Category: Chemistry Notes PPT

Halogenation is the term which can be defined as a chemical reaction that involves the addition of either one or more halogens either to material or compound. The halogenation’s stoichiometry and pathway depend on the functional groups and structural features of the organic substrate and the specific halogen. Also, inorganic compounds like metals undergo halogenation.

What is Halogenation of Alkanes?

Halogenation of an alkane produces a hydrocarbon derivative, where either one or more halogen atoms have been substituted for the hydrogen atoms.

Usually, alkanes are unreactive compounds only because they are non-polar and lack the functional groups, where the reactions can occur. Therefore, free-radical halogenation provides a method by which alkanes are functionalized.

However, a severe limitation of radical halogenation is the count of similar C-H bonds, present in all but the simplest alkanes, so the selective reactions are difficult to achieve.

General Reaction of Alkanes

Alkane halogenation is given as an example of a substitution reaction, which is a type of reaction that often takes place in organic chemistry. A substitution reaction is a chemical reaction, where a part of a small reacting molecule replaces either an atom or the atom’s group on a hydrocarbon or its derivative.

 

The general equation substituting a single halogen atom for one of the hydrogen atoms of an alkane can be given as follows.

 

 

General Features of Halogenation of Alkanes

The features of halogenation of alkanes can be listed as follows:

• The R-H notation is the alkane’s general formula. In this case, ‘R’ represents an alkyl group. At the same time, the addition of a hydrogen atom to an alkyl group forms the alkyl group’s parent hydrocarbon.

• The R-X notation on the product side can be represented as the general formula for a halogenated alkane, where, in this case, ‘X’ is the general symbol for a halogen atom.

• The reaction conditions can be noted by placing these conditions on the equation arrow, which separates the reactants from products. Halogenation of an alkane needs the presence of light or heat.

 

Chlorination of Methane by Substitution

In the halogenation of an alkane, the alkane is stated to undergo either chlorination, fluorination, iodination, or bromination, depending on the identity of the halogen reactant. Bromination and Chlorination are the alkane halogenation reactions that are used widely. In general, the fluorination reactions proceed too quickly to be useful, whereas iodination reactions go too slowly.

 

The halogenation of an alkene appears to be a simple substitution reaction, in which a C-H bond is broken and a new C-X bond is formed, which is unlike the complex transformation of combustion. A simple example of this reaction of chlorination of Methane has been shown below: 

CH4 + Cl2 + Energy → CH3Cl + HCl

The general equation substituting a single halogen atom for one of the hydrogen atoms of an alkane can be given as follows.

Mechanism of Halogenation of Alkanes

1. Initiation Step- The Cl-Cl bond of the elemental chlorine undergoes hemolysis when irradiated with UV light. This process yields two chlorine atoms, which are also called chlorine radicals.

 

 

2. Propagation Step- One of the chlorine radicals abstracts a hydrogen atom from methane to form the methyl radical. In turn, the methyl radical abstracts a chlorine atom from one of the chlorine molecules, and then, the formation of chloromethane takes place. Also, the second step of the propagation regenerates a chlorine atom, and these steps repeat several times until the termination happens.

 

 

3. Termination Step- The termination happens when a chlorine atom either reacts with the other chlorine atom to generate Cl2, or a chlorine atom reacts with a methyl radical to produce chloromethane, which constitutes a minor pathway, where the product is made. Also, two methyl radicals can combine to form ethane, which is a minor by-product of this reaction.

 

 

At this step, this reaction does not stop. However, the chlorinated methane product can be allowed to react with additional chlorine to form polychlorinated products.

 

 

By controlling the reaction conditions, including the ratio of chlorine to methane, it can be possible to favour the formation of either one or another possible chlorinated methane product.

 

Organic Compounds Halogenation

Halogenation by Reaction Type

There exist many pathways to halogenate organic compounds, like ketone halogenation, free radical halogenation, electrophilic halogenation, and the halogen addition reaction. These enzymatic halogenation reactions on the organic molecule are also popular, which either follow electrophilic, nucleophilic, or free radical mechanisms. The structure substrate is one factor, which determines the pathway.

 

Halogenation Reactions (Substitution Type)

Alkenes can react with halogens to form alkyl halides (or haloalkanes) in the presence of heat or light , which is called as a substitution reaction, because on the alkenes structure, the halogen atom is taking the place of or is substituting  one of the hydrogen atoms.

The reaction between fluorine and alkenes: This is an explosive reaction even in the dark and cold as you tend to get hydrogen and carbon fluoride produced instead of the desired substitution reaction. The reaction can be very dangerous as it does not yield the desired product and this also has no particular interest to organic chemists.

For example, the desired product is:

CH4   +   F2   →   CH3F   +   HF

But this is the result as the reaction goes so fast:

CH4   +   2F2   →   C   +   4HF

The reaction between iodine and alkenes: Under normal lab conditions, iodine does not react with alkenes to any extent. So this reaction is also not useful.

The reactions between bromine and chlorine with alkenes: The reaction will produce the desired alkyl halides in the presence of heat and light, but there is no reaction in the dark. So we shall focus our discussion on the  halogenation reactions with bromine and chlorine.

Hydrogen atom in the Methane is replaced by a chlorine atom in the substitution reaction. Until all the hydrogens are replaced, this reaction can happen multiple times. Ultimately, more hydrogens in the alkene are replaced as long as the reaction proceeds. Thus, we end up with a mixture of chloromethane(CH3Cl), dichloromethane(CH2Cl2), trichloromethane(CHCl3), and tetrachloromethane (CCl4).

The original mixture of a green gas( Cl2) And a colourless gas(CH4)  would produce a mist  of organic liquids (mixture of the chlorinated methane) and steamy fumes of hydrogen chloride(HCl). Except for chloromethane(CH3Cl) all the other organic products are liquid at room temperature. 

Halogenation by the Halogen Type

The halogen influences the halogenation facility. Chlorine and Fluorine are more electrophilic and also aggressive halogenating agents. In comparison, bromine is a weaker halogenating agent compared to both chlorine and fluorine. At the same time, iodine can be given as the least reactive of them all. The dehydrohalogenation facility follows the reverse trend, where the iodine can be removed most easily from organic compounds, and the organofluorine compounds are highly stable.

 

Nature of the Mechanism of Alkanes’ Halogenation

In the presence of either heat or ultraviolet light (UV), the halogen reaction with an alkane results in a haloalkane formation (which is an alkyl halide). This phenomenon can be explained using the reaction mechanism – A mechanism to halogenate. In the methane molecule, the carbon‐hydrogen bonds are the low-polarity covalent bonds.

 

Did You Know?

Electrophiles, which attach to the double bond of alkenes, weaken the ÿ bond. In contrast to the alkene hydrogenation, catalysts do not allow adding chlorine or molecular bromine to generate nearby dichalcogenides.

Hematite is an ore of iron. It is a dark red rock from which we get iron. It has a red or brown colour with an earthy lustre. It is a heavy and usually hard oxide mineral that constitutes the most important iron ore. It is derived from the Greek word “blood” in allusion to its red colour. 

It is the most important iron ore in the world. It is the most abundant minerals on Earth’s surface and in the shallow crust. It is a rock type of mineral found in sedimentary rocks and igneous rocks. 

Hematite can also occur as a result of volcanic activity. It is paramagnetic in nature. The crystals of hematite which have a steel grey colour and metallic lustre are known as specular iron ore. The scaly ore which is thin is known as micaceous hematite. It has opaque transparency and uneven fractures. Hematite is harder than pure iron ore.

In your daily life, you will find the use of iron in one way or another around yourself from small products to larger ones. It is one of the most important and widely used minerals on the Earth which has huge economic importance. Because of its hardness and strength, it is used for various purposes and by different iron and steel industries. Iron ore is extracted from the Earth and it is found in different kinds of iron ores and here, we will be talking about one of the important iron ores of the finest quality ie. Haematite. This topic will be beneficial for you while studying Geography, Earth Science or Chemistry etc. 

Hematite Ore

The elements are natural substances. Iron is also an element. It is a kind of metal. The most common chemical element on the Earth by mass and it is used widely. This metal is strong and hard and also used by manufacturing industries at larger because of its great strength and hardness whereas it also has magnetic properties. It has a great economic importance that we can not imagine the development of the economy without it. It is basically found in four major types i.e. Magnetite, Hematite, Limonite and Siderite. 

These types have different percentage of metallic iron in them. The first one has around 72% of iron and is black in colour which is considered as the best quality iron whereas the hematite ore contains 60 to 70% iron, red & brown and also considered as the finest quality. Hematite ore also contains a small amount of silica. It is in pure form and rapidly corrodes on exposure to moist air and high temperature.  

If we talk about the third and fourth ones i.e., Limonite and Siderite, they are considered as low-grade iron ore where the former is yellow in colour and contains 30 to 40% of iron whereas the latter has the most impurities with 48% iron and brown in colour.

Haematite Properties

The various properties of iron ore of hematite are mentioned below:

• The physical properties of this mineral describe it as metallic grey or red in colour, having a streak of bright red to dark red whereas lustre of metallic to splendent. Its diaphaneity describes it as opaque whereas it has a Mohd hardness of 6.5 and specific gravity of 5.26 whereas its density is 5.26 g / cm³ (Measured) and 5.255 g / cm³ (Calculated). Besides these, it is a brittle, irregular or uneven, trigonal mineral where its diagnostic properties say it is magnetic after heating.

• The optical properties of this mineral are that it is a type of Anisotropic with the colour varying from brownish red to yellowish-red whereas its penetration twins at {0001} or {1010} at the composition plane. Besides these, its optic sign is Uniaxial, has very high relief and birefringence of δ = 0.280. 

Hematite Uses

Let’s have a look at hematite uses:

• It is one of the finest iron ores in the world and one of the most important pigment minerals as well.

• It is a dense and inexpensive material.

• It is also used for ballasts for ships.

• It is used as gemstones or in making jewellery as well.

• It can be used for its calming and protective properties.

• It is used as polishing compounds.

• Hematite is also kept in the homes because it gives great energy and the ability to get the mind to focus.

Distribution

This map shows the top countries that produce iron ore. Brazil and Australia were considered as the major producers but now China is leading the race and now is the world largest producer of iron ore followed by Brazil and Australia. Besides these, the majority of the iron ore can be found in the North American continent, United Kingdom, Russia, South Africa and India or Ukraine. The important regions of the distribution of iron ore in different continents are mentioned below:

• In Europe, the major countries where the fine quality of iron is found are Sweden, France, United Kingdom, Ukraine, Germany. 

• In North America, it is found in the USA and Canada which includes the regions of Lake Superior, Alabama State, Wright, Sept Isles regions, etc.

• In South America, Brazil is the most famous and known producer. Besides this, it can be found in some regions of Venezuela and Chile such as the Orinoco Valley and La Sarena region respectively.

• In Africa, the major areas are South Africa, Liberia, Algeria, Morocco and Tunisia. 

• Australia as a country is one of the leading producers of iron ore in the world which includes regions like Pilbara, Tailoring peak, Mt. Goldsworthy, Mt. Tom Price, Kalanooka region,  Mt. Newman, and besides these it is also found in Queensland, New South Wales and Tasmania.

• In Asia, the major regions include Russia, China and India. Besides these, the Philippines is also one of the regions where iron ore is found.

Conclusion

To conclude, we can say that hematite is the most important and one of the finest quality of iron ore in the world. It is harder than pure iron. It occurs from volcanoes. As such, the colour of this ore is red.

It is the most abundant minerals on the Earth surface. Hematite has a wide variety of other uses. It is used to make jewellery, polishing, for heavy media separation, to produce pigments and put in homes for positive energy. Besides these, it also has healing powers. On this page, we have covered comprehensively this mineral such as what is haematite, its various properties, hematite uses, distribution in the world, etc. This article will help you in covering one of the major and widely used minerals in the world and will increase your knowledge as well. 

With an Atomic Mass of 164.9303, the chemical element Ho (Holmium) is one of the rarest compounds on earth. Holmium proves excellences in terms of malleability and ductility. This is a white-coloured, silvery textured soft material that possesses unusual magnetic characteristics. From nuclear control reaction procedures to medical treatment options that are non-invasive to a patient, Holmium plays a key role in many real-time applications. Known for its high significance, let us learn about this element Ho, by understanding its properties, chemical nature, examples, and a few important applications. 

Important Details about What Holmium is

‘Per Teodor Cleve’ (1840-1905) was the 1st Swedish chemist, who discovered Holmium spectroscopically in 1879 when working with another earth metal ‘Erbium’. The name was assigned for his place of birth named Uppsala in Stockholm, Sweden. 

Holmium is one of the rarest elements found on earth and is categorized as lanthanides. The element Ho is located in the 67th position in the periodic table. This is a silver, shiny material but turns yellowish oxide (Ho2O3), during the process of oxidation or when heated directly. Being completely soluble in acids, Holmium gets affected due to the presence of oxygen and water. 

As we noted before, the element Holmium has unusual magnetic potential and it also records the highest magnetic moment ever, which is 10.6 µB for a naturally-derived chemical substance. 

Let us now quickly understand the physical and chemical properties of Holmium from the following.

Physical and Chemical Properties of the Element Ho

Firstly, here are the physical properties of Holmium.

• A key rarest element found on earth. But it is more common than silver and gold. 

• Soft and silvery in texture and appearance. 

• Is both malleable and ductile. 

• Amount of Ho available inside the crust of the earth is approximated to be 0.7 to 1.2 parts per million. But mined in a few countries such as India, the United States of America, Sri Lanka, China, Australia and Brazil, in reserves estimated to be around 400,000 tonnes.

• Hexagonal close-packed (hcp) is the crystal structure of Ho.

• Forms an alloy when combined with other metals.

• High temperature is proportional to its high reactivity.

• HOL-me-um is the pronunciation. 

• Holmium possesses unusual attractive properties along with electrical conductivity, and majorly seen at times of low-temperature conditions.  

• Gadolinite and Monazite are the rarest isotopes of Ho.

Now, we have Some Important Chemical Properties.

• [Xe] 4f11 6s2 is the Electronic Configuration of Ho.

• The atomic number is 67 and the atomic mass is 164.9303.

• Noted in the periodic table at Row 6.

• Present in the section of Lanthanides in the f-block of the periodic table. 

• Solid structure at 20°C celsius. 

• Somewhat electropositive. 

• Stability in room temperature. 

• Trivalently bonded.

• 1.23 is the Electronegativity as per the Pauling scale.

• 2,720°C (4,930°F) is the Boiling Point and Melting Point is 1,470°C (2,680°F).

• 8.803 grams is the Density of Ho per 1 Cubic Centimetre.

• Good desolvation in other acids, similar to other metals.

A gist about the Isotopes and Extraction of Holmium

An isotope is defined to be the more than 2 forms of a chemical element. For the element Ho, there is only 1 naturally-existing isotope which is holmium-165. Holmium-163 is a synthetic isotope with a half-life of 4570 years. 

There is a minimum count of 20 isotopes of Holmium that are found to be radioactive. However, there is no proven cases or enough scientific evidence about the health issues or safety measures for using Holmium to date. 

When there is a chemical ration between Holmium Fluoride (HoF3) and the Calcium metal, then this process gives rise to Holmium (Ho). 

The Significant Applications of Holmium

Even though the element is radioactive and there is no proven record for its toxicity (generally stated to be Low) there are enough applications for using Ho in industries and other research fields. Given below are some important applications of Holmium in real-life. 

• Holmium acts as a Flux concentrator to many high magnetic fields and also, this is used as an alloy in the production and manufacturing of magnets.

• The rods of nuclear control reactors make use of Holmium considering its good neutron absorption capacity. Moreover, the same absorption power of Ho makes it suitable for use as a burnable poison. 

• For Cubic Zirconia and Glass production, the Holmia also called the holmium oxide, is preferred for giving a natural yellow and red colouration. 

• To calibrate things, optical spectrophotometers prefer Holmium.

• The pole pieces of several static magnets make use of this powerful element Ho, owing to its high permeability. 

• For non-invasive medical processes, the element Ho is used in the case of solid-state specialized lasers for programs such as cancer treatment, fibre-optics, dental operations, and even for kidney stones.

• Holmium is majorly used in the treatment procedures of the eye disorder glaucoma, and even to correct failed or wrong glaucoma surgeries. Holmium lasers come handy for reducing the abnormal range of pressure in human eyes. 

• In the future, with enough research for its quantum property, one can utilize Holmium for quantum computers and other classical control methods. 

Conclusion 

Holmium (Ho) is a silver, rare earth metal, with the atomic number 67 and present in the 6th row, f-block of the periodic table. The element is categorized under the lanthanides. It has unusual electrical and magnetic properties and is used in nuclear reactors for its good absorption power. The reactivity of Ho is high at increased temperatures but usually stable at room temperature. Holmium-165 is the only naturally-occurring isotope but there are 20 radioactive isotopes noted for Ho. The toxicity of this element is still not known completely but there is a good number of applications for Holmium in the fields of medicine and dental procedures.

The crystalline chemical compound or the substances that contain a water molecule as a constituent of the compound is called hydrate. The water in these molecules combines chemically in a definite proportion. In hydrate compounds, the water molecules surround and interact with solute ions or molecules. The water molecules present in these compounds are called water of hydration. Some common example of hydrates are:

• Sodium hydrate.

• Copper hydrate.

• Calcium hydrate.

• Hydrates of carbon.

Hydration Process

The process of adding water to the compound is called hydration. This is the process in which water molecules surround and interact with solute ions or molecules. 

Water of Hydration

It is the form of water that is chemically combined with a compound to form a hydrated compound is called water of hydration. The water of hydration can be expelled from the compound by simple heating. The removal of water of hydration does not alter the composition of the substance essentially.

Such crystalline structures contain positive and negative ions. These ions are attached to the ionic bonds. The crystal lattice of these compounds contains water molecules. During the formation of the crystal lattice of these compounds, the water molecule gets traps in it. The presence of a water molecule in their crystal lattice is the main reason for the formation of such a special type of crystal structure. The mass of hydrated and dehydrated molecules will be different.

The mass of water of hydration molecule can find out by the formula:

Let the mass of the hydrated solid molecule = m₁

Let the mass of the dehydrated or anhydrous solid molecule = m₂

Mass of water molecule = m₁ – m₂

Hydrate Chemistry

When a polar compound is dissolved in water it gets split into two parts; cation and anion. The cation gets surrounded by the oxygen of the hydroxyl group (OH–) present in the water and the anion gets surrounded by the hydronium ion (H+) of the water molecule. 

Example: Copper Sulphate (CuSO4 . 5 H2O)

CuSO4 .5H2O → Cu+2 + SO4-2

In this compound, the copper ion and sulphate ions are surrounded by water molecules. Copper ions are surrounded by four water molecules and sulphate ions are surrounded by one water molecule. This difference is due to the nuclear charge. The nuclear charge on a copper ion is high (high nuclear charge) due to high charge density and the nuclear charge on sulphate ion is low (low nuclear charge) due to low charge density. The ion with more nuclear charge will combine more water molecules.

Different Types of a Hydrate

• Sodium hydrate.

• Calcium hydrate.

• Hydrates of carbon.

Sodium Hydrate-

Sodium hydrate is a hydrated form of the sodium ion. Its molecular formula is H₂ NaO⁺. The molecular weight is 41.00 g/mol. Its hydrogen bonding donor count is one. The formal charge of the sodium hydrate molecule is one. The structure of Sodium hydrate is given below:

Calcium Hydrate- 

Calcium hydrate is generally known as hydrated lime. Calcium hydrate is a hydrated form of calcium. The molecular weight is 92.11 g/mol. Its molecular formula is CaH4O3. The chemical name of calcium hydrate is calcium dihydroxide. Its hydrogen bond donor count is three. The formal charge of calcium hydrate is zero. The structure of calcium hydrate is given below:

Hydrates of Carbon- 

The hydrates of carbon are known as carbohydrates. These are the main source of energy. It is the first respiratory substrate in the human body. In hydrates of carbon, the ratio of hydrogen and oxygen is 2: 1. The generalized formula of the hydrates of carbon is Cx (H2O)y. Simple carbohydrates that are sweet are called sugar. Carbohydrates are the main source of energy in the body. In a normal man 55-65% of energy is available to him is in the form of carbohydrates present in his diet.

Types of Carbohydrates

Monosaccharides-

These are the simplest sugar that can not be further hydrolysed. In their generalised formula x is always equal to y. It means the number of carbon and oxygen atoms is the same. All monosaccharides occur in d and l form, except the dihydroxyacetone. Examples of monosaccharides are glucose, fructose, galactose, and mannose.

Oligosaccharides- 

Oligosaccharides are those carbohydrates that on hydrolysis yield 2 to 10 monosaccharide units. In this type of hydrate of carbon, monosaccharides are linked together by glycosidic linkage. Aldehyde or ketone group of one monosaccharide reacts with the alcoholic group of another monosaccharide to form a glycosidic bond. One molecule of water is eliminated during glycosidic bond formation.

Polysaccharides- 

These are composed of a large number of monosaccharides units. The suffix “an” is added in their names and they are known as glycans.

Did You Know?

The human brain is 95% water.

A person can lose a pint to a gallon of urine a day.

Do you know that water regulates the internal body temperature?

The water of hydration gives colour to the compound.

Moisture is a vaporized source of water.

Hydrogen is defined as the first element of the periodic table because its atomic number is 1, which means it contains only one single electron in its atom. Therefore only 1 electron is available in its outermost shell. The elements’ placement in the periodic table is according to their electronic configuration.

 

One of the smallest and the first element of the periodic table is hydrogen. This hydrogen element is widely used not only in industries but also in various daily life materials that are used. Hydrogen has a lot of properties that are similar to a lot of the elements in the periodic table. It is due to these similarities that are found that Hydrogen has a Position in The Periodic Table that is quite a different form above and is placed singly. With the wide number of properties, it is seen that Hydrogen is quite different from others while also showing a lot of similarities

Structure of Hydrogen

The structure of hydrogen is similar to that of alkali metals (ns1), which contains one electron in their outermost shell. Also, it can attain helium noble gas configuration by accepting an electron. This character is mostly the same as that of the halogen family (ns2, np5), and is also short of one electron for the completion of the electron octet in their shells.

 

When a hydrogen atom loses an electron and produces a cation, it resembles the alkali metals whereas, when it gains an electron and becomes a uni-negative ion, it represents similarity to the halogens. By taking a look at these properties, the position of hydrogen in the periodic table is the major question.

Hydrogen in the Periodic Table

Moving on to the formation of compounds, hydrogen produces oxides, sulphides, and halides resembling alkali metals. Whereas unlike the alkali metals, it contains a very high ionization enthalpy, and hence it lacks metallic characteristics under regular conditions. By looking in terms of the ionization enthalpy, it is found that hydrogen resembles more halogens compared to alkali metals. For example, ΔiH of lithium is given as 520 kJ mol-1, hydrogen is given as 1312 kJ mol-1, and for fluorine, it is given as 1680 kJ mol-1. It also exists as a diatomic molecule similar to that of halogens (for example, chlorine Cl2); a single hydrogen bond exists when the H2 molecule is formed.

 

Though hydrogen atoms exhibit a lot of resemblance to both alkali metals and halogens, both are very different. Thus, in the periodic table, great thought has to be given for the hydrogen position. When the hydrogen atom loses electrons, the size of its nucleus decreases and almost becomes 1.5 × 10-3 pm, which is much smaller when compared to the atomic sizes of the normal metals, and therefore the hydrogen ion does not freely exist in nature.

The Reason Behind Placing the Hydrogen Atom at First in the Periodic Table

Generally, in the periodic table, Hydrogen does not have a fixed position. In a few tables, it is placed with alkali metals (which is above Sodium), and in a few others, it is lonely placed at the top (Randomly, Just above the first Period).

 

Hydrogen resembles the alkali metals in electronic configuration. Hydrogen atoms contain the re-configuration 1s1, and it is the first element to be placed according to the rule. It is also placed with the alkali metals because it can lose its one e- to form H+ simply such as the alkali metals. Whereas hydrogen atoms also resemble halogens. Alkali metals produce hydrides such as LiH and Nah, just similar to LiCl and NaCl. The electrolysis of hydrides produces H2, and the Electrolysis of NaCl yields Cl2. In addition, hydrogen can gain one electron, such as halogens, to produce a noble gas configuration (which is H-).

 

Because of its resemblance to halogens and alkali metals, its position is still not fixed. But conventionally, we keep it including the alkali metals.

Why is Hydrogen Placed in Both Periodic Table Groups?

Hydrogen holds one valence electron in its outermost shell, and therefore it contains similar chemical properties compared to alkali metals. Also, hydrogen exists as a diatomic molecule similar to halogens and produces compounds with both metals and nonmetals. Thus, the hydrogen molecule can be placed in both the 1st as well as 17th groups in the modern periodic table. This anomaly with the position of hydrogen was one of the biggest demerits of Mendeleev’s periodic table.

 

However, considering the modern periodic table, the hydrogen molecule has been awarded the top position, which neither belongs to group 1 nor group 17.

Elements That Won’t Occur Naturally

Up to plutonium (having an atomic number of 94), all the periodic table elements are present on Earth, although many of them (namely promethium, technetium, polonium, francium, astatine, protactinium, plutonium, and neptunium) take place simply in tiny amounts, typically as the by-products of other’s radioactive decay. Their amounts are very tiny, up to a recent past, where those elements were given as not occurring naturally on Earth. As per the atomic numbers, which are higher than 94, all of the corresponding elements are artificial, and they do not occur naturally on Earth.

Importance of Hydrogen

The most important hydrogen in the human body function is to keep the body hydrated. Water contains oxygen and hydrogen and is absorbed by the cells of the body. Thus, it is defined as a crucial element that can be used as a military weapon, fuel, and more, but not in our bodies.

Facts About Hydrogen:

1. It has an atomic number of 1

2. It has the atomic symbol H

3. Hydrogen has an atomic weight of 1.0079

4. It has two oxidations states +1 and -1

5. The elemental classification of hydrogen is non-metal.

History of Hydrogen:

Hydrogen has descended from a Greek word named Hydro which means water and Gennaro which means production. This in short means water producer. It was first found and isolated by Cavendish in the year 1766 when hydrogen was believed to be a lot of different things. Cavendish who found the element himself thought that it was an inflammable air from metals which gave proof to the production of Hydrogen by the action of acids on metals. Before this happened Robert Boyle and Paracelsus had both used iron and acids to generate hydrogen gas and Antoine Lavoisier gave hydrogen its name because it used to produce water when it was ignited in the air.

The term ‘alcohol’ refers to organic compounds with one, two, or more hydroxyl groups (-OH), which are attached to the carbon atom (alkyl group or hydrocarbon chain).

A derivative of water is defined as alcohol in which one hydrogen atom is replaced by an alkyl group. Inorganic compounds, R represents the alkyl group. Alcohol can also be formed in different ways.

Among most organic compounds that occur commonly, alcohols account for a significant portion. Sweeteners and perfumes can be made using these materials, but they can also serve as catalysts for the creation of related compounds, and others can be found in various organic chemicals.

Types of Alcohol

There is a difference between alcohols depending on whether they contain hydroxyl groups. Alcohols also differ in their physical and chemical properties based on the location of the hydroxyl group.

Alcohol is divided into three types. There are three types of alcohol: primary, secondary, and tertiary alcohols.

An alkyl group is classified according to where its carbon atom is attached to the hydroxyl group. There are a number of alcohols that are described as colourless liquids or even solids at room temperature. Molecular weight means how soluble an alcohol is in water; the higher the molecular weight, the less soluble the alcohol and the greater the density, boiling point, vapor pressure, and viscosity.

Brief Overview of the Different types of Alcohol

Primary Alcohols

Primary alcohols are those alcohols in which only one alkyl group has a carbon atom attached to the hydroxyl group (OH). Methanol (propanol), ethanol, and others are examples of these primary alcohols. There is no relation between the complexity of an alkyl chain and whether it is considered primary or secondary. There is only one linkage between a –OH group and an alkyl group for any alcohol to qualify as a primary.

Secondary Alcohols

Typically, secondary alcohols have a carbon atom attached to the hydroxyl group and has two adjacent alkyl groups. There may be two structurally identical alkyl groups or even two different ones. Some examples of secondary alcohols are given below.

Tertiary Alcohols

An alcohol that contains a hydroxyl group attached to the carbon atom and connected to three alkyl groups is said to be a tertiary alcohol. These alcohols differ in their physical properties mainly because of their structure. It allows the alcohols to bind to their neighbouring atoms via hydrogen bonds through the -OH group. Alcohols’ boiling points are higher than their alkanes because of weak bonds formed between the molecules. Some examples of tertiary alcohols are-

Methods of Identifying Alcohol

1. Ferric Chloride Test

To determine whether an alcohol is aromatic or aliphatic, you can use iron (III) chloride. A reddish-orange color is created by the iron chloride compound. An aromatic alcohol, such as phenol, changes the coordination property of the central iron atom by replacing the chloride atoms with aromatic alcohol. The color changes from green to purple. In this case, the iron (III) chloride will not react with the amino alcohols, which is why the solution remains orange-red.

2. Schiff’s Reagent 

Schiff’s reagent, which is a fuchsia dye that is discolored when sulfur dioxide is passed through it, can be used to distinguish between primary and secondary alcohols. It becomes bright magenta in the presence of aldehyde, even in very small amounts. Because ketones react slowly with it to impart the same color, it must be used absolutely cold. A faster color change occurs with heat, but the competition between the ketone reactions makes it confusing. The vapors produced by Schiff’s reagent can be passed through this reaction mixture when heated in a bath of hot water.

• Aldehyde is formed when Schiff’s reagent turns magenta quickly.

• A simple trace of pink color or no color change in the Schiff’s reagent in a minute or so indicates that no aldehyde was formed, and no primary alcohol is present.

• A color change in an acidified potassium dichromate (VI) solution can be used to identify secondary alcohols.

3. Jones Test

As a powerful oxidizing agent, chromium trioxide is used in the Jones test to detect alcohol in the presence of sulfuric acid. A primary alcohol is converted into an aldehyde in the presence of Jones’ reagent. In turn, the carboxylic acid will be transformed into a ketone, while the secondary alcohol will be converted into a carboxylic acid. This test is based on the chromium oxidation state. The Jones’ reagent shows chrome to be in the oxidation state of +6. This reagent is bright reddish and orange due to the presence of Cr(VI) complexes.

The reaction process reduces chromium from Cr (VI) to Cr(III) at a reduced oxidation state of +3. To form the chromate ester, the chromic acid and the alcohol acid are combined. Following that, H2O forms the carbonyl group while the Cr(VI) is reduced to Cr(IV) thereby cleaving the C-H alcohol bond. Two electrons are removed from the Cr(IV) by reduction, and two electrons are removed from the carbon of the alcohol by oxidation. Hence, this is known as a reduction-oxidation step.

Also, Cr(IV) participates in the further oxidation steps, and it is eventually reduced to Cr(III). Often, Cr(III) is present as a Hexa aqua chromium (III) ions — [Cr(H2O)6]3+ – and Cr(III) complexes, whereas the H2O molecules are replaced either by one or more sulphate ions — [Cr(H2O)5(SO4)]+. All these complexes provide Cr(III), which is the characteristic green color.

The colour of the solution is not maintained by chromium reactivity with tertiary alcohols. Consequently, the Jones test helps differentiate between primary alcohols and secondary alcohols.

Uses of Alcohols

Alcohols can be used in many different ways. The following are a few examples.

• Drinking alcohol is the consumption of alcohols containing 30–40 percent by volume of ethanol.

• Antifreeze solutions are made by mixing ethylene glycol with water and using this solution as an antifreeze agent.

• The antiseptic agent ethanol is derived from alcohol.

• The internal combustion engines use some alcohols for fuel, like methanol.

• The good news is that some of them can be used as preservatives in laboratories to preserve specimens.

To summarize, this article focuses on the history of alcohol, types of alcohol, identification and uses of alcohol. For more information on this or any other chemistry topic, please visit .