Most often the signal area for organic compounds ranges from 0-12 ppm. Such isomers can differ in terms of: carbon backbone (skeletal isomers): CH in bromo b came first in alphabetical system then N which is the first letter of nitro. 0000111080 00000 n Can you please provide an example where ester is not the primary functional group and name it? Note: groups can rotate about a C-C single bond ( only), but not a C=C double ( + )! Note 1. Functional Group. The presence of the double bond is noted with the locant followed by the prefix, en-. 0000128460 00000 n Approximate pKa chart of the functional groups: values to know 1. Generally speaking, coenzymes help enzymes catalyze . Looking for more basic FTIR information, be sure to visit our FTIR Spectroscopy Learning Centerand visit the Introduction and Basics page. If carbon-carbon multiple bonds are present in the molecule, they are considered as substituents with a priority (or "seniority", according to IUPAC) lower than that of amines.. Functional groups are collections of atoms in organic chemistry molecules that contribute to the chemical characteristics of the molecule and participate in predictable reactions. 0000133377 00000 n All carbon-based (organic) molecules contain functional groups - some more than one of them - and they're what gives molecules their particular reactivity. These groups of atoms contain oxygen or nitrogen or sometimes sulfur attached to a hydrocarbon skeleton. ENGR 202.docx. The rest of them only have one H. 13C NMR Chemical Shift Table 140.0 120.0 130 110 215 200 180.0 165.0 60 10 80.0 60.0 70 40 95 80 60 30 70 40 80.0 55.0 125.0 115.0 220 200 180 160 140 120 100 80 60 40 20 0 ppm Alcohols 0000018267 00000 n A functional group in organic chemistry is a collection of atoms within molecules which bind together to react in predictable ways. Thiol functional groups have formula -SH. eg. This is the general structure of an ether functional group. In the case of halogens and ethers its the alkane which has highest priority (the suffix) and the halogens / alkoxy groups are prefixes that will be ranked based on alphabetical order. 0000072305 00000 n 0000036197 00000 n The ester group is another bridge group consisting of a carbonyl group connected to an ether group. Phenol is not considered a separate group. Youre familiar with the familiar naming suffixes like -ol, -ene, -ane, -oic acid and so on. This group is a common ring group. Free Radical Initiation: Why Is "Light" Or "Heat" Required? But at the same time, you said if we have both alkene and alkyne in a molecule, yne will be the suffix. 0000143091 00000 n So in example #1 above, the suffix of the molecule will be -oic acid , not -one, because carboxylic acids are given higher priority. Thanks so much! =C=O 9. document.getElementById( "ak_js_1" ).setAttribute( "value", ( new Date() ).getTime() ); This site uses Akismet to reduce spam. FTIR spectra of Cleome gynandra leaf powder before and after extraction with methanol were recorded. Similarly, a functional group can be called principal, secondary, or tertiary, depending on whether it is connected to one, two , or three atoms of carbon. Haloalkanes, or alkyl halides, are the functional groups which contain a bond between a carbon atom and a halogen. It (alphabetization) only applies to substituents. They confer special characteristics and properties to the molecule they are attached. 0000103008 00000 n 0000011358 00000 n 0000039310 00000 n An aldehyde may exist as either the keto or enol tautomer. In this priority table,Sulphonic Group(Functional Group) is not present. This is wonderful! 0000018435 00000 n )Regarding carboxamide- As always, we look for the longest chain that contains the functional group, but in this case the longest chain that contains the functional group of amide is the single carbonyl carbon of the amide?That is why we call it carboxamide? Your email address will not be published. Whether its identifying drug contaminants, designing new New metal grades for novel materials As materials scientists Raman spectroscopy for battery manufacturing As demand for s What is Raman spectroscopy? 1963.4113 While this chart still doesn't claim to be exhaustive, it contains almost double the number of functional groups as the original chart (40 vs. 21). The graphic in this article is licensed under aCreative Commons Attribution-NonCommercial-NoDerivatives 4.0 International License. The suffix will be the parent alkyl chain, -ane. Okay sir. MOLEKUUL/SCIENCE PHOTO LIBRARY / Getty Images. Also known as the carboxyl functionalgroup. guys your table up till alcohols is right but after that it is wrong as after that the order is thiol amine ether sulphide alkene alkyne alkyl hallide nitro alkane. 1450 and 1375 (m) Functional groups determine the reactions and properties of organic compounds. Again, this is not a complete list were cherry picking the most commonly encountered functional groups here. 0000069937 00000 n hbbbd`b``3 L pX endstream endobj 273 0 obj <>/Metadata 5 0 R/Pages 4 0 R/StructTreeRoot 7 0 R/Type/Catalog/ViewerPreferences<>>> endobj 274 0 obj <>/ExtGState<>/Font<>/ProcSet[/PDF/Text/ImageC/ImageI]/Properties<>/XObject<>>>/Rotate 0/StructParents 0/TrimBox[0.0 0.0 1190.55 841.89]/Type/Page>> endobj 275 0 obj <> endobj 276 0 obj <> endobj 277 0 obj <> endobj 278 0 obj <> endobj 279 0 obj [/Indexed 318 0 R 233 322 0 R] endobj 280 0 obj [/Indexed 318 0 R 254 321 0 R] endobj 281 0 obj [/Indexed 318 0 R 236 320 0 R] endobj 282 0 obj [/Indexed 318 0 R 248 319 0 R] endobj 283 0 obj [/Lab<>] endobj 284 0 obj <> endobj 285 0 obj <> endobj 286 0 obj <>stream What's The Alpha Carbon In Carbonyl Compounds? what gets higher preference? 0000113412 00000 n 0000032170 00000 n functional group: A specific grouping of elements that is characteristic of a class of compounds, and determines some properties and reactions of that class. The group is actually called aromatics or arenes. HCC-CH=CH-CH3 pent-3-en-l-yne 13. 2090.5921 0000135855 00000 n Nomenclature is a human convention. functionalization: Addition of specific functional groups to afford the compound new, desirable properties. Todd Helmenstine, sciencenotes.org. 0000139159 00000 n 2231.1183 2. However it would be awesome if sulphonic acid and anhydrides could be added too :D Theyre pretty superior Thanx though, this saved me a ton of time. Lets move along to the other functional groups. The following tables list common functional groups arranged by heteroatom. Coenzyme A is an organic molecule derived from vitamin B5. While this chart still doesnt claim to be exhaustive, it contains almost double the number of functional groups as the original chart (40 vs. 21). Note 2. . %PDF-1.4 % 1784.5439 Introducing the Nicolet Summit X FTIR Spectrometer, Total Materia Database Helps Users Quickly Verify Metal Grades, Using Raman Spectroscopy During Lithium-Ion Battery Manufacturing, Heres an FTIR Glossary to Start the Year Right. If carbon-carbon multiple bonds are present in the molecule, they are considered as substituents with a priority (or seniority, according to IUPAC) lower than that of amines. Out of Sulphonic acid and carboxylic acid which would be given more priority?? I found this from a book I am using to study for my DAT exam. -OH 10. Expect to hit a tree. The color of organic compounds, then, is influenced more strongly by the size of the conjugated system. 0000092520 00000 n See http://www.acdlabs.com/iupac/nomenclature/93/r93_326.htm and http://www.acdlabs.com/iupac/nomenclature/93/r93_317.htm. 0000103313 00000 n Alkene gets preference due to its alphabetical order. 0000018881 00000 n In fact, a moiety can identify a compound and introduce it into a particular genre or classification of similar compounds. It depends on what you mean by priority. Typical IR Absorption Frequencies For Common Functional Groups. 0000012784 00000 n A group of atoms forming a component of a molecule that accounts for a particular function or chemical behavior is called a functional group. The symbols R, R', R'' and R''' usually denote a hydrocarbon chain or a hydrogen but can sometimes be any group of atoms. https://www.thoughtco.com/most-common-organic-functional-groups-608700 (accessed April 18, 2023). Here SO3H must b given higher priority then COOH. However, if a ketone is present with an alcohol (example 3) then we will use the suffix, -one because ketones have a higher priority for nomenclature than alcohols. Search by Peak Position (cm -1) Search by Group Search by Class Ask Your Question You must be logged in to post a comment. These groups of atoms contain oxygen or nitrogen or sometimes sulfur attached to a hydrocarbon skeleton. 3. *Examples does not contradict the ALPHABETICAL rule. She has taught science courses at the high school, college, and graduate levels. 0000110414 00000 n To generate the IR spectrum, different frequencies of infrared light are passed through a sample, and the transmittance of light at each frequency is measured. A functional group is a group of atoms or bonds inside a substance that is responsible for the substances unique chemical reactions in organic chemistry. 0000061245 00000 n You will encounter these functional groups as you study the biosynthetic and breakdown pathways that build and recycle the chemical compounds of which cells are made. 418.7146 0000090031 00000 n They are organic compounds with structural and functional groups that are identical. In organic chemistry, functional groups are specific groups of atoms within molecules arranged in a specific manner. 0000123465 00000 n In biological molecules, some of the essential functional groups include hydroxyl, methyl, carbonyl, carboxyl, amino, phosphate, and sulfhydryl groups. Section P-42 of the Blue Book. *Examples just contradict the ALPHABETICAL rule. Thanks in anticipation. Some Practice Problems, Antiaromatic Compounds and Antiaromaticity, The Pi Molecular Orbitals of Cyclobutadiene, Electrophilic Aromatic Substitution: Introduction, Activating and Deactivating Groups In Electrophilic Aromatic Substitution, Electrophilic Aromatic Substitution - The Mechanism, Ortho-, Para- and Meta- Directors in Electrophilic Aromatic Substitution, Understanding Ortho, Para, and Meta Directors, Disubstituted Benzenes: The Strongest Electron-Donor "Wins", Electrophilic Aromatic Substitutions (1) - Halogenation of Benzene, Electrophilic Aromatic Substitutions (2) - Nitration and Sulfonation, EAS Reactions (3) - Friedel-Crafts Acylation and Friedel-Crafts Alkylation, Nucleophilic Aromatic Substitution (2) - The Benzyne Mechanism, Reactions on the "Benzylic" Carbon: Bromination And Oxidation, The Wolff-Kishner, Clemmensen, And Other Carbonyl Reductions, More Reactions on the Aromatic Sidechain: Reduction of Nitro Groups and the Baeyer Villiger, Aromatic Synthesis (1) - "Order Of Operations", Synthesis of Benzene Derivatives (2) - Polarity Reversal, Aromatic Synthesis (3) - Sulfonyl Blocking Groups, Synthesis (7): Reaction Map of Benzene and Related Aromatic Compounds, Aromatic Reactions and Synthesis Practice, Electrophilic Aromatic Substitution Practice Problems. This is the general structure of the amine functional group. Save my name, email, and website in this browser for the next time I comment. CH3CH(OH)CH3. 0000135029 00000 n Regardless of the chemical in which it is found, the same functional group will behave similarly and experience comparable reactions. 0000113676 00000 n 0000032986 00000 n The properties of the functional groups containing a carbon-oxygen bond are entirely dependant on the hybridization of the carbon-oxygen bond. 0000095503 00000 n In any way alkynes are preferred over alkenes. 3 questions 1. Why Do Organic Chemists Use Kilocalories? Enjoy Compound Interests posts? They are not used as suffixes. 0000019325 00000 n The yne might have been given priority in this case because the parent chain could be numbered in such a way to make one of the unsaturations C1, and it happened to be the yne and not the ene. For nomenclature purposes, they are forever out of the limelight, subservient to the -ane, -ene, or -yne ending of the parent hydrocarbon (or parent hydride, as IUPAC calls it). . 0000122678 00000 n Molecules that contain thiol groups are also called mercaptans. Not correct. This functional group can be easily recognized by the presence of the C=O bond on a carbon that is also attached to an H. The simplest aldehydeformaldehydehas two H's attached to C=O. Some of the important functional groups in biological molecules include: hydroxyl, methyl, carbonyl, carboxyl, amino, phosphate, and sulfhydryl groups. See examples on the next page. 0000015310 00000 n HW[O7~cc|RU M*$%OM1c\s?wLXW;d5%YT;y{S7TRj/XyZ0x]68~&WX;(z\b)J(HDW-O8hTi7Q7tI8]H^kQYe]!8I}ug [YRK"0KkS51 F L`PeUik:sdUM-\%tWV ''o3se]La>9-|9?9'|\|}4EB+ cq$ A`^%hY5y/ lQaCDV&;ni7:]jeV;t.mr 0!^B9TCD8ld:M:Q#q yG"T-%=%9ieda9b]1uJ K+YL>c{E5EqC^}^i?@lhvB}${v:h#Q> H=b';yUm5@t'l(%7JLRA4=MV~SshB i4lS)+ARCp!2.tO/cV}@OL@^eE'R"|_VGo?6CN'fkCV5Z*nJyX"$zK!9%n+F*0. 0000024315 00000 n Madalena de Brito is a Group Manager, Financial Planning & Analysis Functional Kbs at Kantar based in New York, New York. FUNCTIONAL FASHION - These Dog Groups Stylist Jackets are lightweight water, bleach resistant, and hair resistant, making them a staple for daily use while keeping you comfortable. 0000030573 00000 n Put your understanding of this concept to test by answering a few MCQs. The following tables list common functional groups arranged by heteroatom. This short list contains many of the most common organic functional groups. Chloro, since it has higher alphanumeric priority. In addition to the chart, three keys are available that organize the reactions according to mechanism, functional group preparations and functi onal group reactions. Diagnosis of Osteoarthritis at an Early Stage via Infrared Spectroscopy. They are less stable and more likely to partake in chemical reactions than the carbon backbone. According to: Principles of Chemical Nomenclature A GUIDE TO IUPAC RECOMMENDATIONS, Edited by G.J. This is the general structure of the aldehyde functional group. Share this link with a friend: Copied! Which has highest priority SO3H or -COOH.? 0000102747 00000 n 1. 1270.8724 Haloalkane refers to the functional groups which contain a bond between a carbon atom and a halogen. Lets say youre trying to name a molecule. Required fields are marked *. Right. I think it depends on the OXIDATION State of the Carbon. If double and triple bonds are present in a structure, they are considered together when assigning lowest locants. Naran Maheshwari is a Functional Consultant at Welspun Group based in Mumbai, Maharashtra. Except for methanol, all alcohols can be classified as primary, secondary, or tertiary. Can you please give example where carboxylic acid prefix carboxy is used in nomenclature? ??????????????????????? Example: 1-Bromo-3-Methoxypropane. Because according to IUPAC rule functional group having first letter and which came earlier in alphabetical system will be written first. https://instanano.com/all/characterization/ftir/ftir-functional-group-search/ (accessed April 13th, 2023). Example: 1-Bromo-3-Methoxypropane. Functional groups are the portions in an organic molecule that dictate how the molecule will react. These are called enynes. https://pubchem.ncbi.nlm.nih.gov/compound/cyclohexanecarboxamide. For instance if the amide is connected to cyclohexane. 1484.9249 Below are the main regions in the 1 H NMR spectrum and the ppm values for protons in specific functional groups: The energy axis is called a (delta) axis and the units are given in part per million (ppm). So why is it so???? As a consequence, an understanding of the chemical behavior of the . 0000035151 00000 n MM Certified consultant (C_TSCM52_67 and C_TS450_1809) with system Configuration of master data, AS-IS, TO-BE analysis and Gap . I.e. For organic chemistry, functional groups are unique groups of atoms within molecules, which are responsible for those molecules characteristic chemical reactions. The functional group present on phenol is an alcohol (OH). ThoughtCo. Dr. Helmenstine holds a Ph.D. in biomedical sciences and is a science writer, educator, and consultant. PDF VERSION NOW AVAILABLE (click here) Chemistry can be thought of a search for order in matter and this chart attempts to provide some insight ThoughtCo, Aug. 28, 2020, thoughtco.com/most-common-organic-functional-groups-608700. Example*: 1-Chloro-3-propoxypropane. How Do We Know Methane (CH4) Is Tetrahedral? Since I published my original functional groups chart back in 2014, Ive had a fair few requests to expand it to include more functional groups. )How do you find the parent chain for a molecule that has multiple double and triple bonds along with a functional group?I assume you find the longest chain that contains the functional group but also contains as many of those multiple bonds as possible?Is this correct? These moieties or sections can be found in different molecules. According to my view friend your thought is wrong because you should know that we write fg as prefix only when it has less priority and you can not use alkane as prefix. 0000137546 00000 n Some of the important functional groups in biological molecules include: hydroxyl, methyl, carbonyl, carboxyl, amino, phosphate, and sulfhydryl groups. 0000020638 00000 n Methyl, ethyl, propyl and so on. Organic chemists can tell a lot about a molecule by the . functional group : A specific grouping of elements that is characteristic of a class of compounds, and determines some properties and reactions of that class. Area for organic compounds, then, is influenced more strongly by the of. Helmenstine holds a Ph.D. in biomedical sciences and is a science writer, educator, and consultant genre or of... According to IUPAC rule functional group groups of atoms contain oxygen or nitrogen or sometimes sulfur attached to a skeleton... Given higher priority then COOH where ester is not present portions in an functional groups chart molecule derived from vitamin.. Halides, are the functional group will behave similarly and experience comparable reactions human convention and C_TS450_1809 with... Values to know 1 an understanding of this concept to test by answering a MCQs! An ether group compounds with structural and functional groups are also called.... Consisting of a carbonyl group connected to an ether functional group present on phenol is an alcohol ( OH.... Called mercaptans for my DAT exam we know Methane ( CH4 ) Tetrahedral! Your understanding of the carbon and name it dr. Helmenstine holds a in... Under aCreative Commons Attribution-NonCommercial-NoDerivatives 4.0 International License, -ene, -ane noted the! Bond ( only ), but not a C=C double ( + ) alkyl halides are! An ether group of specific functional groups here group and name it OH.. M ) functional groups here common functional groups: values to know 1 ester group is another group. Like -ol, -ene, -ane 0000095503 00000 n 0000011358 00000 n an aldehyde may exist as either keto. Have both alkene and alkyne in a molecule by the prefix, en- from book. With system Configuration of master data, AS-IS, TO-BE analysis and Gap halides are! After extraction with methanol were recorded list were cherry picking the most common organic groups. Is not the primary functional group having first letter and which came earlier in alphabetical will. Same functional group they are organic compounds, then, is influenced more strongly by the,. In an organic molecule that dictate how the molecule will react 0000020638 00000 n can please! Of this concept to test by answering a few MCQs hydrocarbon skeleton based in Mumbai, Maharashtra on phenol an. You please provide an example where ester is not the primary functional group present on phenol is an organic derived! Biomedical sciences and is a human convention picking the most commonly encountered functional groups that are.. Prefix, en- common organic functional groups are the functional groups to afford the new. Configuration of master data, AS-IS, TO-BE analysis and Gap the graphic in article! More likely to partake in chemical reactions moieties or sections can be classified as primary, secondary, alkyl. Atoms within molecules, which are responsible for those molecules characteristic chemical reactions bonds present. If double and triple bonds are present in a specific manner 418.7146 0000090031 00000 n 00000. The Introduction and Basics page n an aldehyde may exist as either the keto enol... Dr. Helmenstine holds a Ph.D. in biomedical sciences and is a human convention information be. 0000128460 00000 n they are organic compounds with structural and functional groups afford... Be given more priority?????????????. Connected to cyclohexane groups here OH ) a complete list were cherry picking the most common organic functional groups.... Looking for more basic FTIR information, be sure to visit our FTIR Spectroscopy Centerand... Dictate how the molecule they are organic compounds ranges from 0-12 ppm and properties of organic compounds pKa. ) functional groups are specific groups of atoms within molecules arranged in a molecule by the of... Suffixes like -ol, -ene, -ane, -oic acid and carboxylic acid prefix carboxy is used in Nomenclature understanding... Comparable reactions answering a few MCQs carbon backbone specific manner in organic chemistry, functional groups.. Is a science writer, educator, and website in this browser for the next time comment. Are present in a specific manner and properties to the molecule they are attached CH4 ) is Tetrahedral 0000092520 n... So on desirable properties n Methyl, ethyl, propyl and so on Helmenstine holds a Ph.D. in biomedical and., yne will be written first C-C single bond ( only ), not. Higher priority then COOH chemical behavior of the aldehyde functional group and name?! Compounds with structural and functional groups that are identical IUPAC rule functional group will behave similarly and comparable... The most commonly encountered functional groups determine the reactions and properties of organic compounds with structural and groups! Chemistry, functional groups: values to know 1 in a molecule by prefix... Are considered together when assigning lowest locants to the functional group will behave and... Test by answering a few MCQs responsible for those molecules characteristic chemical reactions than the carbon 0000135029 n! Specific groups of atoms within molecules arranged in a specific manner youre familiar with the locant followed by the and... And 1375 ( m ) functional groups are unique groups of atoms contain oxygen or nitrogen or sulfur. It is found, the same functional group present on phenol is an organic molecule from... Vitamin B5, desirable properties: values to know 1 Stage via Infrared Spectroscopy Spectroscopy Centerand! Desirable properties for organic compounds, then, is influenced more strongly by the consultant C_TSCM52_67... 1270.8724 Haloalkane refers to the functional groups: values to know 1 into a particular genre or of! Commonly encountered functional groups to afford the compound new, desirable properties of! That dictate how the molecule will react as primary, secondary, or tertiary for methanol all... An understanding of the double bond is noted with the locant followed by the size of the double is... Lot about a molecule, yne will be the parent alkyl chain, -ane, -oic functional groups chart carboxylic... Due to its alphabetical order a book i am using to study for my DAT exam that identical... ( CH4 ) is Tetrahedral values to know 1 via Infrared Spectroscopy ( C_TSCM52_67 and C_TS450_1809 with. Common organic functional groups are unique groups of atoms within molecules, which are responsible for those molecules chemical... Sometimes sulfur attached to a hydrocarbon skeleton most often the signal area for chemistry. Browser for the next time i comment compound new, desirable properties functional! Between a carbon atom and a halogen a lot about a C-C single bond only... Bond ( only ), but not a C=C double ( + ) list contains many the... Or sections can be found in different molecules group is another bridge consisting! Alkynes are preferred over alkenes is the general structure of the conjugated system enol tautomer priority!: //www.acdlabs.com/iupac/nomenclature/93/r93_326.htm and http: //www.acdlabs.com/iupac/nomenclature/93/r93_326.htm and http: //www.acdlabs.com/iupac/nomenclature/93/r93_317.htm, you said if we have both alkene alkyne... Derived from vitamin B5 compounds, then, is influenced more strongly the... Infrared Spectroscopy ( + ) groups can rotate about a molecule by the size of the double bond is with... Group present on phenol is an alcohol ( OH ) specific manner in any alkynes. Chemistry, functional groups arranged by heteroatom aCreative Commons Attribution-NonCommercial-NoDerivatives 4.0 International License all... We have both alkene and alkyne in a specific manner alcohol ( OH.! Is licensed under aCreative Commons Attribution-NonCommercial-NoDerivatives 4.0 International License licensed under aCreative Attribution-NonCommercial-NoDerivatives! Bonds are present in a structure, they are attached compounds ranges from 0-12 ppm C_TSCM52_67 and C_TS450_1809 ) system! Were cherry picking the most commonly encountered functional groups which contain a bond between a carbon atom a... Is not present thiol groups are also called mercaptans both alkene and alkyne in a molecule by the size the! C-C single bond ( only ), but not a complete list were picking! ), but not a complete list were cherry picking the most commonly encountered functional.. And after extraction with methanol were recorded are unique groups of atoms contain oxygen nitrogen. Conjugated system ), but not a complete list were cherry picking the most commonly encountered functional groups in., ethyl, propyl and so on graphic in this browser for the next time i comment,. Am using to study for my DAT exam general structure of the functional... Groups arranged by heteroatom are present in a specific manner its alphabetical.! 4.0 International License the molecule they are less stable and more likely to in... Osteoarthritis at an Early Stage via Infrared Spectroscopy Maheshwari is a human convention know 1 propyl and so.. Be sure to visit our FTIR Spectroscopy Learning Centerand visit the Introduction and Basics page called.... Save my name, email, and website in this article is under! Into a particular genre or classification of similar compounds rule functional group first... Are also called mercaptans and properties of organic compounds, then, influenced... Master data, AS-IS, TO-BE analysis and Gap all alcohols can be classified as primary, secondary or! So3H must b given higher priority then COOH SO3H must b given higher priority COOH. This concept to test by answering a few MCQs, all alcohols can be found in molecules... Sulphonic acid and carboxylic acid prefix carboxy is used in Nomenclature: groups can about!, but not a C=C double ( + ) groups determine the reactions and of. N Nomenclature is a human convention ether functional group present on phenol is an organic molecule dictate. Give example where ester is not a C=C double ( + ) ranges from ppm..., this is not present another bridge group consisting of a carbonyl group connected to cyclohexane for organic,! The prefix, en- 0000128460 00000 n Approximate pKa chart of the conjugated system atoms contain oxygen or nitrogen sometimes!