Asthram -1
ABCD……………… of CHEMISTRY
Presented to: Bhavishya
Phase: II
Concept and material by
Y.Vijay Aryan
SIIT JEE
9948925181
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Start your chemistry Game !
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ABCD……. Of Chemistry:
Most of the Universe consists of matter and energy. Energy is the capacity to
do work. Matter has mass and occupies space. All matter is composed of basic
elements that cannot be broken down to substances with different chemical or
physical properties. Elements are substances consisting of one type of atom,
for example Carbon atoms make up diamond, and also graphite. Pure (24K)
gold is composed of only one type of atom, gold atoms. Atoms are the smallest
particle into which an element can be divided. The ancient Greek philosophers
developed the concept of the atom, although they considered it the
fundamental particle that could not be broken down. Since the work of Enrico
Fermi and his colleagues, we now know that the atom is divisible, often
releasing tremendous energies as in nuclear explosions or (in a controlled
fashion in) thermonuclear power plants.
Symbols of the elements:
Part of the language of chemistry are the names and symbols of the chemical
elements. There are 91 naturally occurring elements found on Earth. Once you
are familiar with the names and symbols of the more common elements, you
will be able to learn to write chemical formulas and to do some simple chemical
calculations.
Definition of an element : A substance that cannot be broken down by any
chemical means. Elements are defined by the number of protons they possess.
Examples: gold, iron, silver
1. A BRIEF HISTORY OF ELEMENT SYMBOLS
The modern symbols used to represent the chemical elements consist of one or
two letters from the element's name. Historically, symbols were not always like
this.
Some of the earliest symbols were those used by the ancient Greeks to
represent the four elements earth, air, fire, and water. These were adopted by
Plato, using the Pathagorean geometric solids:
Earth
Air
Fire
Water
cubic atoms
octahedral atoms tetrahedral atoms icosahedral atoms
As other chemical substances were defined, symbols of the planets were used.
Ancient symbols:
Gold The symbol for
gold could also be used
to represent the sun in
astrology.
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Iron The symbol for
iron could also be used
to represent the planet
Mars
in
astrology.
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Lead The symbol for
lead was also used to
represent the planet
Saturn in astrology.
Mercury,
called
quicksilver The symbol
for mercury could also
be used to represent
the planet of the same
name in astrology.
MagnesiumAlchemists
used
'Magnesia
alba'
(literally
"white
magnesia") which was
magnesium carbonate
(MgCO3), also known as 'mild
magnesian earth.'
PhosphorusAlchemists often used
light as a symbol of the
spirit, therefore they
were
especially
interested in light that
seemed to be trapped in matter
such as phosphorus.
Platinum-chemists
believed platinum to be
an amalgamation of
gold and silver.
Potash
carbonate)
Silver : The symbol for
silver is also associated
wth
the
moon
in
astrology.
Sulfur is one of the
three
heavenly
substances
(sulfur,
mercury & salt). It was
widely
used
in
chemical pratice.
Tin: The symbol for tin
could also be used to
represent the planet
Jupiter in astrology.
(potassium
Zinc-Philosophers'
wool, or nix alba (white
snow) was zinc oxide
made by burning zinc
in air.
John Dalton, in advocating his
atomic
theory
recommended
symbols composed of circles.
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JOHN DALTON'S NOTATION
symbols:
of
Before the early 1800s the symbols used to denote chemical elements and
compounds were obscure. Alchemists wanted to keep their work secret and so
devised symbols for the chemicals they used that would not reveal anything
about them. This all changed with the work of Jöns Jakob Berzelius.
Scientists of the day, however, viewed Dalton’s symbols as cumbersome and
with little improvement, Finally, in 1813, Jon Jakob Berzelius devised a system
using letters of the alphabet. He argued that letters should be used because
they could be written more easily than other signs.
The modernized version of Berzelius' system follows under the heading:
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System for Determining Symbols of the Elements
1. The symbols of the most common elements, mainly nonmetals, use the first
letter of their English name.
Examples: H, B, C, N, O, F, P, S, I
2. If the name of the element has the same initial letter as another element,
then the symbol uses the first and second letters of their English name.
Examples: He, Li, Be, Ne, Al
3. If the first two letters of the element name are the same as another element,
then the symbol consists of the first letter and the first consonant of the
English name that they do not have in common.
Examples: magnesium has the symbol Mg (first letter and first consonant)
manganese has the symbol Mn
chlorine has the symbol Cl(first letter and first consonant NOT in
common)
chromium has the symbol Cr
4. Some symbols are based on the old name or Latin name of the element.
Na(Sodium)
Natrium
Sb(Antimony)
Stibium
Fe(Iron)
Ferrum
W(Tungsten)
Wolfram
Cu(Copper)
Cuprum
Au(Gold)
Aurum
Ag(Siver)
Argentums
Hg(Mercury)
Hydrargyrum
Sn(Tin)
Stannum
Pb(lead)
Plumbum
5. New elements, or those with disputed claims for discovery/ synthesis are
named using three letters based on the Latin for their atomic numbers:
These symbols can be used for elements from atomic number 100
The names are derived by using root words for the three digits in the atomic
number of the element and adding the suffix –ium
Number
0
1
2
3
4
5
6
7
8
9
Rootword nil
Un
bi
tri
quad pent hex
sept oct
enn
In certain cases the names are shortened.
a. bi + ium = bium
b. tri + ium = trium
c. enn + nil = ennil
Example: Write the IUPAC name of an element with atomic number 108
Answer: Un-nil-oct-ium = Unniloctium
Symbol: Uno
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2. MODERN CHEMICAL SYMBOLS
Listed below are the atomic numbers, names, and symbols of the most
common elements. The atomic number is used to determine the place of the
element in the periodic table, it also has other meaning as you will find out
later in the course.
Become familiar with the names and symbols of these elements.
Atomic
Atomic
Number
Name
Symbol
1
Hydrogen
H
2
Helium
He
3
Lithium
Li
4
Beryllium
Be
5
Boron
B
6
Carbon
C
7
Nitrogen
N
8
Oxygen
O
9
Fluorine
F
10
Neon
Ne
In the beginning:
Not until around 460 B.C., did a Greek philosopher, Democritus, develop the
idea of atoms. He asked this question: If you break a piece of matter in half,
and then break it in half again, how many breaks will you have to make before
you can break it no further? Democritus thought that it ended at some point, a
smallest possible bit of matter. He called these basic matter particles, atoms.
For example consider an element carbon, start dividing it into fine particles
and reach the stage where carbon particles cannot be further broken down.
Moreover, if carbon has to undergo any chemical change, then the change
must start from this
particle.This smallest
particle of carbon is
called an atom of
carbon.
The word "atom"
comes from the greek
"a-tomos" and
signifies
"indivisible". This
notion was invented
by Leucippe of Milet
in 420 B.C.
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But advanced science confirmed that atom is also indivisible.
What does an atom constitutes ?
ATOMIC PARTICLES:
Atoms consist of three subatomic particles:
 electrons are negatively charged particles and their properties are
summarized in the following table
 protons are positively charged particles and their properties are
summarized in the following table
 neutrons have no charge and their properties are summarized in the
following table
Particle
Mass (kg)
Mass (amu)#
Charge*
Electron
9.10939 x 10
-31
0.00055
-1
Proton
1.67262 x 10
-27
1.00728
+1
Neutron
1.67493 x 10
-27
1.00866
0
1 amu (atomic mass unit) = 1.66054 x 10
* unit charge = 1.602 x 10 -19 C (coulomb)
#
-27
kg
ELECTRONS:
 J.J. Thomson determined mass of the electron, e-, in 1897
o the mass is 5.486 x 10 -4 amu or 9.10939 x 10 -31 kg
 Robert Millikan measured the charge of e-, -1.602 × 10-19 coulombs
 Thomson developed the "plum pudding" model of the atom.
This model had all atomic particles distributed evenly throughout the
volume of the atom
 Rutherford developed the "nuclear" model of the atom
o based upon his experiment he showed that atoms contains regions of
highly dense, positive material, called the nucleus
o the nucleus is very dense, 99.95% (or more) of the mass of the atom is in
the nucleus which has a diameter of approximately 10 -15 m
o Rutherford discovered this through his famous experiment with gold foil
in which he shot alpha particles (fairly massive particles with a positive
charge) through thin gold foil and found that many particles were
strongly deflected and some bounced back at him! This could only
happen if the gold foil atoms contained massive centers that had a
positive charge, as exhibited in the figure below.
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PROTONS:
 small, positively charged particles (+1.602 × 10-19 coulombs
 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
NEUTRONS:
 small particles with no charge
 reside in the nucleus
 along with the proton, make up most of the mass of the atom
 a differing number of neutrons is what defines an "isotope" of an atom
ATOMIC NUMBER: The atomic number corresponds to the number of protons
in the nucleus of an atom of that element. It also corresponds to the number of
electrons in the neutral atom.
 the atomic number has the symbol, Z, and is shown as a subscript to the
element symbol
 the atomic number gives the number of protons in the nucleus (and the
number of electrons if the species is neutral) of a particular atom
 the atomic number defines a specific type of atom since each different
type of atom (representing each element) will have a different number of
protons in the nucleus
MASS NUMBER:
 the mass number has the symbol, A, and is shown as a superscript to
the element symbol
 the mass number gives the mass of atom in amu, atomic mass number,
and is approximately equal to the number of protons plus the number of
neutrons
ELEMENTAL SYMBOLS:
AXZ
Elemental symbols are typically written as above where X is the element
symbol with the mass number as a superscript and the atomic number as a
subscript.
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ISOTOPES:
 Almost all atoms have "Isotopes"
 Elements with the same number of protons (atomic number) but differing
number of neutrons – isotopes are the same elements (atoms) with
different masses
 isotopes will have slightly different chemical and physical properties due
to the difference in mass, which can be very helpful in characterizing
substances
 for example, below are three isotope of carbon, C:
12C6
13C6
14C6
#p
6
6
6
#e
6
6
6
#n
6
7
8
notice that the sum of # protons and # neutrons is equal to the
mass number
 because nearly all elements have one or more isotopes, the mass of a
naturally occurring element will be a "weighted average" of all the
isotopes
which
occur
naturally,
for
example:
Carbon has two prominent isotopes which occur naturally (C-14 is
present in very small quantities and is radioactive so does not stick
around long and we won't count it here) shown below with their relative
percent abundance
C-12 12.0000 amu 98.9% abundant
C-13 13.0000 amu 1.1 % abundant
To determine the mass of naturally occurring carbon, we calculate the
weighted average of the two isotopes by summing (fractional
abundance)(mass of isotope) for each isotope:
mass C = (0.989)(12.0000) + (0.011)(13.0000) = 12.011 amu
Atomic weight:
Atoms and molecules are material particles and they possess mass. The mass
of one atom of an element is known as the atomic weight of the element.
Atomic weight should not be confused with another concept called atomic
number of an element. Atomic number A is the simple sum of the number of
protons (Z) and neutrons (N) the element has. Thus A = Z + N and is an integral
number as Z and N both are integer numbers. The atomic mass or weight is
an actual measure of the weight of the atoms in grams or kilograms.
The table below gives mass of some of the atoms.
Element
Mass in Kg
Hydrogen
1.67 x 10-27 kg
Oxygen
26.56 x 10-27 kg
Chlorine
58.9 x 10-27 kg
Uranium
395.0 x 10-27 kg
We can see that when we deal with the masses, since they are very small, it is
inconvenient to use such numbers in calculations. To make calculations less
o
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cumbersome, weight of the atom of an element is compared to the weight of
standard atom and their ratio is taken.
In 1962, it was decided by the international community, mass of the isotope of
carbon, namely 12C, should be taken as 12. All the other atomic weights are
compared to the weight of an atom of 12C.
Average weight of
one atom of the element
Atomic weight of an atom of an element
=
1/12 x weight of one atom of
12C
Average weight of one atom of the element
Atomic weight of
an atom of an element
=
x 12
weight of one atom of
12C
How
to
calculate
the
average
weight
of
an
element
Elements exist in various isotopes. The average weight of an element is
calculated from the proportion in which the isotopes occur (relative
abundance).
For example the atom chlorine has two isotopes : 35Cl and 37Cl. Their relative
abundance is in the ratio of 3 : 1.
3 x 35 + 1 x 37
Thus the average weight of Cl atom =
= 35.5
4
Please note that atomic weight is a ratio, hence does not have any units
associated with it.
If an element does not have an isotope, then its average weight is same as that
of its atomic number. Gold (Au) and Platinum (Pt) fall in this category.
The table below gives some of the atomic weights of elements accepted
internationally.
Element
Symbol
Atomic Weight
Hydrogen
H
1.008
Helium
He
4.003
Lithium
Li
6.939
Carbon
C
12.011
Oxygen
O
15.994
Sodium
Na
22.990
Silicon
Si
28.090
Chlorine
Cl
35.452
Gram atomic weight or gram atomic mass : In chemical reactions, we deal with
normal mass units such as grams (and kilograms). The quantity of element
equivalent to its atomic weight taken in grams is called the gram atomic weight
(GAW) or gram atomic mass (GAM). For example : 1 gram atomic mass of
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sodium will be equal to 22.99 gm. Similarly 1 gram atomic mass of carbon will
be equal to 12.011 gm.
Atomic
Number
Name
Symbol
Standard
atomic weight
Group
Period
1
Hydrogen
H
1.00794
1
1
2
Helium
He
4.002602
18
1
3
Lithium
Li
6.941
1
2
4
Beryllium
Be
9.012182
2
2
5
Boron
B
10.811
13
2
6
Carbon
C
12.0107
14
2
7
Nitrogen
N
14.0067
15
2
8
Oxygen
O
15.9994
16
2
9
Fluorine
F
18.9984032
17
2
10
Neon
Ne
20.1797
18
2
11
Sodium (Natrium)
Na
22.98976928
1
3
12
Magnesium
Mg
24.3050
2
3
13
Aluminium (Aluminum)
Al
26.9815386
13
3
14
Silicon
Si
28.0855
14
3
15
Phosphorus
P
30.973762
15
3
16
Sulfur
S
32.065
16
3
17
Chlorine
Cl
35.453
17
3
18
Argon
Ar
39.948
18
3
19
Potassium (Kalium)
K
39.0983
1
4
20
Calcium
Ca
40.078
2
4
21
Scandium
Sc
44.955912
3
4
22
Titanium
Ti
47.867
4
4
23
Vanadium
V
50.9415
5
4
24
Chromium
Cr
51.9961
6
4
25
Manganese
Mn
54.938045
7
4
26
Iron (Ferrum)
Fe
55.845
8
4
27
Cobalt
Co
58.933195
9
4
28
Nickel
Ni
58.6934
10
4
29
Copper (Cuprum)
Cu
63.546
11
4
30
Zinc
Zn
65.38
12
4
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Molecular weight: It is referred with respect to molecules.
Average weight of one molecule of the substance
Molecular weight of =
x 12
a substance
weight of one atom of 12C
Types of ions:
classification
classification
II
I
Based on
charge
Electro positive ions
ex: k+, Ag+, Na+
Based on types
of atoms
involved
Simple ions
ex: k+, Ag+, Cl-,O2-
Electro negative ions
Compound ions
ex: Cl-,O2-,SO42-
ex: SO42- SO32-
Ions and radicals:
Atom is electrically neutral. But if it is stripped of electrons it gets a
positive charge. This is because there is an imbalance of positive and
negative charges. Similarly if an atom attracts extra electrons, it becomes
negatively charged. The charged atoms are called ions.
Na
(neutral sodium atom)
Cl
(neutral chlorine atom)
Na +
(positive sodium ion)
+
e(electron)
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+
e(electron)
Cl(negative chlorine ion)
13
What is a Radical?
Sometimes in a chemical reaction of compounds the constituent elements are
not released, but there may be a group of atoms sticking together. These
groups are called radicals. Thus a radical is a component of a compound
consisting of groups of atoms. Radicals can be positively as well as negatively
charged. To simplify the jargons, ions are called simple radicals and groups of
atomic radicals are called compound radicals. For example (OH) is called a
radical and is negatively charged. Hence it is written as (OH)-, Other common
compound radicals are (SO4)2-, (NO3)-, etc.
Some radicals and their chemical symbols are listed below:
Valency
Radical/ Ion
Formulae
Chloride, Bromide, Iodide
Monovalent [1]
Cl-, Br-,I-
Hypochlorite
ClO1-
Chlorite
ClO21-
Chlorate
ClO31-
Perchlorate
ClO41-
Hypobromite
BrO1-
Bromite
BrO21-
Bromate
BrO31-
Perbromate
BrO41-
Hypoiodite
IO1-
Iodite
IO21-
Iodate
IO31-
Periodate
IO41-
Hydroxide
OH1-
Nitrite
NO21-
Nitrate
NO31-
Bicarbonate [Hydrogen carbonate] HCO31Bisulphite [Hydrogen sulphite]
HSO31-
Bisulphate [Hydrogen sulphate]
HSO41-
Dihydrogen phosphate
H2PO41-
Cyanide
CN1-
Cyanate
CNO1-
Thiocyanate
SCN1-
Permanganate
Acetate
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MnO41CH3COO114
Divalent [2]
Formate
HCOO1-
Hydride
H1-
Hydrogen
H+
Lithium
Li+
Sodium
Na+
Potassium
K+
Ammonium
NH4+
Cuprous
Cu+
Argentous
Ag+
Mercurous
Hg+
Aurous
Au+
Oxide
O2-
Peroxide
O22-
Carbonate
CO32-
Sulphite
SO32-
Sulphate
SO42-
Thiosulphate
S2O32-
Biphosphate [Hydrogen phosphate] HPO42Chromate
CrO42-
Dichromate
Cr2O72-
Oxalate
C2O42-
Manganate
MnO42-
Beryllium
Be2+
Magnesium
Mg2+
Calcium
Ca2+
Barium
Ba2+
Nickel
Ni2+
Zinc
Zn2+
Cobalt
Co2+
Cupric
Cu2+
Argentic
Ag2+
Mercuric
Hg2+
Ferrous
Fe2+
Plumbous
Pb2+
Stannous
Sn2+
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Trivalent [3]
Tetravalent[4]
Pentavalent[5]
Mangannous
Mn2+
Phosphite
PO33-
Phosphate
PO43-
Phosphide
P3-
Boride
B3-
Borate
BO33-
Nitride
N3-
Aluminate
AlO33-
Aluminium
Al3+
Chromium
Cr3+
Boron
B3+
Ferric
Fe3+
Auric
Au3+
Antimonous
Sb3+
Cobaltic
Co3+
Carbide
C4-
Plumbic
Pb4+
Stannic
Sn4+
Platinic
pt4+
Manganic
Mn4+
Arsenic
As5+
Antimonic
Sb5+
How to write a Chemical formula ?
Alphabets formed millions of words in English language, Just like that
elements combine to form millions of compounds. The combinations of
elements can be best understood by Criss cross method.
The Criss Cross Method is used to find the general formula for ionic
compounds.
For monatomic ions, you simply take the absolute value of the ionic charge for
the positively charge ion and make it the subscript for the negatively charged
ion and vice versa.
Example: Al +3 and Cl -1 The 3 becomes the subscript for the chloride ion and
the 1 becomes understood for aluminum, to form aluminum chloride: AlCl3
Ionic compounds that form from polyatomic ions can also make use of the criss
cross method. The only additional step is to include parenthesis around the
polyatomic ion if it has a subscript other than one.
Example: Mg+2 and OH-1 The 2 becomes the subscript for the hydroxide ion,
but a set of parenthesis is needed to indicate 2 of each the O and the H. The 1
becomes the understood subscript for Mg. Magnesium Hydroxide: Mg(OH)2
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Writing formula from name: e.g. nickel (III) nitrate
Step 1: Write the ionic symbol of the cation and anion.
Ni3+ NO3(For cations with more than one charge, the charge will be given as a roman
numeral.)
Step 2: Use the “criss-cross” method to determine the subscripts of each of the
ion in the formula. Ni (1) NO3 (3)
(The criss-cross method helps one find the least common multiple of the
charges. An ionic compound formula is the least whole number ratio of ions in
which the total positive charge equals the total negative charge of the cations
and anions respectively.)
Step 3: Write the empirical formula (least whole number ratio of ions of the
compound). Ni(NO3)3
(Parentheses are used around polyatomic ions when more than one of the ion
is required in the formula.
Write the formulas for the following ionic compounds:
a) Silver sulphide
b) Tin(IV) sulphate
c)Potassium permanganate
d)Titanium (IV) oxide
e) Aluminum chloride f) Indium selenide
Writing the name of a ionic compound from the formula: e.g. Fe2(CO3)3
Step 1: Name the cation. “iron (III)”
(For cations with more than one charge, the charge needs to be included as a
roman numeral. The charge is deduced from the subscripts of the ions in the
empirical formula, i.e. the reverse “criss-cross” method.)
Step 2: Name the anion. “carbonate”
(Polyatomic ions have names that the student has memorized. Monoatomic
anions end with the “-IDE” suffix.)
Step 3: Put the two names together: “iron (III) carbonate”
Name the following compounds:
a) Ba(ClO)2 b) KBr c) ZnSO4 d) NH4Cl
e) AuCl3
f) Hg2S g) Li3PO3
Covalent (or molecular) Compounds (binary only)
Writing formulas from names: e.g. dinitrogen monoxide
Step 1: Write the elemental symbols of the two elements: N O
Step 2: Make the greek prefix the element’s subscript N2O
(Subscripts of “1” are never written.)
 Write the formulas of the following molecular compound names:
a) Phosphorus pentabromide b) Silicon tetrafluoride c) Dicarbon disulfide
d) Nitrogen triiodide
e)Sulfur hexafluoride f) Tetraarsenic decaoxide
Writing names from molecular formulas: e.g. CS2
Step 1: Write the name of the first element as on the periodic table.
“carbon”
Step 2: Add a Greek prefix to this name if there is more than one of the element
in the compound.
Step 3: Write the name of the second element ending with the “-IDE”
suffix. Always add a Greek prefix to indicate the number of the second
element.
 Write the names of the following molecules:
a)NO2
b)N2O4
c)P2S5
d)BF3
e)P4O10
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Chemical formulae of some important compounds:
COMMON NAME
King of chemicals
Washing soda
Baking soda
Soda ash
Aquafortis
Bleaching powder
Brine solution
Rock salt
Bone ash
Caustic soda
Lime stone
Dry ice
Grain alcohol
Inorganic graphite
Inorganic Benzene
Laughing gas
Tear gas
Quick Lime
Slaked Lime
Urea
Carbinol
Plaster of paris
Soda lime
Quick silver
Nitre
Oleum
Water gas
Marsh gas
Gypsum
Aqua regia
Nitration mixture
Epsom salt
Hematite or magnetite
Blue vitriol
CHEMICAL NAME
Sulphuric acid
Hydrated sodium
carbonate
sodium bicarbonate
Anhydrous sodium
carbonate
Nitric acid
Calcium oxychloride
Sodium chloride(sol)
Sodium chloride
Calcium phosphate
Sodium hydroxide
Calcium carbonate
Solid carbondioxide
Ethanol
Boron nitride
Borozole
Nitrous oxide
Chloropicrin
Calcium oxide
Calcium hydroxide
Amino methanamide
Methanol
Calcium sulphate hemi
hydrate
---------Mercury
Potasium Nitrate
Fuming sulphuric acid
Water gas
Methane
Calcium sulphate di
hydrate
----------------------Magnesium hepta
hydrate
Ferroso ferric oxide
Copper sulphate penta
hydrate
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FORMULA
H2SO4
Na2SO4.10H2O
NaHCO3
Na2CO3
HNO3
CaOCl2
NaCl(sol)
NaCl
Ca3(PO4) 2
NaOH
CaCO3
CO2
C2H5OH
BN
B3N3H3
N2O
CCl 3NO2
CaO
Ca(OH)2
NH2CONH2
CH3OH
CaSO4.½ H 2O
CaO + NaOH
Hg
KNO3
H2S2O7
CO + H2
CH4
CaSO4.2 H 2O
HNO3 + HCl
HNO3 + H2SO4
MgSO4.7H2O
Fe3O4
CuSO4.5H2O
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Assignment -I:
1. Identify the elements from the following words:
a. ArGeNTiNa
b. CoRn
c. LiON
d. CabbaGe
2. Find the number of protons, electrons and neutrons in a. Al b. Mg c. Zn
3. Find the number of protons, electrons and neutrons in a. Al3+ b. Na+ c. Cl4. An atom contains 8 protons & 8 neutrons in the nucleus there are 10
electrons. The atom is _____________
(a) Neutral & Metal
(b) Neutral & An Ion
(c) Neutral & Nonmetal
(d) An Ion & Nonmetal (e) An Ion & Metal
5. A sodium atom has 1 electron in its outer shell which can hold 8 electrons.
to
achieve
stability,
the
sodium
atom
_________
(a) Gives up 1 electron to another atom
(b) Adds 7 electrons
(c) Adds 4 electrons
(d) Adds 2 electrons
(e) Adds 3 electrons
6. Why an atomic number does not change, during a chemical reaction ?
7. Two neutrons are added to the nucleus of Carbon. Name the new particle
that forms and also write its atomic number.
8. Find the neutron/ proton ratio of Zinc and carbon.
9. A neutral atom consists of 19 protons and 20 neutrons. Find the number of
electrons in it.
10. Find the number of smallest units of masses that make 1 CGS unit of mass
11. Find the atomic weight of one Scandium atom.
12. Find the molecular weight of the following molecules:
a. Sulphuric acid
b. Nitric acid
c. Epsom salt
d. CO2
13. There is a compound containing C, H and O. The amount of ‘C’ present is
36 amu and the amount of ‘H’ present is 8 amu. Oxygen contributes a
mass of 16 ×1.66 × 10-24 g. Find the molecular formula and the molecular
weight of the compound.
14. Find the gram molecular weight of Calcium carbonate.
15. Find the weight of 50 Sulphuric acid molecules.
16. All radicals are ions, but all ions are not radicals. Explain it ?
17. Write the formulae and valencies of the following ions:
a. Sulphate
b. Sulphite
c. Nitrate
d. Carbonate
e. Manganate
f. ferric
g. Stannous
h. Chlorite
18. Write the formulae of the following compounds by criss cross method.
a. Aluminium Sulphate
b. Chromium Sulphate
c. Silicon Carbide
d. Boron nitride
e. Magnesium bicarbonate
19. Nitration mixture is a mixture of _____________ and _____________
20. Chemical formula of washing soda is _____________
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19
Assignment – II:
1. Among the following, select the symbols whose names are named after the
scientists and write their names.
C, No, Fm, K, Ag, Cm, Md, N, Es, Fe
2. Identify the names of the elements with which they are made :
a. BeCaUSe b. SHOLaY c. CArBON d. SKY
3. Give two examples each for elements which have dependent and
independent existence of atoms.
4. Calculate the number of protons, electrons, neutrons in the isotopes of
hydrogen.
5. Calculate the number of protons, electrons, neutrons present in O2-,Cl-, K+
ions.
6. Why the atomic number of an element does not change during a reaction.
7. The mass number of a neutral element is 65, the number of negatively
charged particles in it are 30.Then find the number of neutrally charged
particles in it and write the name of the element.
8. The ratio of the number of neutrons present in Scandium and Chromium.
9. Find the number of the smallest units of masses that make 1 MKS unit of
mass
10. There is a compound containing C, H, O. The amount of C present is 72
amu and the amount of H present is 12amu. Oxygen contributes a mass of
96 × 1.66 × 10-24 g. Find the molecular weight of the compound.
11. Find the molecular weight of 200 H2SO4 molecules.
12. A compound consists of Nitrogen and Oxygen. Nitrogen atom contributes
28 amu of mass, whereas Oxygen atom contributes 60 amu. Find the
molecular formula and the molecular weight of the compound.
13. Write the formulae for the following compound using criss cross method.
a. Sodium bicarbonate
b. Ferric hydroxide
c. limestone
14. Balance the equation in which Nitrogen dioxide, on treating with water,
gives rise to Nitrous acid and Nitric acid
15. The 100th element, Fermium is based on a scientist’s name. Name the
scientist , the symbol of element and write its IUPAC name.
16. Which elements exhibit highest valency in the periodic table ?
Choose the correct answer
1. The weight of one calcium atom is
a. 40
b. 20 c. 40 amu d. 40 gm
2. Size of the nucleus is ______ times the size of atom
a. 105 b. 103 c. 10-5
d. 10-3
3. Homogeneous molecules are also called as __________ molecules.
a. Compound b. Elementary
c. Single
d. double
4. Atomicity of Carbon in C60 is
a. 6
b. 12
c. 60
d. 24
5. Molecular weight of Calcium carbonate is ________
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20
a. 59
b. 159
c. 100
d. 112
6. Molecular weight of Soda ash is
a. 106
b. 108
c. 112
d. 116
7. Valency of N in N2O is
a. 2
b. 1
c. 3
d. 4
8. Valency of Sulphur in SF2, SF6, SF4 is
a. 2, 3, 5
b. 2, 4, 6
c. 2, 6, 4
d. 1, 2, 5
9. Identify the element that forms an electro negative ion.
a. He
b. H
c. S
d. CO3
10. Identify the element with highest valency among the following :
a. Carbon
b. Ruthenium
c. Aluminium
d. Arsenic
11. Identify the formula of Aluminium nitride.
a. AlN
b. Al2N
c. Al3N
d. Al3N2
12. Charge of Zincate radical is
a. ZnO–
b. Zn2O–
c. ZnO22–
d. ZnO3–
13. Identify the formula of Carbon tetra chloride.
a. CCl
b. CCl4
c. C4Cl
d. CCl2
14. Identify the formula of Stannic chloride.
a. SnCl
b. SnCl2
c. SnCl3
d. SnCl4
15. Identify the formula of Potassium dichromate.
a. K2CrO7
b. K2Cr2O7
c. K1Cr3O7
d. KCrO7
16. Charge of Manganate ion is
a. MnO4–
b. MnO2–
c. Mn2O4–
d. MnO42–
17. Identify the formula of Sodium thiosulphate.
a. Na1S2O3
b. Na2S2O3
c. Na3S2O3
d. Na1S3O3
1.
2.
3.
4.
5.
Chloride
Hypo chlorite
Chlorate
Chlorite
Per chlorate
Matching
(
)
(
)
(
)
(
)
(
)
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a. ClO–
b. ClO2–
c. ClO3–
d. Cl3–
e. ClO4–
f. Cl–
21