New Words

ATOMICITY— the number of atoms present in a molecule of an element 

VALENCY- a measure of the combining capacity of an element or radical 

Words derived from greek, latin etc

The word 'stoichiometry' is derived from 2 Greek words - stoicheion (meaning element) and metron (meaning measure). Stoichiometry, thus, deals with the calution of mases (sometimes volumes also)

Important Formulas in science

Si unit of density =	SI unit of mass ------------------- SI unit of volume	kg∕m³ (or) kg m⁻³
Temperature	1. ℉ = 9∕5 (℃) +32 Kelvin scale is related to celsius scale 2. K = ℃ + 273.15
Mass per cent =	Mass of solute -----------------        ✖100 Mass of solution
Molarity (M) =	No.of moles of solute ---------------------------- Volume of solution in litres
Molality (m) =	No.of moles of solute ---------------------------- Mass of solvent in kg

Definitions of SI Base Units in 11th class chemistry

Unit of length	metre	The metre is the length of the path travelled by light in vacuum during a time interval of 1/299 792 458 of a second.
Unit of mass	kilogram	The kilogram is the unit of mass; it is equal to the mass of the international prototype of the kilogram.
Unit of time	second	The second is the duration of 1 192 631 770 periods of the radiation corresponding to the transition between the two hyperfine levels of the ground state of the caesium - 133 atom.
Unit of electric current	ampere	The ampere is that constant current which, if maintained in two straight parallel conductors of infinite length, of negligible circular cross-section, and placed 1 metre apart in vacuum, would produce between these conductors a force equal to 2 ✖ 10⁻⁷ newton per metre of length.
Unit of  thermodynamic temperature	kelvin	The kelvin, unit of thermodynamic temperature, is the fraction 1/273.16 of the thermodynamic temperature of the triple point of water.
Unit of amount of substance	mole	1. The mole is the amount of  substance of a system which contains as many elementary entities as there are atoms in 0.012 kilogram of carbon-12; its symbol is "mol." 2. When the mole is used, the elementary entities  must be specified and may be atoms, molecules, ions, electrons, other particles, or specified of such particles.
Unit of  luminous intensity	candela	The candela is the luminous intnsity, in a given direction, of a source that emits monochromatic radiation of frequency 540 ✖ 10¹² hertz and that has a radiant intensity in that direction of 1/683 watt per steradian.

Full form in Chemistry terms

Abbreviation	Compound name
AZT	Azidothymidine
CFCs	Chlorofluorocarbons
Ac	Acetyl Group
acac	Acetylacetone
ADP	Adenosine diphosphate
AIBN	Azobisisobutyronitrile
AMP	Adenosine monophosphate
Ar	Aryl
ATP	Adenosine triphosphate
9-BBN	9-Borabicyclo(3.3.1)nonane
9-BBN-H	9-borabicyclo[3.3.1]nonane
Bn, Bz	benzoyl
BOC, Boc	Di-tert-butyl dicarbonate
BODIPY	boron-dipyrromethene
bpy	2,2′-Bipyridine
Bu, n-Bu	n-butyl
s-Bu	sec-butyl
t-Bu	tert-butyl
Bz	benzoyl
cAMP	3',5'-cyclic adenosine monophosphate
CAN	Ceric ammonium nitrate
CBZ, Cbz	benzyloxycarbonyl
COD	1,5-Cyclooctadiene
COT	1,3,5,7-Cyclooctatetraene
Cp	cyclopentadienyl
mCPBA	meta-Chloroperoxybenzoic acid
Cy	cyclohexyl
DABCO	1,4-diazabicyclo[2.2. 2]octane
dansyl	5-(DimethylAmino)Naphthalene-1-SulfonYL chloride
DBN	1,5-Diazabicyclo[4.3. 0]non-5-ene
DBU	1,8-diazabicyclo[5.4.0]undec-7-ene
DCC	N,N'-dicyclohexylcarbodiimide
CGPM	Conference Generale des Poidset Measures.
NMI	National Metrology Institute.
NPL	National Physical Laboratory
amu	Atomic mass unit

Some important points in Chemistry

One atomic mass unit(u)	1∕6.02 ✕ 10²³ = 1.66 ✕ 10⁻²⁴g
M₁ = W₁ / 1.66 ✕ 10⁻²⁴	M₁ = atomic mass / molecular mass W₁ = mass of an atom / molecule in gram
Mole	Amount of an any substance containing 6.02 ✕ 10²³ particles.
n₁ = W₁ / M₁	n₁  = Number of moles W₁ = mass in grams M₁ = molecular mass
n₁ = V / 22.4	V = volume in dm³ at STP
n₁ = Number of atoms (or) molecules / NA	NA = 6.02 ✕ 10²³
Empirical formula	Simplest ratio of relative number of atoms of different element in the compound.
Molecular formula	Exact number of atoms in a molecules of the compound.
Excess reactant	Reactant taken in excess amount than required by stoichiometry.

Let Us Remember - Seasons - 2nd class

Let Us Remember - Seasons

• The weather is not the same throughout the year.
• We have 4 main seasons: the summer season, the winter season, the rainy season & the spring season.
• The summer months re April, May & June.
• The rainy season falls in the months of July, August & September.
• The winter season falls in the months of November, December & January.
• February & march are spring months.