Engineering Chemistry-I-Unit I

1. M-SCHEME
8/16/2016
Dr.M.Govindarajan&
Dr.T.S.Malarvizhi
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2. ATOMIC STRUCTURE
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3.  The smallest particle of an element,
chemically indivisible and that can take part
in chemical reactions.
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4.  The central part of an atom called nucleus. It
contains proton,a positively charged particle
and a neutral particle called neutron
 Around the nucleus the electrons revolve
around definite paths called shells viz. K, L,
M, N etc.
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P
N

5. Charge Mass(Atomic mass
unit)
Proton +1 1
Electron -1 Negligible
Nuetron 0 1
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7.  Number of protons or the number of
electrons present in an atom denoted ‘Z’
 Eg. 11Na
 There are 11 protons and 11 electrons.
 There are 11 postively charged particles and
11 negatively charged particles.
 As a whole an atom is always neutral.
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8.  The mass number (A), also called atomic
mass number or nucleon number, is the total
number of protons and neutrons (together
known as nucleons) in an atomic nucleus
 the difference between the mass number and
the atomic number gives the number of
neutrons (N) in a given nucleus: N=A−Z.
 11Na23
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9.  Isotopes: The atoms having same atomic number
but different atomic mass number are
called Isotope.eg.
 1H1
1H2
1H3
Hyrogen Duterium Tritium
 Isobars: Nuclides having the same mass number
but having the different Atomic number are called
Isobar.eg.
 92U234
90Pa234
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11.  He2 2
 Ne10 2 8
 Ar18 2 8 8
 Kr36 2 8 18 8
 Xe54 2 8 18 18 8
 Rn86 2 8 18 32 18 8
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12.  All the Inert gas elements has eight electrons
in the outer most orbit.
 They all have completed octet
 They do not donate or share electrons and
chemically react
 They are highly stable so they remain inert.
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13.  All the elements try attain the inert gas
configuration by sharing or donating or
accepting electrons by reacting and try to
complete its octet or more simply
 The tendency of an atom to have eight
electrons in the outer most orbit
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14.  Chemical bond can be defined as :
" the force of attraction between two
atoms or ions that hold them
together in a unit is called
Chemical Bond".
Actually chemical bond is the main factor that
makes molecules and compounds. By the
interaction
of outer electrons, great forces of attraction
are developed between two atoms. This force of
attraction is called chemical bond.
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15.  There are three types of chemical bonds:
Ionic bond or Electrovalent bond
Covalent bond
Coordinate Covalent bond
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16.  Chemical bond formed between two atoms due to
transfer of electron(s) from one atom to the other
atom is called "Ionic bond" or "electrovalent bond".
 In ionic bond formation one atom looses electron(s)
and the other picks it up. The atom that looses
the electron acquires positive charge and the other
atom which gains the electron becomes a
negatively charged particle. Due to opposite charge
an electrostatic force of attraction is setup between
them.
This force hold these atoms together in a unit.
This force of attraction is referred to as
"IONIC BOND".
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17.  Electronic arrangement of
 Na (Z=11) is K = 2 , L = 8, M = 1
Electronic configuration of Na is 1s2, 2s2, 2p6, 3s1
It has one valence electron., Na-atom loses its
valence electron
 Electronic arrangement after losing an electron is
 K = 2, L = 8 , M = 0
Electronic configuration after losing an electron is
 1s2, 2s2, 2p6 .This shows that its octet is complete.
 Due to loss of one electron Na becomes Na+ -ion.
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18.  Electronic arrangement of
 Cl (Z=17) is K = 2, L = 8, M = 7
Electronic configuration of
 Cl is 1s2, 2s2, 2p6, 3s2 3p5.
Cl-atom needs one electron to complete its
octet.
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19.  Electronic arrangement after acquiring an
electron
 : K = 2, L = 8, M = 8
Electronic configuration of Cl is 1s2, 2s2, 2p6,
3s2, 3p6 .
 Chlorine atom is now converted into Cl-_ion. We
know that positive and negative ions attract each
other, therefore an electrostatic force
of attraction is set up between Na+ & Cl- ions.
This force unites these ions in a unit. In this way
ionic bond is formed between Na and Cl atoms
which results in the formation of sodium
chloride.
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20.  A covalent bond, also called a
molecular bond, is a chemicalbond that
involves the sharing of electron pairs between
atoms. These electron pairs are known as
shared pairs or bonding pairs, and the stable
balance of attractive and repulsive forces
between atoms, when they share electrons, is
known as covalent bonding.
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23.  What is an Ammonia Molecule?
 Nitrogen and hydrogen are both non-metals.
A nitrogen atom has 5 electrons in its outer
shell.
Nitrogen is in group 5 of the periodic table.
A hydrogen atom has 1 electron in its outer
shell.
Hydrogen can only form 1 bond.
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24.  Three hydrogen atoms each share their 1
electron with
nitrogen to form three covalent bonds
and make an ammonia molecule (NH3).
 This is a picture of an ammonia molecule.
 By sharing the two electrons where the shells touch
each hydrogen atom can count 2 electrons in
its outer shell
and the nitrogen atom can count 8 electrons in
its outer shell.
These full outer shells with their shared electrons
are now stable, and the NH3 molecule will
not react further with other hydrogen or nitrogen
atoms.
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26.  1. What are the types of bonding?
 2. Define ionic bond.
 3. Define covalent bond
 4. what is meant by isotope? Give example
 5.What is meant by isobar? Give example
 6.Define atomic number.
 7. Define mass number.
 8. Mention charge and mass of sub atomic
particles.
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27.  1. What isArrhenius theory of acids and bases?
 2. What is Lowry- Bronsted theory of acids and
bases?
 3. What is Lewis theory of acids and bases?
 4. Define pH?
 5. Define pOH?
 6. What is ionic product of water?
 7. What is an Indicator?
 8. What is a Buffer solution?
 9. Give any two examples for indicators?
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28.  1.Define molecular mass of a substance.
 2. Define mole
 3. What is molecular formula?
 4. StateAvogadro's hypothesis.
 5. What is known as vapour density?
 6. DefineAvogadro's number.
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29.  1.State octet rule
 2. How do ions are formed?
 3.Write a note on indicators
 4. what is meant by a buffer? Give example.
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30.  1.Explain electrovalent bond with an example.
 2. Explain covalent bond with an example.
 3. Explain the Lowry- Bronsted theory of acids
and bases with a suitable example.
 4. Explain the Lewis concept of acids and bases
with examples.Mention its advantages also.
 5.Write a note on applications of pH in industries
 6. Derive the relationship between vapour density
and molecular mass.
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