Gian Posted November 27 Posted November 27 (edited) Compounds are 2 or more elements chemically combined, and these also come under the heading of molecules. Molecules are chemical combinations which may involve 2 of the SAME and/ or compounds. So all compounds are all molecules, but not all molecules are compounds. So the oxygen in breathable air is a molecule O2, that is 2 oxygen atoms combined, but it's not a compound Is this right? I'm age 28 but my science level is about that of a 12yo so please keep answers appropriate to a kid! Best GIAN❤️XXX Edited November 27 by Gian 1
studiot Posted November 27 Posted November 27 Just now, Gian said: Compounds are 2 or more elements chemically combined, and these also come under the heading of molecules. Molecules are chemical combinations which may involve 2 of the SAME and/ or compounds. So all compounds are all molecules, but not all molecules are compounds. So the oxygen in breathable air is a molecule O2, that is 2 oxygen atoms combined, but it's not a compound Is this right? I'm age 28 but my science level is about that of a 12yo so please keep answers appropriate to a kid! Best GIAN❤️XXX Absolutely spot on. +1 Without getting too technical, here is a little bit extra. Both Compounds and Molecules have a fixed formula which means that the elements always have the same numbers attached. So ethane - C2H6 - is a different compound from propane - C3H8 , although both have the same proportions between the carbon and the hydrogen - Cn H2n+2 The next step up is called a mixture or a solution, where two or more compounds can appear in basically any proportion.
Gian Posted November 27 Author Posted November 27 (edited) 1 hour ago, studiot said: The next step up is called a mixture or a solution, where two or more compounds can appear in basically any proportion. Brilliant!!! This is the first occasion I've got something right first time on this site!! Next I'll be working for nasa!!! And mixtures or solutions could just be something like seawater; sodium and H2O mixed together? Cheerz GIAN🙂 Edited November 27 by Gian
studiot Posted November 27 Posted November 27 Just now, Gian said: Brilliant!!! This is the first occasion I've got something right first time on this site!! Next I'll be working for nasa!!! And mixtures or solutions could just be something like seawater; sodium and H2O mixed together? Cheerz GIAN🙂 Yes we normally think of solutions as dissolving something like salt or sugar in water or another liquid like alcohol or benzene. Salt is actually a compound sodium chloride NaCl. If I just added pure sodium to water the reaction is so violent it could catch fire. this is a good video; sorry I don't know how to skip the ad at the beginning. Have you had any thoughts as to why the elements in a molecule stay together ? In other words what holds the molecule together ?
exchemist Posted November 27 Posted November 27 (edited) 5 hours ago, Gian said: Compounds are 2 or more elements chemically combined, and these also come under the heading of molecules. Molecules are chemical combinations which may involve 2 of the SAME and/ or compounds. So all compounds are all molecules, but not all molecules are compounds. So the oxygen in breathable air is a molecule O2, that is 2 oxygen atoms combined, but it's not a compound Is this right? I'm age 28 but my science level is about that of a 12yo so please keep answers appropriate to a kid! Best GIAN❤️XXX Actually this is not correct, because not all compounds are molecules. There are also giant structures, both ionic (such as common salt) and covalent, (such as quartz). These compounds are not molecular in nature but are indefinitely extended arrays of atoms, with regular repeating units that correspond to the formula of the compound: NaCl i.e. one Na+ to every Cl-, and SiO₂, i.e. one Si atom with 4 covalent bonds to every 2 O atoms with 2 covalent bonds each. (Metals are also a 3rd type of giant structure, but these are generally not chemical compounds.) But yes, you are right that oxygen and nitrogen are both diatomic molecules: O=O and N≡N. Carbon dioxide is a triatomic molecule: O=C=O. (Oxygen also forms a triatomic molecule, ozone, but that is very reactive and not good to breathe at all - though it does find some application in disinfecting public swimming baths.) Edited November 27 by exchemist 1
Gian Posted November 28 Author Posted November 28 21 hours ago, studiot said: Yes we normally think of solutions as dissolving something like salt or sugar in water or another liquid like alcohol or benzene. Salt is actually a compound sodium chloride NaCl. If I just added pure sodium to water the reaction is so violent it could catch fire. this is a good video; sorry I don't know how to skip the ad at the beginning. Have you had any thoughts as to why the elements in a molecule stay together ? In other words what holds the molecule together ? Thanks Mr Studiot! and thanks for the vid too; going to have to look at it a few times to really get it, but like all the best learning tools it motivates me to find out more, and thanks for keeping it simple (alot of the replies I get on this site use hifalutin jargon which I don't yet understand.) So sodium is a metal?? Didn't know that, So salt is 1 atom of sodium + 1 atom of chlorine? And thanks for the stuff about ethane and propane All I know about how the contents of molecules and compounds are held together is that they are "chemically bonded" according to the kids' books and vids I'm looking at and can be difficult to separate, so perhaps you can send me a link to some info about it please? (suitable for 12yo's) 19 hours ago, exchemist said: Actually this is not correct, because not all compounds are molecules. There are also giant structures, both ionic (such as common salt) and covalent, (such as quartz). These compounds are not molecular in nature but are indefinitely extended arrays of atoms, with regular repeating units that correspond to the formula of the compound: NaCl i.e. one Na+ to every Cl-, and SiO₂, i.e. one Si atom with 4 covalent bonds to every 2 O atoms with 2 covalent bonds each. (Metals are also a 3rd type of giant structure, but these are generally not chemical compounds.) But yes, you are right that oxygen and nitrogen are both diatomic molecules: O=O and N≡N. Carbon dioxide is a triatomic molecule: O=C=O. (Oxygen also forms a triatomic molecule, ozone, but that is very reactive and not good to breathe at all - though it does find some application in disinfecting public swimming baths.) Thanks Mr Exchemist. So in simplest possible terms how do you define a molecule as opposed to these other giant structures? Cheerz GIAN🙂XXX (science age; 12) 1
exchemist Posted November 28 Posted November 28 (edited) 1 hour ago, Gian said: Thanks Mr Studiot! and thanks for the vid too; going to have to look at it a few times to really get it, but like all the best learning tools it motivates me to find out more, and thanks for keeping it simple (alot of the replies I get on this site use hifalutin jargon which I don't yet understand.) So sodium is a metal?? Didn't know that, So salt is 1 atom of sodium + 1 atom of chlorine? And thanks for the stuff about ethane and propane All I know about how the contents of molecules and compounds are held together is that they are "chemically bonded" according to the kids' books and vids I'm looking at and can be difficult to separate, so perhaps you can send me a link to some info about it please? (suitable for 12yo's) Thanks Mr Exchemist. So in simplest possible terms how do you define a molecule as opposed to these other giant structures? Cheerz GIAN🙂XXX (science age; 12) A molecule is a group of atoms joined by chemical bonds, constituting the smallest complete subunit of a chemical compound that can take part in chemical reactions. In the case of giant structures there is no such subunit. You could almost say that, with a giant structure, the whole structure could be thought of as one giant molecule, but even that would not be entirely right as it has no fixed size: it's size simply depends on how big the entire crystal is! Edited November 28 by exchemist 1
Gian Posted November 28 Author Posted November 28 21 minutes ago, exchemist said: A molecule is a group of atoms joined by chemical bonds, constituting the smallest complete subunit of a chemical compound that can take part in chemical reactions. In the case of giant structures there is no such subunit. Thanx, Can you give me an example of a "smallest complete subunit" please? Cheerz GIAN🙂XXX (science age; 12)
studiot Posted November 28 Posted November 28 Just now, Gian said: All I know about how the contents of molecules and compounds are held together is that they are "chemically bonded" according to the kids' books and vids I'm looking at and can be difficult to separate, so perhaps you can send me a link to some info about it please? (suitable for 12yo's) Chemically bonded. Exactly right again. +1 I was avoiding talking about these first off because the general concept of chemical bonding has to be understood before tackling the more complicated matters such as exchemist is talking about. (Giant structures). Chemical bonds are the answer to my question "what holds molecules together", but they also hold other groupings called chemical species together as well, including our own DNA. To start with we divide chemical bonding into Primary bonds which are generally strong or very strong and conform to a few simple rules. and Secondary bonds which are mostly less strong and have a much more flexible rulebook. I am going to be away again for a few days so ask you further questions now or we can continue to develop this after Wednesday of next week. 1
exchemist Posted November 28 Posted November 28 1 hour ago, Gian said: Thanx, Can you give me an example of a "smallest complete subunit" please? Cheerz GIAN🙂XXX (science age; 12) The smallest would be a monatomic molecule, for instance any of the inert gases (Helium, Neon, Argon, Krypton, Xenon). These atoms don't form chemical bonds at all, or only with great difficulty, so as substances they are composed of single atoms. So in this case, the atom and the molecule are one and the same.
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