Chemistry Key Terms

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ionic bond

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An ionic bond is a type of chemical bond that involves a metal and a non-metal ion (or polyatomic ions such as ammonium) through electrostatic attraction. In short, it is a bond formed by the attraction between two oppositely charged ions.

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coordinate covalent bond

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A coordinate covalent bond (formerly also known as dative bond[1]) is a description of covalent bonding between two atoms in which both electrons shared in the bond come from the same atom.

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covalent bond

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A covalent bond is a form of chemical bonding that is characterized by the sharing of pairs of electrons between atoms, or between atoms and other covalent bonds. In short, attraction-to-repulsion stability that forms between atoms when they share electrons is known as covalent bonding.[1]

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hydrogen bond

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A hydrogen bond is the attractive force between one electronegative atom and a hydrogen covalently bonded to another electronegative atom. It results from a dipole-dipole force with a hydrogen atom bonded to nitrogen, oxygen or fluorine (thus the name "hydrogen bond", which must not be confused with a covalent bond to hydrogen).

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unshared pair of electrons

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An unshared electron pair, also known as a nonbonding pair of electrons or as a lone pair of electrons, is two electrons in the same orbital in the outer shell of an atom that are not used in the formation of a covalent bond.

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vander der waal forces

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In physical chemistry, the van der Waals force (or van der Waals interaction), named after Dutch scientist Johannes Diderik van der Waals, is the attractive or repulsive force between molecules (or between parts of the same molecule) other than those due to covalent bonds or to the electrostatic interaction of ions with one another or with neutral molecules.[1] The term includes:

* permanent dipole–permanent dipole forces
* permanent dipole–induced dipole forces
* instantaneous induced dipole-induced dipole (London dispersion forces).

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acid

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An acid (from the Latin acidus meaning sour) is traditionally considered any chemical compound that, when dissolved in water, gives a solution with a hydrogen ion activity greater than in pure water, i.e. a pH less than 7.0.

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base

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In chemistry, a base is most commonly thought of as an aqueous substance that can accept hydrogen ions. A base is also often referred to as an alkali if OH− ions are involved. This refers to the Brønsted-Lowry theory of acids and bases. Alternate definitions of bases include electron pair donors (Lewis), as sources of hydroxide anions (Arrhenius). In addition to this, bases can commonly be thought of as any chemical compound that, when dissolved in water, gives a solution with a pH higher than 7.0.

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polyatomic ion

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A polyatomic ion, also known as a molecular ion, is a charged species (ion) composed of two or more atoms covalently bonded or of a metal complex that can be considered as acting as a single unit in the context of acid and base chemistry or in the formation of salts. The prefix poly- means many in Greek, but even ions of two atoms are commonly referred to as polyatomic.

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anion

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An ion is an atom or molecule where the total number of electrons is not equal to the total number of protons, giving it a net positive or negative electrical charge.

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cation

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Conversely, if there are more protons than electrons, the atom or molecule will be positively charged. This is called a cation (pronounced /ˈkætaɪən/; cat-eye-on), from the Greek κατά (kata), meaning 'down'.

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molecule

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In chemistry, a molecule is defined as a sufficiently stable, electrically neutral group of at least two atoms in a definite arrangement held together by very strong (covalent) chemical bonds.[1][2]

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polar molecule

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In chemistry, polarity refers to the dipole–dipole intermolecular forces between the slightly positively-charged end of one molecule to the negative end of another or the same molecule. Molecular polarity is dependent on the difference in electronegativity between atoms in a compound and the asymmetry of the compound's structure.

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molar mass

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the mass of one mole of a substance (chemical element or chemical compound).[2] It is a physical property which is characteristic of each pure substance. The base SI unit for mass is the kilogram[1] but, for both practical and historical reasons, molar masses are almost always quoted in grams per mole (g/mol or g mol–1), especially in chemistry.

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representative particle

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A representative particle is thought of as the smallest unit into which a substance may be divided without changing its composition. Some examples might be helpful. For a given chemical element, it's an atom. An atom of carbon is the smallest unit of carbon one can find. For a compound, it's a molecule. An atom of sodium and one of chlorine make up a molecule of sodium chloride (NaCl or table salt)

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avogadro's number

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6.022 141 79(30) × 1023

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STP

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the current version of IUPAC's standard is a temperature of 0 °C (273.15 K, 32 °F) and an absolute pressure of 100 kPa (14.504 psi)[1]

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structural formula

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The structural formula of a chemical compound is a graphical representation of the molecular structure showing how the atoms are arranged. The chemical bonding within the molecule is also shown, either explicitly or implicitly. There are three common representations used in publications, condensed, Lewis type and line-angle formulæ.

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electron dot structure

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Lewis structures, also called Lewis-dot diagrams, Electron-dot diagrams or Electron-dot structures, are diagrams that show the bonding between atoms of a molecule, and the lone pairs of electrons that may exist in the molecule.[1][2] A Lewis structure can be drawn for any covalently-bonded molecule, as well as coordination compoundsThey are similar to electron dot diagrams in that the valence electrons in lone pairs are represented as dots, but they also contain lines to represent shared pairs in a chemical bond (single, double, triple, etc.).

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product

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A product is a substance that forms as a result of a biological- or chemical reaction.

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reactant

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A reagent or reactant is a substance or compound consumed during a chemical reaction.[1] Solvents and catalysts, although they are involved in the reaction, are usually not referred to as reactants.

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catalyst

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Catalysis is the process in which the rate of a chemical reaction is either increased or decreased by means of a chemical substance known as a catalyst. Unlike other reagents that participate in the chemical reaction, a catalyst is not consumed by the reaction itself. The catalyst may participate in multiple chemical transformations. Catalysts that speed the reaction are called positive catalysts. Catalysts that slow down the reaction are called negative catalysts or inhibitors.

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balanced equation

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An equation for a chemical reaction in which the number of atoms for each element in the reaction and the total charge are the same for both the reactants and the products. In other words, the mass and the charge are balanced on both sides of the reaction.

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skeleton equation

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A skeleton equation is an equation that identifies the reactants and products in a chemical reaction by their chemical formula but does not quantify them.

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chemical equation

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A chemical equation may be described as a chemical reaction[1] or a means of writing out and describing such a phenomenon. The coefficients next to the symbols and formulae of entities are the absolute values of the stoichiometric numbers. The first chemical equation was diagrammed by Jean Beguin in 1615.

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percent yield

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In chemistry, yield, also referred to as chemical yield and reaction yield, is the amount of product obtained in a chemical reaction.[1] The absolute yield can be given as the weight in grams or in moles (molar yield). The fractional yield or relative yield or Percentage yield , which serve to measure the effectiveness of a synthetic procedure, is calculated by dividing the amount of the obtained product in moles by the theoretical yield in moles:
fractional yield} = {actual yield}over {theoretical yield}

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theoretical yield

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The fractional yield or relative yield or Percentage yield , which serve to measure the effectiveness of a synthetic procedure, is calculated by dividing the amount of the obtained product in moles by the theoretical yield in moles:

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actual yield

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%yield = (actual / theoretical ) x 100

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stoichiometry

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Stoichiometry (sometimes called reaction stoichiometry to distinguish it from composition stoichiometry) is the calculation of quantitative (measurable) relationships of the reactants and products in a balanced chemical reaction (chemicals). It can be used to calculate quantities such as the amount of products that can be produced with the given reactants and percent yield.

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absolute zero

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Absolute zero is a temperature marked by a 0 entropy configuration. It is the coldest temperature theoretically possible and cannot be reached by artificial or natural means. Temperature is an entropically defined quantity that effectively determines the number of thermodynamically accessible states of a system within an energy range. Absolute zero physically possesses quantum mechanical zero-point energy.

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vaporization

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Vaporization of an element or compound is a phase transition from the liquid phase to gas phase. There are two types of vaporization: evaporation and boiling.

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sublimation

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Sublimation of an element or compound is a transition from the solid to gas phase with no intermediate liquid stage. Sublimation is an endothermic phase transition that occurs at temperatures and pressures below the triple point (see phase diagram). At normal pressures, most chemical compounds and elements possess three different states at different temperatures.

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barometer

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A barometer is an instrument used to measure atmospheric pressure. It can measure the pressure exerted by the atmosphere by using water, air, or mercury. Pressure tendency can forecast short term changes in the weather. Numerous measurements of air pressure are used within surface weather analysis to help find surface troughs, high pressure systems, and frontal boundaries.

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kinetic theory

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Kinetic theory (or kinetic theory of gases) attempts to explain macroscopic properties of gases, such as pressure, temperature, or volume, by considering their molecular composition and motion. Essentially, the theory posits that pressure is due not to static repulsion between molecules, as was Isaac Newton's conjecture, but due to collisions between molecules moving at different velocities.

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SI units

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The International System of Units (abbreviated SI from the French Le Système International d'Unités[1]) is the modern form of the metric system and is generally a system devised around the convenience of the number ten. It is the world's most widely used system of measurement, both in everyday commerce and in science.[2][3]

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boyle's law

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Boyle's law (sometimes referred to as the Boyle-Mariotte law) is one of several gas laws and a special case of the ideal gas law. Boyle's law describes the inversely proportional relationship between the absolute pressure and volume of a gas, if the temperature is kept constant within a closed system.[1][2]

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charles' law

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Charles's law (also known as the law of volumes) is an experimental gas law which describes how gases tend to expand when heated. It

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gay-lussac's law

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The expression Gay-Lussac's law is used for each of the two relationships named after the French chemist Joseph Louis Gay-Lussac and which concern the properties of gases, though it is more usually applied to his law of combining volumes, the first listed here. One law relates to volumes before and after a chemical reaction while the other concerns the pressure and temperature relationship for a sample of gas.

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combined gas law

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The combined gas law is a gas law which combines Charles's law, Boyle's law, and Gay-Lussac's law. These laws each relate one thermodynamic variable to another mathematically while holding everything else constant. Charles' law states that volume and temperature are directly proportional to each other as long as pressure is held constant. Boyle's law asserts that pressure and volume are inversely proportional to each other at fixed temperature. Finally, Gay-Lussac's law introduces a direct proportionality between temperature and pressure as long as it is at a constant volume. The inter-dependence of these variables is shown in the combined gas law, which clearly states that:
“ The ratio between the pressure-volume product and the temperature of a system remains constant. "

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ideal gas law

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The Ideal gas law is the equation of state of a hypothetical ideal gas. It is a good approximation to the behaviour of many gases under many conditions, although it has several limitations. It was first stated by Émile Clapeyron in 1834 as a combination of Boyle's law and Charles's law.[1] It can also be derived from kinetic theory, as was achieved (apparently independently) by August Krönig in 1856[2] and Rudolf Clausius in 1857.[3]

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half-life

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The half-life of a quantity whose value decreases with time is the interval required for the quantity to decay to half of its initial value. The concept originated in describing how long it takes atoms to undergo radioactive decay but also applies in a wide variety of other situations.

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beta particlehttp://www.flashcardexchange.com/mycards/add/821421

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Beta particles are high-energy, high-speed electrons or positrons emitted by certain types of radioactive nuclei such as potassium-40. The beta particles emitted are a form of ionizing radiation also known as beta rays. The production of beta particles is termed beta decay. They are designated by the Greek letter beta (β). There are two forms of beta decay, β− and β+, which respectively give rise to the electron and the positron.

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alpha particle

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Alpha particles (named after and denoted by the first letter in the Greek alphabet, α) consist of two protons and two neutrons bound together into a particle identical to a helium nucleus; hence, it can be written as He2+ or 42He2+. They are a highly ionizing form of particle radiation, and have low penetration.They also have a total of Zero spin.

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gamma ray

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Gamma rays (denoted as γ) are electromagnetic radiation of high energy. They are produced by sub-atomic particle interactions, such as electron-positron annihilation, neutral pion decay, radioactive decay, fusion, fission or inverse Compton scattering in astrophysical processes. Gamma rays typically have frequencies above 1019 Hz and therefore energies above 100 keV and wavelength less than 10 picometers, often smaller than an atom. Paul Villard, a French chemist and physicist, discovered Gamma radiation in 1900, while studying uranium.

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fission

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In nuclear physics and nuclear chemistry, nuclear fission is a nuclear reaction in which the nucleus of an atom splits into smaller parts, often producing free neutrons and lighter nuclei, which may eventually produce photons (in the form of gamma rays). Fission of heavy elements is an exothermic reaction which can release large amounts of energy both as electromagnetic radiation and as kinetic energy of the fragments (heating the bulk material where fission takes place). Fission is a form of nuclear transmutation because the resulting fragments are not the same element as the original atom.

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fusion

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clear fusion is a reaction whereby two smaller nuclei are combined to form a larger nucleus. It results in the release of energy for reactions that form nuclei of mass number below 60, with the largest energy release occurring with the lightest nuclides. This stands in contrast to the process of nuclear fission in which a heavy nucleus is split into two smaller nuclei with the release of energy. Since light nuclei have smaller repulsion energies (the energy required to bring two like charges together), fusion is much more likely to occur among these nuclei.

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radiation

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In physics, radiation describes any process in which energy emitted by one body travels through a medium or through space, ultimately to be absorbed by another body. Non-physicists often associate the word with ionizing radiation (e.g., as occurring in nuclear weapons, nuclear reactors, and radioactive substances), but it can also refer to electromagnetic radiation (i.e., radio waves, infrared light, visible light, ultraviolet light, and X-rays) which can also be ionizing radiation, to acoustic radiation, or to other more obscure processes.

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solute

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In chemistry, a solution is a homogeneous mixture composed of two or more substances. In such a mixture, a solute is dissolved in another substance, known as a solvent. Gases may dissolve in liquids, for example, carbon dioxide or oxygen in water. Liquids may dissolve in other liquids. Gases can combine with other gases to form mixtures, rather than solutions.[1]

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solution

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In chemistry, a solution is a homogeneous mixture composed of two or more substances. In such a mixture, a solute is dissolved in another substance, known as a solvent. Gases may dissolve in liquids, for example, carbon dioxide or oxygen in water. Liquids may dissolve in other liquids. Gases can combine with other gases to form mixtures, rather than solutions.[1]

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suspension

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In chemistry, a suspension is a heterogeneous fluid containing solid particles that are sufficiently large for sedimentation. Usually they must be larger than 1 micrometre.[1] The internal phase (solid) is dispersed throughout the external phase (fluid) through mechanical agitation, with the use of certain excipients or suspending agents. Unlike colloids, suspensions will eventually settle. An example of a suspension would be sand in water. The suspended particles are visible under a microscope and will settle over time if left undisturbed. This distinguishes a suspension from a colloid in which the suspended particles are smaller and do not settle.[2] Colloids and suspensions are different from a solution, in which the dissolved substance (solute) does not exist as a solid and solvent and solute two are homogeneously mixed.

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emulsion

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An emulsion (IPA: /ɪˈmʌlʃən/[1]) is a mixture of two or more immiscible (unblendable) liquids. One liquid (the dispersed phase) is dispersed in the other (the continuous phase). Many emulsions are oil/water emulsions, with dietary fats being one common type of oil encountered in everyday life. Examples of emulsions include butter and margarine, milk and cream, and vinaigrettes; the photo-sensitive side of photographic film, magmas and cutting fluid for metal working. In butter and margarine, fat surrounds droplets of water (a water-in-oil emulsion). In milk and cream, water surrounds droplets of fat (an oil-in-water emulsion). In certain types of magma, globules of liquid NiFe may be dispersed within a continuous phase of liquid silicates. Emulsification is the process by which emulsions are prepared.

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molarity

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n chemistry, molar concentration (also called molarity, amount concentration or substance concentration) is a measure of the concentration of a solute in a solution, or of any molecular, ionic, or atomic species in a given volume. However, in thermodynamics the use of molar concentration is often not very convenient, because the volume of most solutions slightly depends on temperature due to thermal expansion. This problem is usually resolved by introducing temperature correction factors, or by using a temperature-independent measure of concentration such as molality.[1]

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supersaturated solution

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The term supersaturation refers to a solution that contains more of the dissolved material than could be dissolved by the solvent under normal circumstances. It can also refer to a vapor of a compound that has a higher (partial) pressure than the vapor pressure of that compound.

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concentration

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In chemistry, concentration is the measure of how much of a given substance there is mixed with another substance. This can apply to any sort of chemical mixture, but most frequently the concept is limited to homogeneous solutions, where it refers to the amount of solute in the solvent.

To concentrate a solution, one must add more solute, or reduce the amount of solvent (for instance, by selective evaporation). By contrast, to dilute a solution, one must add more solvent, or reduce the amount of solute.

Unless two substances are fully miscible there exists a concentration at which no further solute will dissolve in a solution. At this point, the solution is said to be saturated. If additional solute is added to a saturated solution, it will not dissolve (except in certain circumstances, when supersaturation may occur). Instead, phase separation will occur, leading to either coexisting phases or a suspension. The point of saturation depends on many variables such as ambient temperature and the precise chemical nature of the solvent and solute.

Analytical concentration includes all the forms of that substance in the solution.

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diluted solution

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in diluted solution ,proportion of solute is lesser than solvent.and in concentrated solution ,proportion of solute is larger than that of solvent.