A-Z Chemistry definitions for use with A-Level Chemistry

Our database of chemistry definitions provides key information and a summary of many chemistry terms, covering them in enough detail to help you fully understand the terms in preparation for your A-Level Chemistry exams.

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Allosteric Enzymes

Facts, Summary & Definition Allosteric enzymes are enzymes which have an additional site for an effector to bind to, as well as the active site Efforts regulate the activity of the enzyme – they can either activate or inhibit Allosteric enzymes are larger and more complex than normal enzymes They are regulated through homotropic regulation ...

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Chemical & Electron Affinity

Facts, Summary & Definition Affinity is the tendency of a chemical species to react with another species to form a chemical compound Chemical affinity depends on both stereochemistry and electrostatic interactions Electron affinity is the amount of energy released or spent when an electron in added to a neutral atom Drug affinity is how well ...

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Adducts

Facts, Summary & Definition An adduct is a product formed by an addition reaction Adducts can only be formed from reactants which have multiple bonds, such as alkenes and carbonyl groups Adducts can be formed through two types of addition reaction: electrophilic and nucleophilic Adducts often form between Lewis acids and Lewis bases What is ...

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Acids

Facts, Summary & Definition The Brønsted-Lowry theory defines an acid as a proton donor Compounds which can act as both an acid and a base are called amphiprotic The strength of an acid is measured using the pH scale The Lewis theory defined an acid as an electron pair acceptor Strong acids completely dissociate in ...

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Acidity

Facts, Summary & Definition The Brønsted-Lowry theory is the most common theory of acidity Acidity is measured using the pH scale The pH of a solution can be measured by using an indicator or a pH meter Acids act as proton donors, and bases act as proton acceptors You can calculate the proton concentration if ...

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Acid-Base Buffers

Facts, Summary & Definition Acid-base buffers can resist pH changes, but not completely stop them They are formed of a conjugate acid-base pair They are important for reactions which require a specific pH range You can calculate the pH of a buffer solution if you know the amount of acid used, the amount of base ...

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Accuracy

Facts, Summary & Definition Accuracy is a measurement of how close a measured value is to the true value Precision is a measurement of how close two or more measurements are to each other Accuracy and precision are not the same! What is accuracy? In science, accuracy refers to how close the measured value is ...

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Absorption of Light

Facts, Summary & Definition Light absorption is the process in which light is absorbed and converted into energy When electrons absorb energy, they become ‘excited’ and move to higher energy levels which are further away from the nucleus Electrons don’t like being in an excited state, and so fall back to their original energy level ...

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