This document provides an overview of chemistry concepts including: - Chemistry is the study of matter and changes in matter. It includes fields like analytical chemistry, physical chemistry, biochemistry, organic chemistry, and inorganic chemistry. - Atoms are the smallest particles that make up elements. They consist of protons, neutrons, and electrons. Ions are formed when atoms gain or lose electrons. - Molecules are formed when atoms bond together through ionic bonds, covalent bonds, or coordinate bonds. Ionic bonds involve electron transfer between ions. Covalent bonds involve electron sharing between atoms. Coordinate bonds involve one-sided electron sharing. - Chemical bonds allow atoms to attain stable electron configurations like the noble gas configuration

1. Course: Diploma
Subject: Applied science(Chemistry)
Unit: I

2. Chemistry is the study of
matter and study of the changes that matter undergoes.

3. Analytical Chemistry
Physical Chemistry
Biochemistry
Organic Chemistry
Inorganic Chemistry

4. In our surroundings
Medicine
Industry
Research
Environmental Issues

5. A microscopic small particle that could not be made any
smaller and still behave as a chemical system. Atoms are the
smallest particles that can exist .
 Atoms cannot be created or destroyed.

6. 3

7. Particle
Mass
(g)
Charge
(Coulombs)
Charge
(units)
Electron (e-
) 9.1 x 10-28
-1.6 x 10-19
-1
Proton (p) 1.67 x 10-24
+1.6 x 10-19
+1
Neutron (n) 1.67 x 10-24
0 0

8. Small negatively charged particle
 Orbit, circle, around the nucleus
Atoms are neutral
Number of electrons = number of protons

9. small, positively charged particles
reside in the nucleus along with the neutron
 make up most of the mass of the atom
the number of protons is what defines the type of a
particular atom.
number of protons = number of electrons

10. small particles with no charge
reside in the nucleus
along with the proton, make up most of the
mass of the atom

11. A molecule is an aggregate of two or more atoms
in a definite arrangement held together by chemical
bonds.
H2
H2O NH3 CH4

12. A Diatomic molecule contains only two atoms
H2, N2, O2, Br2, HCl, CO
A Polyatomic molecule contains more than two
atoms.
O3, H2O, NH3, CH4
2

13. 4

14. An ion is an atom, or group of atoms, that has a net positive or
negative charge.

15. Cation – ion with a positive charge
If a neutral atom loses one or more electrons
it becomes a cation.
Na 11 protons
11 electrons
Na+ 11 protons
10 electrons
Anion – ion with a negative charge
If a neutral atom gains one or more electrons
it becomes an anion.
Cl 17 protons
17 electrons
Cl- 17 protons
18 electrons

16. A monatomic ion contains only one atom
Na+, Cl-, Ca2+, O2-, Al3+, N3-
A polyatomic ion contains more than one atom
OH-, CN-, NH4
+, NO3
-
Ionic compounds
ionic compounds consist of a cation and an anion
• the formula is always the same as the empirical formula
• the sum of the charges on the cation and anion in each
formula unit must equal zero

17. NaCl
5

18. Ionic Compounds
often a metal + nonmetal
anion (nonmetal), add “ide” to element name
BaCl2 barium chloride
K2O potassium oxide
Mg(OH)2
KNO3
magnesium hydroxide
potassium nitrate

19. Atomic number (Z) = number of protons in nucleus
Mass number (A) = number of protons + number of neutrons
= atomic number (Z) + number of neutrons
Isotopes are atoms of the same element (X) with different numbers of
neutrons in the nucleus.
XA
Z
H1
1 H (D)2
1 H (T)3
1
U235
92 U238
92
Mass Number
Atomic Number
Element Symbol

20. Molecular Formula Definition: An expression which states the
number and type of atoms present in a molecule of a substance.
Example: There are 6 C atoms and 14 H atoms in
a hexane molecule, which has a molecular formula of
C6H14.

21. Molecules of chemical substances are made of two or more
atoms joined togather by some force, acting between them. This
force which results from the interaction between two or more
atoms that go to form a stable molecule, is referred to as a
chemical Bond.
A Chemical bond is defined as a force that
acts between two or more atoms to hold them
together as a stable molecule.

22.  The term valence or valency is often used to state that
potential or capacity of an element to combine with other
elements.
For an example in HCl ,one atom of chlorine is combined with
one atom of hydrogen and the valency of chlorine is 1.
Valence or valency is the number of
bonds formed by an atom in a molecule.

23. The valence electrons which actually involves in
bond formation are called Bonding electrons.
The remaining valence electrons are referred to
as non bonding electrons.
Valence
Bonding
Electrons
Non bonding
Electrons

24. G.N.Lewis and w.Kossel gave electronic theory
of valence and explained why atoms join to form
molecules.
Noble gas atoms had a stable electronic
configuration and others have unstable or
incomplete configuration.
It states that: In chemical bond formtion ,atoms
interact by losing,gaining,or sharing of
electrons so as to acquire a stable noble gas
configuration.

25. Atoms of noble gas possess a stable outer shell
of 8 electrons or octet.
Electronic theory of valence also termed as octet
theory of valence/ Rule of octet.
It may be stated as :
Atoms interact by electron sharing or electron
transfer, so as to achieve the stable outer shell of
eight electrons.
It also known as Rule of eight.

27. The type of chemical bond developed between the
two combining atoms depends upon the way
these atoms acquire a stable noble gas
configuration.
Elements may combine through any one of the
following ways to form stable compounds.
i. By the transfer of electrons from the atom of an
element to the atom or atoms of another. This
gives rise to an ionic (or electrovalent) bond.
ii. By mutually sharing the electrons. This gives
rise to a covalent bond.
iii. By one-sided sharing of electrons. This gives
rise to a coordinate bond.

28. This type of bond is established by transfer of
an electron from one atom to another.
In an ionic bond, one atom loses an electron
to another atom, forming a cation and anion,
respectively. And, they attract towards each
other ,by electrostatic attraction they combined
togather.
An IONIC BOND is an electrostatic
interaction that holds together a positively
charged ion (cation) and a negatively
charged ion (anion).

29. Formation of Ions
A has one electron in excess and B has one electron short than the stable
octet.
Therefore, A transfers an electron to B and in this transaction both
atoms acquire stable electronic configuration.
And they held togather by electrostatic attraction.

31. In table salt, for example, a valence electron from a sodium
atom is transferred to a chlorine atom, forming Na+ and Cl-.
Because the ions have opposite charges, they are attracted
to each other. The loss of a valence electron and the
attraction to the atom that took it happen simultaneously.
4

32. A covalent bond is formed between two atoms
(similar or dissimilar) by a mutual sharing of
electrons. The shared pairs of electrons are counted
towards the stability of both the participating atoms.
A covalent bond is defined as the force of
attraction arising due to mutual sharing of
electrons between the two atoms.
The combining atoms may share one, two or three
pairs of electrons.

33. When the two atoms combine by mutual sharing of
electrons, then each of the atoms acquires stable configuration
of the nearest noble gas. The compounds formed due to
covalent bonding are called covalent compounds.
Covalency
The number of electrons which an atom contributes towards
mutual sharing during the formation of a chemical bond is
called its covalency in that compound.
Thus, the covalency of hydrogen in H2 (H - H) is one; that of
oxygen in O2 is two (O = O), and that of nitrogen in N2 is three
(N  N).

34. Single Covalent Bond
A covalent bond formed by mutual sharing of one pair of
electrons is called a single covalent bond, or simply a
single bond.
A single covalent bond is represented by a small line (-)
between the two atoms.

35. Formation of ammonia (NH3)
The electronic configurations of nitrogen and hydrogen
are
N 1s2 2s2 2p3 or 2,5
H 1s1 or 1
Thus, each nitrogen atom requires three more electrons to
acquire a stable noble gas configuration. On the other
hand, each H-atom requires only one electron to achieve
the stable helium configuration. This is done by mutually
sharing three pairs of electrons between one nitrogen and
three hydrogen atoms, as shown below.

36. MULTIPLE COVALENT BONDS:
The covalent bonds developed due to mutual
sharing of more than one pairs of electrons are
termed multiple covalent bonds. These are,
Double covalent bond.
The bond formed between two atoms due to the
sharing of two electron-pairs is called a double
covalent bond or simply a double bond. It is
denoted by two small horizontal lines (=) drawn
between the two atoms,
e.g., O = O, O = C = O etc.

37. Triple covalent bond.
Bond formed due to the sharing of
three electron-pairs is called a triple
covalent bond or simply a triple bond.
Three small horizontal lines between
the two atoms denote a triple bond,
e.g., N  N, and H - C  C H
(acetylene).

38. 4

39. Coordinate bond is formed when the shared electron-
pair is provided by one of the combining atoms.
The atom which provides the electron-pair is termed as
the donor atom, while the other atom which accepts it, is
termed as the acceptor atom.
The bond formed when one-sided sharing of
electrons take place is called a coordinate bond. Such
a bond is also known as dative bond. A coordinate bond is
represented by an arrow () pointing towards the
acceptor atom.

40. Ammonium (NH4
+) ion
During the formation of ammonium ion, nitrogen is the donor atom,
while H+ is the acceptor ion as shown below.
5

41. Polar covalent Bond
A covalent bond in which electrons are shared
unequally and the bonded atoms acquire a partial positive
and negative charge ,is called a polar covalent bond.
Nonpolar covalent bond
A covalent bond in which electrons are equally
distributed ,the + and – charge are equal proportion
which makes atoms neutral ,is called nonpolar covalent
bond.

42. If a hydrogen atom is bonded to a highly electronegative
element such as fluorine, oxygen, nitrogen, then the shared pair
of electrons lies more towards the electronegative element. This
leads to a polarity in the bond in such a way that a slight positive
charge gets developed on H-atom, viz.,
H+ d : O- d H+ d : F- d H+ d : N- d
This positive charge on hydrogen can exert electrostatic
attraction on the negatively charged electronegative atom of the
same or the other molecule forming a bridge-like structure such
as
Xd - - Hd+ × × × × × × Yd- - Hd+
where X and Y are the atoms of strongly electronegative
elements.
The bond between the hydrogen atom of one molecule
and a more electronegative atom of the same or another
molecule is called hydrogen bond.

43. Hydrogen fluoride (HF).
Water (H2O).

45. (a) Intermolecular hydrogen
bonding
When the hydrogen bonding is between the H-atom of
one molecule and an atom of the electronegative
element of another molecule, it is termed as
intermolecular hydrogen bonding. For example,
hydrogen bonding in water, ammonia etc., is
intermolecular hydrogen bonding.

46. (b) Intramolecular hydrogen
bonding
The intramolecular hydrogen bonding is between the
hydrogen of one functional group, and the electronegative
atom of the adjacent functional group in the same molecule.
For example, the molecule of o-nitrophenol, shows
intramolecular hydrogen bonding. The p-nitrophenol shows
intermolecular hydrogen bonding.

47. The peculiar type of bonding which holds the atoms
togather in metal crystal is called The Metallic Bonding.
5

48. The relatively weak attractive forces that act on neutral atoms
and that arise because of the electric polarization induced in
each of the particles by the presence of other particles.
Inter molecular: between molecules (not a bond)
Intra molecular: bonds within molecules(stronger)

49. 1) dipole-dipole
2) dipole-induced dipole
3) dispersion

50. -Two polar molecules align so that d+
and d- are matched (electrostatic
attraction)
Ex: ethane (C2H6) vs. fluromethane
(CH3F)

51. Fluoromethane (CH3F)
H H
H C F H C F
H H
d-
d-d+ d+
Ethane (C2H6)
H H H H
H C C H H C C H
H H H H
Dipole-Dipole
NOT Dipole-Dipole

52. A dipole can induce (cause) a
temporary dipole to form in a non-
polar molecule
The molecules then line up to
match d+ and d- charges.

53. Example:
H Cld+ d- Are-
e-
e-
e-
e-
e-
e-
e- e-
e-
e- e-
e-
e-
e-
e-
e-
e-
A DIPOLE
(it’s polar)
non-polar
INDUCED
DIPOLE
d-d+
Dipole – Induced Dipole
(weak and short-lived)

54. A temporary dipole forms in a
non-polar molecule…
which leads to…
a temporary dipole to form in ANOTHER
non-polar molecule
Dispersion is the ONLY intermolecular
attraction that occurs between non-polar
molecules

55. Example:
Cl-Cle-
e-
e-
e-
e-
e-
e- e-
e-
e-
e-
e-
e-
e-e-
e-
e-
e-
non-polarINDUCED
DIPOLE
d-d+
TEMPORARY
DIPOLE
non-polar
Cl-Cle-
e-
e-
e-
e-
e-e- e-
e-
e-
e-
e-
e-
e-
e-
e- e-
d-d+
Dispersion
(weakest and very short-lived)
1

56. References
1. Essentials of Physical chemistry by Bahl & Tuli
2. Elements of Physical chemistry by Glass ton & Lewis
3.http://www.howstuffworks.com
4.http://www.wpclipart.com/energy/atom/atomic_struc
ture.png.html
5.http://www.en.wikipedia.org
6. http://meddic.jp/metallic_bond