Chemistry Presentation

SUKHEDHARA, KATHMANDU ALEVEL AT SAIPAL PRESENTATION OF CHEMISTRY ON ORGANIC COMPOUND & MOLE CONCEPT…

PREPARED BY GROUP “A”

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INTRODUCTION TO THE SUBJECT TO BE PRESENTED. • • • • • •

ORGANIC COMPOUND AROMATIC & ALIPHATIC COMPOUNDS TYPES OF FORMULAE FUNCTIONAL GROUPS MOLECULAR MODELLING MOLE CONCEPT

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BRIEF INTRODUCTION Ø ORGANIC CHEMISTRY IS THE STUDY OF COMPOUNS CONTAINING CARBON AND HYDROGEN ONLY AND OF COMPOUNDS CONTAINING OTHER ELEMENTS IN ADDITION TO CARBON AND HYDROGEN. 

Ø SUCH COMPOUNDS WERE ORIGINALLY DESCRIBED AS ORGINIC AS THEY WERE ALL BELIEVED TO BE ORIGINATED FROM LIVING ORGANISMS. 

Ø AN ORGANIC COMPOUND IS ANY MEMBER OF A LARGE CLASS OF CHEMICAL COMPOUNDS WHOSE MOLECULES CONTAIN CARBON.

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INTERESTING FACTS Ø THE NAME “ORGANIC” IS HISTORICAL,DATING BACK TO THE 19th CENTURY, WHEN IT WAS BELIEVED THAT ORGANIC COMPOUNDS COULD ONLY BE SYNTHESIZED IN LIVING ORGANISMS THROUGH VIS VITALIS- THE “LIFE-FORCE”.

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Ø ALTHOUGH THIS IDEA WAS DISPELLED BY THE SYNTHESIS OF UREA FROM AN INORGANIC COMPOUND, AMMONIUM CYNATE, BY THE GERMAN CHEMIST FRIEDRICH WOHLER IN 1824, WE STILL USE THE TERM ORGANIC.

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Ø OVER 90% OF KNOWN COMPOUNDS CONTAIN CARBON, DESPITE THE EXISTENCE OF SEVERAL ELEMENTS WITH MUCH GREATER NATURAL ABUNDANCE.

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ORGANIC COMPOUNDS Ø Organic means involvement of carbon and Hydrogen with other elements and the involvement of only those two atoms is known as “hydrocarbon”. Ø As single carbon-carbon & carbonhydrogen bonds are relatively unreactive, the reactions of these compounds are typically those involving particular functional continued

AROMATIC & ALIPHATIC COMPOUNDS… • Aromatic compounds contain one or more arene rings .An aromatic hydrocarbon (abbreviated as AH) or arene is a hydrocarbon of which the molecular structure incorporates one or more planar sets of six carbon atoms that are connected by delocalized electrons numbering the same as if they consisted of alternating single and double covalent bonds. • • The term 'aromatic' was assigned before the physical mechanism determining aromaticity was discovered, and was derived from the fact that many of the compounds have a sweet scent. • • This sweet scent actually came from impurities in the compounds (which are not actually aromatic in the sense initially described). • • The configuration of six carbon atoms in aromatic compounds is known as a benzene ring, after the simplest possible such hydrocarbon, benzene. continued

ARENES

THIS IS THE FIGURE OF ARENES continued

ALIPHATIC • ALL THE UNPLEASANT SMELLING COMPOUNDS ARE ALIPHATIC. • HENCE ALKANES AND ALKENES ARE ALIPHATIC COMPOUNDS, WHILST • BENZENE IS THE ONLY COMPOUND WHICH IS ALKENE GROUP BUT IT LIES ON AROMATIC COMPOUND.

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TYPES OF FORMULAE • MOLECULAR FORMULA: Molecular formula of benzene is C6H6. 

• STRUCTURAL FORMULA: Structural formula of hexane is CH3CHCH2CH2CH2CH3. • DISPLAYED FORMULA: Displayed formula of methylamine is continued

TYPES OF FORMULAE • SKELETAL FORMULA:  (used to show the carbon atoms without labeling)  Skeletal formula of Amino pentane is

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TYPES OF FORMULAE 1. T H R E E D IM E N S IO N A L FO R M U LA :

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FUNCTIONAL GROUPS • Classification normally starts with the hydrocarbons: compounds which contain only carbon and hydrogen. Other elements present themselves in atomic configurations called functional groups which have decisive influence on the chemical and physical characteristics of the compound; thus those containing the same atomic formations have similar characteristics, which may be: miscibility with water, acidity/alkalinity, chemical reactivity, oxidation resistance, and others.

• • Each functional group gives raise to a Continued…………………

BASIC CONCEPT OF NAMING HYDROCARBONS 1.The position of an alkyl group is indicated by a number. 2.The number of carbon atoms in the longest chain provides the stem of the name. 3.Numbering starts from the end that produces the lowest possible numbers for the side-chains. For e.g. CH CH3CHCH 2CH2CH3. 3

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MOLE CONCEPT • If molecular weight is expressed in grams, it is called gram molecular weight. One gram molecular weight. One gram atomic weight of an element contains 6.02 x 1023 number of atoms. It was discovered by Avogard and it is known as Avorgado’s number. • When the weight of a substance is taken in accordance with the molecular weight, one mole (6.02 x 1023 ) of its molecules is present in that weight. For e.g. one mole of water represents 18 grams of it because continued

OUR GROUP MEMBERS 1 . PRAKASH DANGOL 2 . KIRAN LIMBU 3 . RAJENDRA BOGATI 4 . HAANG LIMBU • • • LASTLY THANKS ALL OF OUR GROUP MEMBERS AND ESPECIALLY OUR TEACHERS GIVING US THIS OPPURTUNITY .