Online Chemistry Notes for Students
Anupama Sapkota 
Polar Molecules Definition A polar molecule is a chemical substance in which the distribution of electrons between the atoms involved is uneven, resulting in a dipole moment. The term polarity is used to describe the difference in electrical poles of a molecule which then determines how polar the molecule is. The determination of whether or … Read more
Physical Change Definition A physical change is a process that changes the physical form of a substance but not its chemical composition. During a physical change, the molecules of a substance are rearranged, but the chemical composition of the substance remains unchanged. A physical change usually involves a change in physical properties like the change … Read more
Oxidation Definition Oxidation is a chemical process involving the loss of electrons by a molecule, atom, or ion, which increases the oxidation state of the chemical species. The historical definition of oxidation was based on the addition of oxygen to a compound as oxygen gas was the first known oxidizing agent. This definition aligns with … Read more
Organic Compounds Definition Organic compounds are chemical compounds composed of one or more carbon atoms bonded to other elements like hydrogen, oxygen, or nitrogen. Organic compounds consist of multiple carbon-hydrogen and carbon-carbon bonds that hold the structures together. Organic compounds are the result of the catenation property of carbon atoms as they can form chains … Read more
Definition of Lewis Acids and Bases Gilbert Newton Lewis (American, 1923) put forward a broader concept of acids and bases on the basis of electron transfer. This concept is called the Lewis concept. Lewis’s concept eliminates the necessity of the presence of hydrogen in acid, and it accepts not only Arrhenius and Bronsted-Lowry concept but … Read more
Differences between Acid and Base Image Source: Pinterest Basis Acid Base Arrhenius concept An acid is a substance that produces hydrogen ion (H+) as the only positive ion when mixed with water. A base is a substance that produces hydroxyl ion (OH–) as the only negative ion when mixed with water. Bronsted-Lowry Concept An acid … Read more
Nuclear Fission Definition Nuclear fission is a type of nuclear reaction or a radioactive decay process where the nucleus of a heavy atom divides into two or more roughly equal nuclei. Nuclear fission might occur spontaneously or might be induced by the excitation of the nucleus. Nuclear fission results in the release of a large … Read more
Nitrate Definition Nitrate is a nitrogen oxoanion formed by the loss of hydrogen from nitric acid with a charge of -1, one nitrogen atom, and three oxygen atoms. It is a polyatomic ion with the molecular formula NO3– that is commonly used in the form of salts in fertilizers and explosives. Nitrate is a monovalent … Read more
Natural Polymers Definition Natural polymers are natural substances composed of large macromolecules formed by the binding of small molecules called monomers. Natural polymers occur in the form of chemical compounds in biological systems and can be broadly categorized into three groups; polysaccharides, polyamides, and polynucleotides. Polymers are not restricted to monomers of the same chemical … Read more
Molecules Definition A molecule is a group of two or more atoms of the same or different atoms that represent the smallest identifiable unit of a substance that has the composition and chemical properties of the substance. Molecules are individual units of a pure substance or a compound that interact with each other to provide … Read more