D-Orbitals
D-orbitals are the five atomic orbitals with angular momentum quantum number l = 2, capable of holding up to 10 electrons. They appear starting from the third principal energy leve…
Chemical Glossary — Letter D
50 chemicals found starting with "D"
D-Transition Elements (Metals)
D-transition elements (also called transition metals or d-block elements) are elements in which the d orbitals are progressively filled. They occupy Groups 3–12 of the periodic tab…
Darmstadtium
Darmstadtium is a synthetic radioactive transactinide element named after Darmstadt, Germany. Expected to behave similarly to platinum. First synthesised in 1994 at GSI Darmstadt.
Daughter Nuclide
A daughter nuclide (or daughter isotope) is the nuclide produced as a result of the radioactive decay of a parent nuclide. After decay, the daughter nuclide may itself be radioacti…
Debye
The Debye (symbol: D) is a unit of electric dipole moment, named after physicist Peter Debye. It is used to express the magnitude of molecular dipole moments. One Debye equals 3.33…
Degenerate
In chemistry and quantum mechanics, degenerate refers to two or more quantum states (orbitals, energy levels) that have the same energy. For example, the three 2p orbitals (2px, 2p…
Delocalization
Delocalization in chemistry refers to the distribution of electrons (particularly π electrons or lone pairs) over more than two atoms in a molecule, rather than being localised bet…
Denaturation
The process by which a protein or nucleic acid loses its native three-dimensional structure due to disruption of stabilizing interactions. Denaturing agents include heat, extreme p…
Denatured
A term describing a substance, particularly a protein or nucleic acid, that has lost its native structure and function. Also refers to ethanol that has been rendered unfit for drin…
Density
The mass per unit volume of a substance, typically expressed in g/cm³ or kg/m³. Density is an intensive property that depends on temperature and pressure. It is calculated as densi…
Deposition
The phase transition in which a substance changes directly from a gas to a solid without passing through the liquid phase. This is the reverse of sublimation. Examples include fros…
Derivative
In chemistry, a compound that is structurally related to a parent compound and derived from it by chemical modification. For example, acetic acid is a derivative of ethane. Derivat…
Dermal Toxicity
The capacity of a substance to cause harmful effects when it contacts or penetrates the skin. Dermal toxicity assessments evaluate skin irritation, sensitization, and systemic toxi…
Designated Area
A specific location in a laboratory or workplace that has been formally assigned for particular activities, especially those involving hazardous materials. Designated areas have ap…
Detergent
A surfactant or mixture of surfactants with cleansing properties. Detergents contain both hydrophilic (water-loving) and hydrophobic (water-repelling) portions, allowing them to em…
Deuterium
A stable isotope of hydrogen with one proton and one neutron in its nucleus (symbol: ²H or D). It has approximately twice the mass of ordinary hydrogen. Heavy water (D₂O) contains …
Dextrorotatory
A term describing an optically active compound that rotates plane-polarized light in a clockwise direction (to the right) when viewed facing the oncoming light. Designated with a (…
Diagonal Similarities
The phenomenon in which certain elements in the periodic table show chemical similarities to the element diagonally adjacent to them in the next period. For example, lithium resemb…
Diamagnetism
A form of magnetism in which a material is weakly repelled by an external magnetic field. It arises from paired electrons whose magnetic moments cancel out. All substances have dia…
Differential Scanning Calorimetry (DSC)
A thermal analysis technique that measures the heat flow into or out of a sample as a function of temperature or time. DSC is used to study phase transitions, melting points, glass…
Differential Thermal Analysis (DTA)
A thermal analysis technique that measures the temperature difference between a sample and a reference material as both are heated or cooled at the same rate. DTA detects thermal e…
Differential Thermometer
A thermometer designed to measure small differences in temperature between two points rather than absolute temperatures. It is used in precise calorimetric measurements and thermal…
Dilution
The process of decreasing the concentration of a solute in a solution by adding more solvent. The dilution equation C₁V₁ = C₂V₂ relates initial and final concentrations and volumes…
Dimer
A molecule formed by the combination of two identical or similar monomer units. Dimers can be held together by covalent bonds or weaker intermolecular forces. For example, acetic a…
Dipole
A system consisting of two equal and opposite electric charges separated by a distance. In chemistry, a bond dipole arises when electrons are unequally shared between two atoms of …
Dipole Moment
A measure of the polarity of a molecule, defined as the product of the charge magnitude and the distance between the positive and negative charge centers. Expressed in Debye units …
Dipole-Dipole Interactions
Intermolecular attractive forces between polar molecules that arise from electrostatic interactions between permanent dipoles. The positive end of one molecule is attracted to the …
Dispersed Phase
In a colloid, the dispersed phase consists of small particles or droplets distributed throughout the continuous medium (dispersion medium). Examples include fat droplets in milk (d…
Dispersing Medium
The continuous phase of a colloid in which the dispersed phase particles are distributed. Also called the dispersion medium. For example, water is the dispersing medium in milk, an…
Displacement Reactions
Chemical reactions in which one element displaces another from a compound. Single displacement reactions occur when a more reactive element replaces a less reactive one. The activi…
Disproportionation Reactions
A redox reaction in which the same element is simultaneously oxidized and reduced, resulting in two different products. For example, copper(I) can disproportionate to copper(0) and…
Dissociation
The process by which a compound separates into ions or smaller molecules in solution or upon heating. Strong electrolytes completely dissociate in water, while weak electrolytes on…
Dissociation Constant
An equilibrium constant that quantifies the tendency of a complex or molecule to dissociate into its component parts. For acids, Ka represents the dissociation constant in water. L…
Distilland
The liquid mixture subjected to distillation from which a component is being separated. It is the starting material placed in the distillation flask. The distilland contains the le…
Distillate
The condensed liquid collected after the vapor has passed through the condenser during distillation. The distillate contains the more volatile components of the original mixture. P…
Distillation
A separation technique that exploits differences in volatility of components in a liquid mixture. The mixture is heated to vaporize the more volatile component, which is then conde…
Domain
In magnetism, a domain is a microscopic region within a ferromagnetic material in which all magnetic dipoles are aligned in the same direction. External magnetic fields cause domai…
Donor Atom
In coordination chemistry, the atom in a ligand that directly bonds to the central metal atom or ion by donating a lone pair of electrons. Common donor atoms include nitrogen, oxyg…
Dosimeter
A device used to measure an individual's accumulated exposure to ionizing radiation. Types include film badges, thermoluminescent dosimeters (TLDs), and electronic personal dosimet…
Double Bond
A covalent bond formed when two atoms share two pairs of electrons, consisting of one sigma bond and one pi bond. Double bonds are shorter and stronger than single bonds but allow …
Double Salt
A salt formed by the crystallization of two different simple salts in a fixed ratio from a common solution. Double salts dissociate completely in water to yield all the constituent…
Doublet
In spectroscopy, a doublet is a pair of closely spaced spectral lines arising from spin-orbit coupling or other splitting mechanisms. In NMR spectroscopy, a doublet occurs when a p…
Downs Cell
An industrial electrochemical cell used to produce sodium metal and chlorine gas by electrolysis of molten sodium chloride (NaCl). The cell operates at high temperatures (around 60…
DP Number
The DP (degree of polymerisation) number is the number of repeat units in a polymer chain. It determines the chain length and has a major influence on the physical properties of th…
Dry Cells
Electrochemical cells that use a paste or gel electrolyte rather than a liquid. The common zinc-carbon dry cell uses a zinc anode, manganese dioxide cathode, and ammonium chloride …
Dubnium
Dubnium is a synthetic radioactive transactinide element named after Dubna, Russia. It is expected to behave similarly to tantalum. First synthesised jointly by Soviet and American…
Dubnium
A synthetic radioactive transactinide element with atomic number 105 and symbol Db. It is named after Dubna, Russia, where it was first synthesized. Dubnium has no stable isotopes …
Dumas Method
A classical analytical technique for determining the nitrogen content of organic compounds. The sample is burned in excess oxygen, and the resulting nitrogen gas is measured volume…
Dynamic Equilibrium
A state in a reversible reaction where the forward and reverse reaction rates are equal, resulting in no net change in concentrations of reactants and products. At dynamic equilibr…
Dysprosium
Dysprosium is a silvery rare earth metal, atomic number 66. Second only to holmium in magnetic moment per atom. Critical component of high-performance NdFeB magnets where Dy additi…
About Chemicals Starting With D
This page lists all chemicals in our database beginning with the letter D. Each entry provides the chemical formula, CAS registry number, physical and chemical properties, common uses, and safety information. Use the alphabetical navigation above to browse other letters, or use the search function to find a specific chemical quickly.
Our chemical glossary covers acids, bases, salts, organic compounds, inorganic compounds, solvents, and many more categories. Click on any chemical name to view its full detailed profile.