the nuclei of two adjacent atoms

in a metal crystal.

Ionic Radius

An atom can be converted into a cation by 10RS of electrons and anion by electrons.

The cation is always smaller than the parent atom because during its strong nuclear formation

the value goes up and sometimes the shell can also shrink. On the other hand, the size of

anion is always larger than the parent atom because during its strong nuclear formation

the charge is reduced.

In the case of ioncticion ions, you are too high for the nuclear charge. it is small in size. e.g., AI3 <Mg2 +

<Na + <f– <O2- <N3-

The order of the radiation can be radius <van der Waals' metal radio

Ion Enthalpy (IE)

It is the amount of energy required to remove an electron that has been unwantedly bound to one another

the gaseous atom.

A (g) + IE → A + (g) + e--

The various features of the IE vanes are:

(i) atom size. it varies

(ii) Examination result: varies

(iii) Nuclear costs: they are quite different

Generally left to right times the ionization enthalpy increase; the lower the group, the lower it gets.

IE values ​​of the input voltage are particularly high due to the stable suspension.

Effective enthalpies IE3> IE2> IE1

IE1 for N is larger than that for oxygen because of its stable half - saturated with 2p-orbitals.

Among the 3d series switches, 24Cr and 29Cu have higher IE2 due to partial overlap and

fully saturated d-orbitals

Electron Gain Enthalpy (EGE or ΔHe g)

The amount of energy released when an electron is attached to an isolated gaseous atom.

The first electronics that received the enthalpy were fun while the other electronics in the series found themselves in love

be optimistic due to the precipitation between the electrons already present in the anion and

an electron is inserted.

The various factors in which an electron detects enthalpy variations are:

(i) Atomic size: varies directly

(ii) Nuclear Fees: varies directly

Over time, the electrons gain in the enthalpy become worse as they move

the lower the group, the less negative it becomes.

Noble gases have good electronics that absorb enthalpies.

Halogens have a maximum value of ΔHe g at a time because of the small size of the atom.

F and Atom have smaller size and larger charge charge, and therefore have lower electron gain

enthalpy, than Cl and S respectively Cl> F; S> O

Elements with half orbitals that are half full and well packed show extra stability. therefore, electrons

enthalpy will be less than that.

The enthalpy electrons can be measured in aorn-Haber cycle with objects with a high ΔHe g

is a good oxidizing agent.

Electronegativity (EN)

It is defined as the tendency of an atom to attract an electron that has been distributed to the target itself

a joint obligation. The various aspects of electronegativity are:

(i) Atomic size: varies widely

(ii) Charging on the ion: it varies directly, e.g., Li <Li +, Fe2 + <Fe3 +

(iii) Hybridization: (Electronegativity & infi; s-character in the hybrid orbital)

The electronegativity of a carbon atom = C2H6 <C2H4 <C2H2

In times as we move from left to right there is an increase in energy, while we are in a group

electronegativity lowers the group.

For good gases, its value is assumed to be zero.

Electronegativity helps to predict bond formation and bonding time of molecules.

Order electronics for specific items (on Paul scale)

(i) Unpleasant scale

Electronegativity (x) = IE + ΔHe g / 2

(ii) Paul's scale the difference in the electron density of the two atoms A and Bis provided by


xB - xA = 0.18 √√

where, Δ = EA - B - √EA - A * EB - B

(Δ is known as resonance energy.)

EA - B, EA - A and EB - B represent the bond dissociation energies of A - B, A - A and

B - B respectively.

(iii) The method used with Randow

Electronegativity = 0.744 + 0.359 Zeff / r2

where, Zeff is an effective cost function = Z - σ

where, σ is always evaluated. The value can be seen


It is defined as the capacity to assemble an item. The size of the item is related

the electronic atom configuration and is usually determined by the electrons present in the

the valence shell.

Over time from left to right, valency increases from 1 to 4 and then decreases

rising to zero (positive gases) while moving down the group the sovereignty remains the same.

Variable metals show a wide range of differences because they too can use electrons (external ones of love

like an invisible shell.

The chemical reactions

Metal reuse increases with decreasing IE, electronegativity and atomic size

and the electropositive character.

The use of non-negative metals increases with increasing electronic power and electron gain

enthalpy and decrease of atomic radii.

Brushing and baking points

When lowering the group, the melting point and the boiling point of the metal material continue

it decreases because of the diminished power of attraction. However, for non-metals, the melting point

and the boiling point usually boosts down the party.

[As well as the time from left to right, the melting point and boiling point increases and reaches a

maximum during the period and begin to decrease].

Tungsten (W) has the highest mp. (3683K) among metals, carbon (diamond) has the highest m..p,

(4000 K) between non-metals.

Li iron has the minimum density while iridium (Ir) iron has the highest density.

Electropositivity or Metallic Character

The tendency for an organ atom to lose valence electrons and to form ion ions is

called electropositivity. The electropositive character is big, big


Electropositive character decreases over time and increases in motion

down the group. Alkali metals are very electropositive and small halogens

an electropositive object in its time.

The basic nature of iron oxides, i.e., also decreases over time and increases

down the group.

Diagonal Relationships

Certain 2-time objects show similarities in structures with their diagonal elements in

season 3 as shown below:

Thus, Li resembles Mg, Be resembles Al and B resembles Si. This is called diagonal relationship
and is due to the reason that these pairs of elements have almost identical ionic radii and
polarizing power (i.e., charge/size ratio). Elements of third period, i.e., Mg, Al and Si are
known as bridge elements.

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