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A couple of reasons. Firstly, a sextuple bond involves six electron pairs, twelve bonding electrons in total. On small atoms, there are simply not enough orbitals to be able to point in the correct orientation for constructive interference (i.e, for a bond to be formed). Secondly, these electrons have to be distributed over a larger surface area to be stable, otherwise the electron pairs repel too much for the bond to be energetically stable, so these bonds are only possible for larger atoms. Due to electron repulsion, these bonds are relatively unstable on their own, and are usually stabilised by large (usually bidentate) ligands.
The more complex reason refers to Molecular Orbital Theory. If only using p- and s-orbitals, or even hybridised orbitals, the maximum number of orbitals per atom is four, so only eight molecular orbitals can be formed on a diatomic molecule: four bonding and four anti-bonding orbitals. This means that the highest bond order possible would be four, but due to the placment of molecular orbital energy levels, the highest bond order is three. D-orbitals are required for quintuple/sextuple bonds, and d-shell chemistry is less well-studied than the s- or p-blocks. This d-orbital interaction is most energetically favourable for metals, which do not usually exhibit covalent bonding, since metallic bonding is energetically preferable. Dimolybdenum (one of the two compounds known with a sextuple bond) only exists at 7K (seven degrees above absolute zero) in the gaseous phase, at very low energy.
So that's why higher bond orders than three are almost unheard of. However more research is currently going into these electron-dense bonds due to their unusual chemistry.
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∙ 9y ago
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Is a covalent bond a double bond?
A double bond is a covalent bond, but not all covalent bonds are double bonds; some bonds may be single or triple (or even in rare cases, quadruple) instead.
How many types of bond can carbon atom form?
Single, double, and triple covalent bonds
Are covalent bonds formed between metals and metals?
Covalent bonds can be formed between metal atoms, but such compounds are relatively rare. The bonds in a solid metal are usually called "metallic" rather than covalent bonds, because at least some of the valence electrons in a solid metal are shared throughout the boundaries of the solid rather than being present predominantly in the space between any two particular metal atom nuclei.
What type of bond would phosphorus and oxygen form?
oxygen normally forms a convalent bond with one or two other oxygen atoms. as well as oxygen atoms forming oxygen molecules, oxygen atoms tend to form bonds with most of the other elements to form oxides. oxygen atoms on there own are rare. as for phosphorous.........
Can covalent compounds dissolve in water?
You can NOT dissolve 'covalent BONDS' because a bond is one couple of two electrons which hold their two 'parent' atoms together in one molecule.Try asking the question again with what you want to know, not what you have only 'heard of'.
Is carbon likely to make covalent bonds or ionic bonds?
Carbon typically forms covalent bonds. It is rare for it to form ionic bonds.
Is a covalent bond a double bond?
A double bond is a covalent bond, but not all covalent bonds are double bonds; some bonds may be single or triple (or even in rare cases, quadruple) instead.
How many types of bond can carbon atom form?
Single, double, and triple covalent bonds
How many types of bonds can atom form?
Carbon form generally covalent bonds; ionic bonds are rare.
A carbon atom can form no more than this number of bonds?
A carbon atom can typically only form 4 covalent bonds, but there are rare special cases in which it may form more than 4 to create an expanded octet.
Are covalent bonds formed between metals and metals?
Covalent bonds can be formed between metal atoms, but such compounds are relatively rare. The bonds in a solid metal are usually called "metallic" rather than covalent bonds, because at least some of the valence electrons in a solid metal are shared throughout the boundaries of the solid rather than being present predominantly in the space between any two particular metal atom nuclei.
How many bonds can Iodine form with hydrogen?
Like all other halogens, usually one. Like all elements in or below the third row of the periodic table, it is able to make additional bonds in some cases, though those are rare. One example is the triiodide ion, where one iodine makes two bonds.
Do carbon atoms tend to form four convelent bonds?
Yes. It's very rare that they form more, or less than 4 covalent bonds, as this could create a charge on the carbon atom, making it unstable. The reason the number is 4 is because carbon has 4 electrons in its outer shell, meaning it needs another 4 to fill this outer shell. The bonds tend to be covalent, because carbon does not like carrying a charge, so it would not form a stable ionic bond.
What type of bond would phosphorus and oxygen form?
oxygen normally forms a convalent bond with one or two other oxygen atoms. as well as oxygen atoms forming oxygen molecules, oxygen atoms tend to form bonds with most of the other elements to form oxides. oxygen atoms on there own are rare. as for phosphorous.........
Can covalent compounds dissolve in water?
You can NOT dissolve 'covalent BONDS' because a bond is one couple of two electrons which hold their two 'parent' atoms together in one molecule.Try asking the question again with what you want to know, not what you have only 'heard of'.
Why is ionic bond formed when the electronegativity is more than 1.7?
A large difference in electronegativity means that one elemnt gives up its electron completly and the other accepts it. A difference of 1.7 is only a "rule of thumb" based on observations of which combinations of elemnts are ionic and which covalent. Covalent and ionic are "two ends of the spectrum" , pureionic bonds are RARE, usually there is small amount of covalency.
A hydrogen bond can form between a hydrogen atom of one molecule and which atom of another molecule?
since hydrogen atom has no electron in its shell, it acquires positive charge. when a negatively charged atom comes in contact with hydrogen atom, it donates h atom a electron to make a covalent bond. but when it breaks the negative atom restores its electron.
