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Atomic mass

An atomic mass is the mass of a single atom of a chemical element. It includes the masses of the 3 subatomic particles that make up an atom: protons, neutrons and electrons. Atomic mass can be expressed in grams. However, because each atom has a ...

                                               

Atomic number

The atomic number of an atom is the number of protons in the nucleus of the atom. The atomic number of an atom identifies which element it is. In a neutral atom, the atomic number is equal to the number of electrons orbiting the nucleus. The elem ...

                                               

Atomic theory

In chemistry and physics, the atomic theory explains how our understanding of the atom has changed over time. Atoms were once thought to be the smallest pieces of matter. However, it is now known that atoms are made up of protons, neutrons, and e ...

                                               

Avogadro constant

The Avogadro constant is the number of particles in one mole of a given substance. Its value is equal to 6.022 141 29 × 10 23 mol −1. The constant was named after the Italian scientist Amedeo Avogadro. The measurement of Avogadros constant was re ...

                                               

Bacteria bed

A bacteria bed is a layer of sand which is used to clean air or water from bacteria and other microorganisms. It is actually a type of filter. our beds are a hotbed for bacteria. The study, which had volunteers swab their unwashed sheets over a p ...

                                               

Base (chemistry)

A base is a substance that can accept a hydrogen ion from another substance. A chemical can accept a proton if it has a negative charge, or if the molecule has an electronegative atom like oxygen, nitrogen, or chlorine that is rich in electrons. ...

                                               

Belousov–Zhabotinsky reaction

The Belousov–Zhabotinsky reaction is an example of a chemical oscillator. It is often used to illustrate a chaotic system. The BZR is made of several chemical reactions, that occur in sequence. It shows chemical oscillation, which is unusual for ...

                                               

Beta particle

Beta particles are electrons or positrons emitted by some radioactive nuclei such as potassium-40 or carbon-14. The beta particles emitted are a form of ionizing radiation sometimes called beta rays. Henri Becquerel and Ernest Rutherford discover ...

                                               

Binary solution

A binary solution is a homogeneous mixture of two or more than two substances whose composition can change within a certain limits. The boiling point of binary solution depends upon the solution composition and there can be three cases: the boili ...

                                               

Biological hazard

A biological hazard, or biohazard, is anything coming from living organisms that could be a threat to someones health. It is represented by ☣, the biohazard symbol, which is used everywhere in the world. When people see this sign they know to tak ...

                                               

Carbocation

A carbocation is an ion with a positively-charged carbon atom. The charged carbon atom in a carbocation is a "sextet" Carbon atoms with eight valence elections have the maximum stability. Therefore, carbocations are often reactive, seeking to fil ...

                                               

Carburization

Carburization is the process by which carbon is introduced into a metal. It is done to make the surface harder and more abrasion resistant. Depending on the amount of time and temperature, the affected area can vary in carbon content. In earlier ...

                                               

CAS registry number

A CAS registry number is a unique number given to every chemical substance by the Chemical Abstracts Service. It is also called CASRN or CAS number. CAS registry number is also given to organic, inorganic compounds, minerals, isotopes, alloys. Th ...

                                               

Cathode ray

A cathode ray is a stream of electrons that are seen in vacuum tubes. It is called a "cathode ray" because the electrons are being emitted from the negative charged element in the vacuum tube called the cathode. A cathode ray tube aims the ray at ...

                                               

Chemical bond

Chemical bonds are what joins atoms together. Atoms bonded stay together unless the needed amount of energy is transferred to the bond. In general, strong chemical bonding comes with the sharing or transfer of electrons between the participating ...

                                               

Chemical change

A chemical change is a change of materials into other materials with different properties. Chemical changes occur when a substance combines with another to form a new substance, or, chemical decomposition into two or more different substances. Th ...

                                               

Chemical composition

Chemical composition is the arrangement, type, and ratio of atoms in molecules of chemical substances. Chemical composition varies when chemicals are added or subtracted from a substance, when the ratio of substances changes, or when other chemic ...

                                               

Chemical equation

A chemical equation is a way to predict the way that two or more chemicals will work together. Using what chemists know about the way chemicals act, we add the letter symbols together just like a math problem. In this way we can correctly guess i ...

                                               

Chemical formula

A chemical formula is a way that chemists describe a molecule. The formula says what atoms, and how many of each type, are in the molecule. Sometimes the formula shows how the atoms are linked, and sometimes the formula shows how the atoms are ar ...

                                               

Chemical property

In chemistry, a property is any aspect of a substance which is only seen by means of a chemical reaction. Simply speaking, chemical properties cannot be determined just by viewing or touching the substance. This is different from a physical prope ...

                                               

Chemical reaction

A chemical reaction happens when one or more chemicals are changed into one or more other chemicals. Examples: vinegar and baking soda combining to make sodium acetate, carbon dioxide and water many reactions that happen inside living things, suc ...

                                               

Chemical species

A chemical species is one of a group of atoms, molecules, molecular fragments, ions, etc., made to go through to a chemical process or to a measurement. Generally, a chemical species can be defined as an ensemble of chemically identical molecular ...

                                               

Chemical symbol

A chemical symbol is the shortform of the name of an element. Usually, it is made up of one or two letters, but sometimes it is made up of three letters. For example, the chemcial symbol for oxygen is O. The chemical symbol for calcium is Ca. Unt ...

                                               

Chemical synthesis

In chemistry, chemical synthesis means using chemical reactions to get a product, or several products. This happens by physical and chemical manipulations. Often, several different chemical reactions are used; one after another. In modern laborat ...

                                               

Chemically inert

In chemistry, the term inert is used to describe something that is not chemically active. The noble gases were described as being inert because they did not react with the other elements or themselves. Inert gases are completely inert to basic ch ...

                                               

Cheminformatics

Cheminformatics is the study of large amounts of chemical information. It is done mostly with the help of computers. These tools are used by pharmaceutical companies to discovery new drugs. Cheminformatics uses computer science and information te ...

                                               

Chitin

Chitin is a semitransparent material that is the main component of the exoskeletons of arthropods, such as crustaceans and insects, of the cell walls of fungi, the radula of molluscs and the beaks of cephalopods. Chitin has also proven useful for ...

                                               

Chromatography

Chromatography is a method using mixed substances that depends on the speed at which they move through special media, or chemical substances. It consists of a stationary phase and a mobile phase. The mobile phase flows through the stationary phas ...

                                               

Collective names of groups of like elements

There are areas on the periodic table where elements have similar properties. For example, all of the first column elements are light, very soft, react with water rapidly, make hydroxides that are strong bases, and react with the halogens to make ...

                                               

Combustion

Combustion is a reaction of a fuel with an oxidant to give out heat. The release of heat can produce light in the form of a flame. Car engines and rocket engines both work by combustion. Combustion in a Ferrari car motor is different from combust ...

                                               

Corrosion

Corrosion is the breakdown of materials due to chemical reactions. It is usually oxidation with air molecules and often in the presence of water. Corrosion also occurs when an acidic/basic material touches another material. When a material corrod ...

                                               

Crystal

A crystal is a solid whose molecules are arranged in a repeating pattern. Crystals are made from fluids by phase change. Usually the fluid is a liquid but snow is crystals precipitated from air. Crystallization can be by freezing from a simple fl ...

                                               

Crystal structure

In crystallography, the crystal structure is how the atoms are arranged in a crystalline material. Crystals occur naturally from the way the chemical bonds of the atoms connect. Symmetric repeating patterns occur in 3-D space in the crystal. The ...

                                               

Decaffeination

Decaffeination is a process which tries to remove most caffeine from things that contain it. Examples of plants that have caffeine in them are coffee beans, mate, tea leaves and cocoa. Soft drinks that do not have caffeine in them are sometimes c ...

                                               

Degree of unsaturation

Subtract the total from above from the number of hydrogens actually present. Determine the number of hydrogens that should be present if it was completely single bonded. In other words use the formula 2n+2 with n = the number of carbons present. ...

                                               

Dipole

Dipole can mean two things in physics. The first is an electric dipole which separates the positive charge from the negative charge. A simple example of this dipole is a pair of electric charges with the same magnitude but with the opposite type ...

                                               

Electrocyclic reaction

In organic chemistry, an electrocyclic reaction is a type of pericyclic rearrangement reaction. The reaction is electrocyclic if the result is one pi bond becoming one sigma bond or one sigma bond becoming a pi bond. Electrocyclic reactions share ...

                                               

Electrolysis

Electrolysis is a scientific way of splitting substances. Electrolysis means electric-splitting and involves the separation of substances through an electric current. Metals above carbon in the reactivity series are extracted by electrolysis.

                                               

Electron configuration

An electron configuration is the arrangement of electrons within an atom. The electron configuration describes where the electrons are inside orbitals. The structure of the Periodic table of elements is partly based on electron configuration. The ...

                                               

Electron shell

An electron shell, or main energy level, is the part of an atom where electrons are found orbiting the atoms nucleus. In chemistry and atomic physics, an electron shell may be thought of as an orbit followed by electrons around an atoms nucleus. ...

                                               

Electronegativity

Electronegativity, symbol χ, is a chemical property that says how well an atom can attract electrons towards itself. The electronegativity of an atom is influenced by the atoms atomic number and the distance between the atoms valence electrons an ...

                                               

Emulsion

An emulsion is what you get when you put two or more liquids together and the two liquids do not mix. Immiscible liquids do not mix together. For example, if you add oil to water, the oil floats on the surface of the water. And if you shake the t ...

                                               

Environmental chemistry

Environmental chemistry is the scientific study of the chemical and biochemical phenomena that occur in natural places. Environmental chemistry can be defined as the study of the sources, reactions, transport, effects, and fates of chemical speci ...

                                               

Equilibrium

An equilibrium is a state of a system where all forces acting on the system is balanced. A system that is in equilibrium does not change. The word has been used for different concepts from different fields of study. Thermal equilibrium means as m ...

                                               

Equilibrium constant

Equilibrium constant is a mathematical quantity which expresses the relationship between products and reactants of a reaction at equilibrium with respect to a specific unit. In other words, equilibrium constant is the reaction quotient of a chemi ...

                                               

Evaporation

Evaporation is when a liquid becomes a gas without forming bubbles inside the liquid volume. If bubbles are formed we are talking instead about "boiling". For example, water left in a bowl will slowly disappear. The water evaporates into water va ...

                                               

Exotic atom

An exotic atom is an atom that has a particle replaced by a particle of the same charge. For example, Positronium, an exotic atom, contains an electron and a positron. The positron replaces a proton which would normally be found in that atom. Mos ...

                                               

Extended periodic table

The extended periodic table is a version of the periodic table that is longer than the normal one. The inner transition metals are placed between Group 2 and Group 3 on the periodic table. On a normal periodic table the inner transition metals ar ...

                                               

Faradays laws of electrolysis

Faradays laws of electrolysis are a set of scientific laws used in chemistry. They are used to express magnitudes of electrolytic effects. They were first described by Michael Faraday in 1834. The first law states that the mass of a substance pro ...

                                               

Flotation

Flotation is a process where gas bubbles are injected at the bottom of a tank containing a mixture of a liquid and solid particles to separate the solid particles from the liquid. When the gas bubbles move along the liquid mixture, the solids par ...