Meaning of Chemistry in Science

Chemistry is the study guide of pure science that deals with the physical or chemical properties, reactions, composition, structure, and formula of matter formed by atoms, ions, or molecules and interacts with energy. Most of the chemistry articles we study are related to five basic branches such as physical, organic, inorganic, biochemistry, and analytical chemistry. The chemistry study guide also helps to describe the properties and structure of atoms of the periodic table elements. Therefore, it is a branch of science that studies chemical compounds formed from atoms, molecules, and ions by various chemical reactions.

Similarly, in the branch of biochemistry, we study various chemical and biological compounds such as carbohydrates, proteins, lipids, nucleic acids (DNA and RNA), vitamins and minerals, and many other essential compounds that are important for living organisms.

Learning chemistry suggests how new chemical compounds (inorganic or organic compounds) are formed from different types of atoms by chemical bonding such as ionic bonding, covalent bonding, or metallic bonding. Apart from these, chemistry also defines the behavior of matter found in our surroundings.

Branches of Chemistry

Physical, organic, inorganic, biochemistry, and analytical chemistry are the five basic branches of chemistry. Therefore, chemistry articles from these branches mostly help in systematic studying properties, composition, structure, and reactions of various classes of chemical and biological compounds that exist in our universe.

Apart from these primary branches, chemistry also has several specialized fields that deal with various matters. These specialized branches may include:

Medicinal Chemistry

Medicinal chemistry is a branch of chemistry that involves the identification, synthesis, and development of new chemical entities when they are suitable for therapeutic use.

Neurochemistry

Neurochemistry is also a branch of chemistry that studies the identities, structures, and functions of neurochemicals. Such neurochemicals generally control and influence the physiology of our nervous system.

Materials Chemistry

Materials chemistry is a part of materials science and engineering that generally investigates the chemical nature such as structure, properties, processing, and performance of materials.

Nuclear Chemistry

Nuclear Chemistry is the subfield of chemistry dealing generally with radioactivity, nuclear reactions (nuclear fission and nuclear fusion) that happen inside the nuclei of atoms.

Environmental Chemistry

Environmental chemistry is also a subfield of chemistry used for the scientific study of the chemical and biochemical phenomena that happen in natural places of our environment. It is used mostly for studying environmental pollution caused by various chemical substances.

Polymer chemistry

Polymer chemistry is a subfield of chemistry that focuses on studying structures, synthesis, and chemical and physical properties of polymers and macromolecules.

Thermochemistry

Thermochemistry is also a subfield of chemistry that studies heat and different types of energy changes or phase changes during any chemical reaction.

Green Chemistry

Green Chemistry is an area of chemistry and chemical engineering that focuses on the design of products and processes to minimize or eliminate the use and generation of hazardous substances.

Matter Definition in Science

Matter in science can be defined as anything that has mass, volume, or occupies space and is also felt by one or more sense organs. In our surroundings, we can see a large variety of objects with different shapes, sizes, and textures. Therefore, objects found on our earth and in the universe are called matter.

Altogether, what we see, taste, and smell is part of matter. Therefore, the oxygen we breathe, the food we eat, stones, clouds, stars, plants and animals, and even a particle in sand or a small drop of water−everything is a part of the matter.

In chemistry, depending on the chemical composition, matter is mostly classified into pure substances (elements, compounds) and mixtures. The substances found in our universe that contain only a single type of constituent particles are called pure substances.

Based on the nature of constituent particles, a pure substance is also of two types: elements and compounds.

List of Elements in Chemistry

An element in chemistry is a pure substance that contains a single type of atom characterized by a particular atomic number. Till today, 118 elements have been found in the periodic table.

Out of these 118 chemical elements, 92 are natural elements but 26 are artificial or man-made elements. On the basis of chemistry and chemical properties, these 118 elements are classified into three categories: metals, nonmetals, and metalloids.

Metals

Metals are the chemical elements that are solid, malleable, ductile, sonorous, and good conductors of heat and electricity. However, mercury is the only metal in the periodic table that is liquid at room temperature.

Nonmetals

Nonmetals are chemical elements that are neither malleable nor ductile and do not conduct heat or electricity. Generally, they are solids or gases but bromine is the only non-metallic element that exists in the liquid state at normal temperature and pressure.

Metalloids

Metalloids are also periodic table elements having intermediate properties between those of metals and non-metals. Examples of metalloids found on Earth are boron, silicon, germanium, etc.

Formula of Compound in Chemistry

A compound in chemistry defines a substance that contains two or more chemical elements chemically combined with one another in a fixed proportion. For example, water (H₂O), methane (CH₄), carbon dioxide (CO₂), sodium chloride (NaCl), and potassium chloride (KCl) are the most common compounds that we use widely in our daily lives.

These chemical compounds are broadly classified into two groups: inorganic and organic compounds. Organic compounds are hydrocarbons and their related compounds, while all the remaining compounds are called inorganic compounds.

Molecules

A molecule is the smallest part of a substance which capable of independent existence and shows all the properties of that substance. Molecules are generally formed when two or more atoms of the same or different elements bond together.

However, molecules of many elements may also be formed by a single atom of that element. For example, noble gases such as helium, neon, argon, etc.

According to the atomicity or number of atoms present in a molecule, they are classified into various types: monoatomic, diatomic, triatomic, tetratomic, and polyatomic.

• Monoatomic molecules: They consist of only one atom in their molecules. For example, helium (He), neon (Ne), argon (Ar), iron (Fe), aluminum (Al), etc.
• Diatomic molecules: They consist of two atoms in their molecules. For example, hydrogen (H₂), oxygen (O₂), nitrogen (N₂), bromine (Br₂), hydrochloric acid (HCl), carbon monoxide (CO), etc.
• Triatomic molecules: They consist of three atoms in their molecules. For example, ozone (O₃), carbon dioxide (CO₂), sulfur dioxide (SO₂), nitrogen dioxide (NO₂), hydrogen sulfide (H₂S), etc.
• Tetratomic molecules: They consist of four atoms in their molecules. For example, phosphorus (P₄), hydrogen peroxide (H₂O₂), etc.
• Polyatomic molecules: They consist of more than four atoms in their molecules. For example, methane (CH₄), octaatomic sulfur (S₈), etc.

Molecular Formula

In the study of chemistry, atoms of different elements are joined together in definite proportions to form molecules. For example, a water molecule is made up of hydrogen and oxygen in a ratio of 1:8 by mass or 2:1 by atom.

Empirical Formula Determination

The empirical formula in chemistry defines the relative number of each class of atom. Therefore, a general molecular formula helps in the calculation of composition or chemical structure of the molecule or compound.

Question: If 0.202 g of an organic compound gave combustion 0.361 g of carbon dioxide and 0.147 g of water. How to find the empirical formula of a compound in chemistry?

Answer: Weight of carbon in the said compound,
= (12/44) × 0.361 g
= 0.0985 g

Weight of the hydrogen
= (2/18) × 0.147 g
= 0.0163 g

Weight of oxygen,
= 0.202 − (0.0985 + 0.0163)
= 0.0872 g

Therefore, the ratio of the molar mass of carbon, hydrogen, and oxygen atoms,
C: H: O = (0.0985/12) : (0.0163/1) : (0.0872/16)
= 3: 5.98: 2

From the above solution, the empirical formula of said organic compound is C₃H₆O₂.

Molecular Weight Measurement

The methods used for the measurement of molecular weight are,

• Vapour density
• Elevation of boiling point
• Depression of freezing point

These methods are described fully in the physical chemistry textbooks. The other physical methods that are also used:

1. Graham’s law of diffusion
2. Sedimentation
3. The viscosity of liquids and gases
4. Osmotic pressure
5. X-ray radiation analysis
6. Mass or atomic spectrum (used for substances that contain high molar mass)

Atoms in Chemistry

Atoms are the smallest particles of an element which may or may not have independent existence but take part in a chemical reaction for the formation of molecules. For Example, atoms of hydrogen, oxygen, and nitrogen are not capable of carrying their independent existence. However, atoms of helium, neon, and argon exist independently.

An atom is the basic unit of chemistry or the basic building block of all matter. It consists of a dense core or positively charged nucleus surrounded by a space that is occupied by an electron cloud.

The nucleus of an atom contains positively charged protons and uncharged neutrons while the electron cloud contains negatively charged electrons revolving in discrete orbits around the nucleus.

An electron of an atom carries the key to the chemical world. Therefore, electronic configuration explains most of the chemical properties of an element. It generally explains electronegativity, ionization energy, preferred oxidation number, coordination number, and preferred types of chemical bonding (metallic, ionic, and covalent bonding).

Mixtures and Elements

A mixture is a collection of compounds constituted by more than one kind of pure substance. Most of the matter around us exists as a mixture of two or more pure chemical components. The most common examples of mixtures found around us are seawater, minerals, soil, etc.

Physical Chemistry

Physical chemistry is a branch of chemistry used for studying macroscopic and microscopic phenomena in chemical systems in terms of the principles, practices, and concepts of physics. Therefore, it is the physical and fundamental basis of chemical systems and processes which is important for studying various laws and concepts.

Physical Chemistry and Chemical Physics

Physical chemistry differs from other branches of science because it is employed for understanding chemical systems and reactions with the help of physics. The most common branches of physical chemistry are spectroscopy, quantum chemistry, chemical thermodynamics, and chemical kinetics.

Spectroscopy

Spectroscopy is a sub-branch of physical chemistry which used to study the interaction between matter and electromagnetic radiation. Therefore, hydrogen spectrum and various multi-electronic spectra are studied in this sub-branch of chemistry.

Quantum chemistry

Quantum chemistry is a subfield of physical chemistry that studies the application of quantum mechanics to solve chemical problems and determine the strength and shape of chemical bonds. It also specifies how a wavelength or frequency of light can be absorbed or emitted by a chemical compound.

Chemical thermodynamics

Chemical thermodynamics is used for studying the spontaneity of a chemical reaction and also the properties of chemical mixtures in terms of thermodynamics. Therefore, the conservation of energy principle, free energy, enthalpy, entropy, and activation energy are studied in this branch of chemistry.

Chemical kinetics

Chemical kinetics deals with the feasibility and rate of chemical reactions, and the effect of the rate of reaction due to changes in temperature, pressure, concentration of reactants, and chemical catalysts.

Physical Chemistry Topics

In physical chemistry, we study general definitions, laws, principles, mathematical equations, units and dimensions, or formulas related to chemical systems. The most common articles or topics studied in physical chemistry may include:

• States of matter: Solid, liquid, gaseous, and plasma states of matter
• Solid-state: Chemistry of crystalline solids and amorphous solids, etc.
• Gaseous state: Idea about ideal and real gas, critical temperature, pressure and volume, heat capacity of gases, Gas laws, Boyles Law, Charles Law, ideal gas law, Van der Waals equation, Graham’s law of diffusion and effusion, etc.
• Liquid state: Surface chemistry such as surface tension, density, surface energy, viscosity of liquids and gases, etc.
• Chemical equilibrium: Thermodynamics of chemical equilibrium, mass action law, Van’t Hoff equation, chemical catalyst, Le Chatelier Principle, etc.
• Chemical kinetics: Zero-order chemical kinetics, First-order chemical kinetics, etc.
• Spectroscopy: Electromagnetic spectrum, ultraviolet-visible spectroscopy, infrared spectroscopy, spectrophotometry, atomic absorption spectroscopy, atomic emission spectroscopy, microwave spectrum, electron spin resonance, etc.
• Quantum chemistry: Quantum mechanical concept of atoms and molecules.

The study of physical chemistry articles is incomplete if the student confines himself only to theoretical information. Therefore, they meed must gain practical explanations of the theory, definition, problem, and solution.

Inorganic Chemistry Study Guide

Inorganic chemistry is the study of the properties, composition, reactions, and formation of inorganic compounds by different types of atoms of chemical elements.

Therefore, inorganic chemistry is a broad field of science because it has many sub-branches. The most common sub-branches of such a field of chemistry may include:

• Coordination chemistry: It is a branch of science used for studying transition metal complexes.
• Bioinorganic chemistry: It is a specialized field of inorganic chemistry that focuses on the biochemistry of essential elements and compounds.
• Solid-state chemistry: This sub-discipline studies the synthesis and characteristics of solid materials.

In the inorganic chemistry study guide, we learn the properties of chemical elements or compounds that are closely related to their electronic configuration. Therefore, orbital hybridization, molecular orbital theory, and crystal field theory have given a clear understanding of modern inorganic compounds.

Inorganic Compound Meaning

Organic and inorganic compounds are two main classes of chemical compounds that are studied in chemistry. They can be differentiated by carbon−hydrogen bonds.

The organic molecules contain carbon-hydrogen bonds in their structure while inorganic compounds do not contain carbon-hydrogen bonds in their structure.

Inorganic compounds found on Earth are broadly categorized into four main categories: acids, bases, salts, and water.

Acids in Chemistry

According to Arrhenius’s definition, in the presence of an aqueous solution all acids give H⁺ ion or H₃O⁺ ion. In another definition, acids are electron acceptors and proton donors.

Mineral acids such as sulfuric acid (H₂SO₄), hydrochloric acid (HCl), and nitric acid (HNO₃) are common examples of inorganic acids used widely in various chemical processes.

Bases in Chemistry

They are the chemicals that neutralize acids by donating their electrons, releasing the hydroxide ions, or accepting protons. Such substances contain metals bonded with a hydroxyl group.

For example, potassium hydroxide, sodium hydroxide, calcium hydroxide, and magnesium hydroxide produce hydroxyl ions when they are dissolved in water.

Salts in Chemistry

Salts are characterized by their crystalline structure. They are produced by the neutralization reaction between an acid and a base. They are neutral, acidic, or basic in nature.

Therefore, the salts of strong acids and strong bases are neutral. However, the salts of strong acids and weak bases are acidic but weak acids and strong bases are basic in nature.

Water Molecule

Dihydrogen oxide or water is the most abundant and important inorganic substance that has the chemical formula H₂O. Such an essential part of living organisms forms during the combination of one oxygen atom and two hydrogen atoms.

Inorganic Compounds Examples

In our everyday life, we use a wide number of inorganic compounds in various fields of science (biology, chemical engineering, agriculture, medicine, electronics, etc). Examples and uses of such common inorganic compounds are:

• Borax: Used widely in the field of biochemistry and medicine.
• Boric acid: Borate ions obtained mostly from boric acid are used in biochemical and chemical laboratories to make buffer solutions.
• Urea: Used as a fertilizer to increase nitrogen content in soil.
• Zinc sulfate: Used widely in the field of medicine and agriculture.
• Heavy water: Used in spectroscopy, biochemistry, and as a neutron moderator in nuclear power reactors.
• Chlorine dioxide: Used in the chemical industry for bleaching, food processing, and water treatment.

Organic Chemistry

Organic chemistry is the study of properties, composition, and chemical reactions of organic compounds coming mainly from living organisms. Simply, it is the chemistry of carbon compounds.

The definition included compounds like carbon monoxide, carbon dioxide, carbonates, carbon disulfide, etc. However, these compounds are usually studied in inorganic textbooks. Therefore, it is the study of hydrocarbons and hydrocarbon-related compounds.

Organic Compounds

Organic compounds are substances that contain carbon atoms in their structure. Therefore, carbon atoms provide the key structural framework for generating such a vast number of organic molecules.

These compounds are key components of living organisms and organic biopolymers such as proteins, nucleic acids, and carbohydrates. Various classes of organic compounds are generally used for the comfort and health of humans. The most common examples of such types of chemical compounds are:

• Vital substances: hemoglobin, chlorophyll, enzymes, hormones, vitamins, etc.
• Clothing items: cotton, wool, silk, and synthetic fibers.
• Common fossil fuels: wood, coal, petroleum, and natural gas.
• Coatings items: varnishes, paints, lacquers, and enamels.
• Medicine: antibiotics, synthetic drugs, and pesticides.
• Natural and synthetic polymers: rubber and plastics.

Organic Chemistry Topics

Biochemistry Study Guide

Biochemistry is the scientific study of chemical substances and processes that occur in plants, animals, and microorganisms. Thus, various biochemical reactions help us to carry out every movement of life (from birth to death.

No other science subject has as much application as biochemistry or biological chemistry. Therefore, it applied many disciplines of science such as medicine, health, veterinary, agriculture, bioengineering, and biotechnology.

Advanced biochemistry tremendous impact on human welfare and has also largely benefited their living styles. Therefore, such a branch of chemistry is widely used in laboratories for disease diagnosis and the production of various therapeutic agents by genetic engineering and recombinant DNA technology.

Biological Molecule

Life is composed of lifeless chemicals and biomolecules or biological molecules. Therefore, a single cell of a bacterium has about 6,000 different types of biological molecules.

It is also believed that a man contains about 100,000 different types of biological molecules. Only a few of them are characterized and studied in the biochemistry subject.

Biochemistry is a sub-discipline of both chemistry and biology. Therefore, it is used mainly to study four types of biological molecules such as carbohydrates, proteins, fats, and nucleic acids.

• Carbohydrates: Monosaccharides are the monomeric units or building blocks of carbohydrates.
• Proteins: Amino acids are the monomeric units or basic building blocks of proteins.
• Fats or Lipids: It is the organic substances relatively insoluble in water but soluble in organic solvents and are potentially related to fatty acids utilized by living cells.
• Nucleic acids: Nucleotides are the monomeric units or basic building blocks of nucleic acids such as ribonucleic acid (RNA) and deoxyribonucleic acid (DNA).

Apart from these, nicotinamide adenine dinucleotide (NAD) and nicotinamide adenine dinucleotide phosphate (NADP) are also important biomolecules that participate in various metabolic processes. They act as electron carriers during various biological redox reactions.

Vitamins and Medicines

Analytical Chemistry

Analytical chemistry is the study or analysis of the chemical formula, structure, or composition of the atom, molecule, or matter for chemical, forensic, medicinal, food science, or technology.

However, modern analytical chemistry helps to identify general substances using various analytical instruments. Electrophoresis, capillary electrophoresis, chromatography, atomic absorption spectroscopy (AAS), optical fiber technology, and polarimetry are the most common instrumental methods used by an analytical chemist for their analysis.

Analytical Chemistry Methods

An analytical technique or method used mainly to determine the chemical or physical properties of chemical substances, elements, or mixtures obtained from organic and inorganic matter. The most useful analytical instruments used generally in modern technology and biotechnology are:

1. High Performance Liquid Chromatography (HPLC)
2. Gas Chromatography (GC)
3. Column Chromatography
4. Size Exclusion Chromatography (SEC)
5. Gel Permeation Chromatography (GPC)
6. Supercritical Fluid Chromatography (SFC)
7. Thin Layer Chromatography (TLC)
8. Ion exchange chromatography

There is a wide variety of classical and instrumental techniques used during the analysis of various substances in various fields of chemistry. The common techniques used for the analysis of various substances may include:

• Classical methods: It is a basic analytical method used generally in laboratories to determine the concentration of the analyte. The most common example of the classical method is the acid-base titration method.
• Spectrochemical analysis: It is a method of chemical analysis that depends upon the measurement of the wavelength and the intensity of the electromagnetic spectrum. Mass spectrometry (MS), atomic absorption spectroscopy (AAS), and atomic emission spectroscopy (AES) are generally used for the analysis of chemical and biological samples.
• Electroanalytical analysis: The three most useful sections of electroanalytical analysis that use the potential or current of an electrochemical cell are potentiometry, coulometry, and voltammetry.
• Chromatographic techniques: Chromatography in analytical chemistry is a laboratory technique used when separating chemical or biochemicals mixture into their components. Ion exchange chromatography is a useful and common purification technique used during the separation of molecules by ion exchange resin. Another chromatographic technique such as paper chromatography is generally used as a teaching tool in chemical laboratories.

Analytical Chemistry Course

The most challenging task for an analytical chemist is to explain what is the nature of the analytical chemistry course. It is an interdisciplinary branch of science where a large number of research works have contributed to its development.

Most chromatographic studies were invented by biochemists or biological scientists. Physicists may also discover various methods related to the electromagnetic spectrum and mass spectroscopy.

But if we look closely, different types of research topics publishes in different sets of science journals by using analytical chemistry methods. About 60% of such materials are published by persons who are not analytical chemists in the true sense.