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#OTD a year ago, Moderna’s RNA vaccine became the first #COVID19 vaccine to enter phase 1 trials. The latest #ChemVsCOVID graphic with the Royal Society of Chemistry takes a brief look at how prior research helped COVID vaccines reach this point quickly: https://ift.tt/3cE5xHR https://ift.tt/3rV4v0F
In one boring history lesson, you and your friend (who both love chemistry) are doodling displayed formulas in the back of your textbook. You both decide to draw C5H12 - however, when you come to name what you’ve drawn, your friend has something completely different. You know what you’ve drawn is pentane and your friend knows what they’ve drawn is 2,3-dimethylpropane. So which one is C5H12?
The answer is both! What you and your friend have hypothetically drawn are structural isomers of C5H12 (another is 2-methylbutane). These are compounds which have the same molecular formula but different structural formulas.
Isomers are two or more compounds with the same formula but a different arrangement of atoms in the molecule and often different properties.
There are several different kinds of structural isomers: chain, positional and functional group.
Chain isomerism happens when there is more than one way of arranging carbon atoms in the longest chain. If we continue with the example C5H12, it exists as the three chain isomers shown above. Chain isomers have similar chemical properties but different physical properties because more branched isomers have weaker Van der Waals and therefore lower boiling points.
Positional isomers have the same carbon chain and the same functional group but it is attached at different points along the chain.
This is a halogenoalkane. The locant “1″ describes where the chlorine is on the chain. For more on naming organic compounds, check out my nomenclature post.
The final type of isomer you need to know is a functional group isomer. This is a compound with the same molecular formula but a different functional group. For example, C2H6O could be ethanol or methoxymethane.
And surprisingly, that is all you need to know for the AS exam. There are also things called stereoisomers but those will be covered next year. Just make sure you know how to name and draw the three different kinds of structural isomers for the exam. Practice makes perfect!
SUMMARY
Structural isomers are compounds which have the same molecular formula but different structural formulas.
Isomers are two or more compounds with the same formula but a different arrangement of atoms in the molecule and often different properties.
There are several different kinds of structural isomers: chain, positional and functional group.
Chain isomerism happens when there is more than one way of arranging carbon atoms in the longest chain. Chain isomers have similar chemical properties but different physical properties because more branched isomers have weaker Van der Waals and therefore lower boiling points.
Positional isomers have the same carbon chain and the same functional group but it is attached at different points along the chain.
A functional group isomer is a compound with the same molecular formula but a different functional group.
Happy studying!
This is the first in my short series of the three main types of bond - ionic, metallic and covalent. In this, you’ll learn about the properties of the compounds, which atoms they’re found between and how the bonds are formed. Enjoy!
When electrons are transferred from a metal to a non-metal, an ionic compound is formed. Metals usually lose electrons and non-metals usually gain them to get to a noble gas configuration. Transition metals do not always achieve this.
Charged particles that have either lost or gained electrons are called ions and are no longer neutral - metal atoms lose electrons to become positive ions (cations) whereas non-metals gain electrons to become negative ions (anions).
The formation of these ions is usually shown using electron configurations. Make sure you know that the transfer of electrons is not the bond but how the ions are formed.
An ionic bond is the electrostatic attraction between oppositely charged ions.
You need to know how to explain how atoms react with other atoms and for this the electron configurations are needed. You can use dot and cross diagrams for this.
Ionic solids hold ions in 3D structures called ionic lattices. A lattice is a repeating 3D pattern in a crystalline solid. For example, NaCl has a 6:6 arrangement - each Na+ ion is surrounded by 6 Cl- and vice versa.
Ionic solids have many strong electrostatic attractions between their ions. The crystalline shape can be decrepitated (cracked) on heating. Ionic Lattices have high melting and boiling points since they need more energy to break because atoms are held together by lots of strong electrostatic attractions between positive and negative ions. The boiling point of an ionic compound depends on the size of the atomic radius and the charge of the ion. The smaller the ion and the higher the charge, the stronger attraction.
Look at this diagram. It shows how atomic radius decreases across a period regularly. This is not the case with the ions. Positive ions are usually smaller than the atoms they came from because metal atoms lose electrons meaning the nuclear charge increases which draws the electrons closer to the nucleus. For negative ions, they become larger because repulsion between electrons moves them further away - nuclear charge also decreases as more electrons to the same number of protons.
Ionic substances can conduct electricity through the movement of charged particles when molten or dissolved (aqueous). This is because when they are like this, electrons are free to move and carry a charge. Ionic solids cannot conduct electricity.
Ionic compounds are usually soluble in water. This is because the polar water molecules cluster around ions which have broken off the lattice and so separate them from each other. Some substances like aluminium oxide have too strong electrostatic attractions so water cannot break up the lattice - it is insoluble in water.
Molecular ions such as sulfate, nitrate, ammonium or carbonate can exist within ionic compounds. These compounds may have covalent bonds within the ions but overall they are ionic and exhibit thee properties described above.
SUMMARY
When electrons are transferred from a metal to a non-metal, an ionic compound is formed.
Charged particles that have either lost or gained electrons are called ions and are no longer neutral - metal atoms lose electrons to become positive ions (cations) whereas non-metals gain electrons to become negative ions (anions).
The formation of these ions is usually shown using electron configurations. The transfer of electrons is not the bond but how the ions are formed.
An ionic bond is the electrostatic attraction between oppositely charged ions.
Ionic solids hold ions in 3D structures called ionic lattices. A lattice is a repeating 3D pattern in a crystalline solid.
Ionic solids have many strong electrostatic attractions between their ions. The crystalline shape can be decrepitated (cracked) on heating.
Ionic Lattices have high melting and boiling points since they need more energy to break because atoms are held together by lots of strong electrostatic attractions between positive and negative ions.
The boiling point of an ionic compound depends on the size of the atomic radius and the charge of the ion. The smaller the ion and the higher the charge, the stronger attraction.
Positive ions are usually smaller than the atoms they came from because metal atoms lose electrons meaning the nuclear charge increases which draws the electrons closer to the nucleus. Negative ions become larger because repulsion between electrons moves them further away - nuclear charge also decreases as more electrons to the same number of protons.
Ionic substances can conduct electricity through the movement of charged particles when molten or dissolved (aqueous). This is because when they are like this, electrons are free to move and carry a charge. Ionic solids cannot conduct electricity.
Ionic compounds are usually soluble in water because the polar water molecules cluster around ions which have broken off the lattice and so separate them from each other.
Some substances like aluminium oxide have too strong electrostatic attractions so water cannot break up the lattice - it is insoluble in water.
Molecular ions such as sulfate, nitrate, ammonium or carbonate can exist within ionic compounds. These compounds may have covalent bonds within the ions but overall they are ionic and exhibit thee properties described above.
Today is #InternationalMakeUpDay! Here’s a graphic looking at the various components of nail polish 💅 https://ift.tt/32fnwAh https://ift.tt/3jWclTk
What comes to mind when you think of alcohol? Probably alcoholic drinks like beer or wine. But in organic chemistry alcohols are an important and versatile family of compounds. In this episode of Crash Course Organic Chemistry, we’ll use alcohols as a starting point to get other types of compounds like ethers, epoxides, and more!
finally, some content! this was a quick info graphic I drew up on Procreate to revise for my ochem test tomorrow. disclaimer: I used information from this source (https://www.masterorganicchemistry.com/2010/05/24/imines-and-enamines/) since my own notes are based off lectures I received at my university that I’m not really allowed to share without heavy modification.
general post disclaimer: I’m an undergraduate student studying biochemistry and genetics. Posts are made for the purposes of education, revision and aesthetics. Not all the content I produce can be taken as entirely accurate and I do not take responsibility for errors made as a result of using this resource. Always consult course textbooks and lectures to aid in your specific learning outcomes. Do not repost without the original caption citing any extra references I used to make this post or remove my watermark. Other posts can be found on my blog as-studypeach@tumblr.com. Any problems, feel free to get in touch via my messages.