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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Equilibrium Constant

Key Information & Summary Key Points Equilibrium Constant ( k c ) Reversible Reaction Dynamic Equilibrium Le Chatlier’s Principle Factors affecting Equilibrium Law of Mass Action Equilibrium constant of Pressure ( k p ) Types of Equilibrium constants Important Processes/ Reactions Bibliography Key points to remember: K c and k p are only affected by ...

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Elements

Key Information & Overview Definition Trends in the Periodic Table Common Reactions of different elements Entropy of Elements  Summary Elements are chemical substances which can not be broken down into simpler substances through chemical means. Each element contains one type of atom. An atom is the smallest part of an element that can take part ...

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Electrophoresis

Key Information & Overview: Definitions Hydrolysis of Proteins Structure of the Electrophoresis apparatus The Science behind Electrophoresis Reasons for the Changes in Speed Definitions Electrophoresis ​is a very common test run in labs which are used to identify and differentiate between different forms of protein. This process not only finds out which state the protein ...

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Electrons

Key Information & Summary Electrons are subatomic particles found in the shells around the nucleus in an atom There are four sub-shells. Sub-shell s has one orbital, p has three orbitals, d has five orbitals, and f has seven orbitals. The number of protons and electrons are equal in an atom but different in cation ...

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Electronegativity

Key Information & Overview: Definitions How does Electronegativity occur? Values and Trends of the Electronegativities of Atoms Electronegativity in Covalent Bonds Electronegativity in Ionic Bonds Bond Polarity Definitions Electronegativity ​of an atom is its ability to attract the electrons towards itself. Bond polarity​ is the unequal distribution of electrons in a covalent bond. The ​dipole​ ...

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Electrodes

Key Information & Summary: An electrode is an apparatus in which current travels through an object of substance Not all metals can conduct electricity in solid state Aqueous solutions are used in electrodes Electrodes are called half cells What are electrodes? Electrodes, also known as half cells, are used to find the Eθ of different ...

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Electrical Resistance

Key Information & Overview: Definitions How do Metals conduct Electricity? What is Electrical Resistance? What are the Factors affecting Electrical Resistance? How to measure Electrical Resistance in a Circuit Definitions Metallic Bonding​ is a bonding where positive ions are surrounding by a sea of delocalized electrons. Current ​is the rate of charge (or charged particles) ...

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Dilution

Key Information & Overview: Definitions What is dilution? Why Dilution is important? Dilution in Electrolysis Definition Dilution is the act of adding a solvent, usually water, to a solution. What is dilution? Dilution is when you add a solvent to a solution. In A level Chemistry, dilution only occurs with water. The amount of water ...

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Delocalisation

Key Points that will be discussed: Definition Examples in the course Effect of delocalized electrons on benzene Delocalisation energy Definitions Delocalisation of an electron occurs when the valence electron of an atom does not stay in its respective shell and starts to move around freely in valence shells of its covalently bonded molecule. Delocalisation energy ...

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Coulombic Attraction

Key Information & Overview Key points which are covered in this article: Key definition of what Coulombic attraction is Factors which affect the coulombic attraction Coulombic Attraction along the Period Definition Coulombic Attraction is the attraction between oppositely charged particles. Factors which affect the coulombic attraction Like, the South Pole of a magnet and the ...

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