Finally, P - T of the glossary. All the terms come from the glossary of this book. Remember, you can download the entire glossary from here.
P
Periodicity -
The regular recurrence of the properties of elements when they are arranged in atomic number order as in the Periodic Table.
Period -
A horizontal row of elements in the Periodic Table. There are trends in the properties of the elements as we cross a period.
Propagation -
One of the steps of a chain reaction in which a free radical converts reactant into product and another free radical is formed which can take part in another propagation step.
Proton -
A positively charged sub-atomic particle found in the nuclei of atoms.
R
Redox -
Short for reduction-oxidation, it describes reactions in which electrons are transferred from one species to another.
Reducing Agent -
A reagent that reduces (adds electron to) another species.
Reduction -
A reaction in which an atom or group of atoms gains electrons.
S
Shielded Nuclear Charge -
(also called effective nuclear charge). The positive charge from the nucleus that is felt by the outer electrons of an atom - it is the total number of positive charges on the nucleus of an atom minus the total number of inner electrons.
Specific Heat Capacity, c -
The amount of heat needed to raise the temperature of 1g of substance by 1K.
Spectator Ions -
Ions that are unchanged during a chemical reaction i.e. they take no part in the reaction.
Standard Molar Enthalpy Change of Combustion -
The amount of heat energy given out when 1 mole of a substance is completely burned in oxygen at standard conditions (298K and 100kPa).
Standard Molar Enthalpy Change of Formation -
The heat change when 1 mole of substance is formed from its elements at standard conditions (298K and 100kPa).
Stoichiometric -
Describes the simple whole number ratios in which chemical species react.
Strong Nuclear Force -
The force that holds protons and neutrons together whithin the nucleus of an atom.
T
Termination -
The stage of a chain reaction in which two free radicals combine together to give a species that is not a free radical.
Thermal Decomposition -
The breakdown of a compound by heat.
Thermochemical Cycle -
A sequence of chemical reactions (with their enthalpy changes) that convert a reactant into a product. The total enthalpy change of the sequence of reactions will be the same as that for the conversion of the reactant to the prduct directly (or by any other route).
Showing posts with label Chemistry. Show all posts
Showing posts with label Chemistry. Show all posts
Wednesday, January 14, 2009
Glossary Part 2
F - O of the Chemistry Glossary. All the terms come from the gloassary of this book. Remember, you can download the entire glossary from here.
F
Free Radical -
A reagent that has an unpaired electron.
G
General Formula -
The formula of a family of organic compounds expressed by using n to represent the number of carbon atoms.
Giant Molecular Structure -
An arrangment of atoms covalently bonded together in such a way that the structure extends indefinetely in 3 dimensions.
Giant Structure -
An arrangement of atoms or ions bonded together in such a way that the structure extends indefinetely in 3 dimensions.
Group -
A vertical column of elements in the Periodic Table. The elements have similar properties because they have the same outer electron arrangement.
Heterolysis -
Describes the breaking down of a covalent bond such that both the electrons in the bond go to one of the atoms and none to the other. The process results in the formation of a positive ion and a negative ion.
Homologous Series -
A set of organic compounds with the same functional group. The compounds differ in the length of their hydrocarbon chains.
Homolysis -
Describes the breaking of a covalent bond such that one of the electrons in the bond goes to one of the formation of a pair of free radicals.
I
Initiation -
The first step of a chain reactions in which a pair of free radicals is formed by bond homolysis.
Intermolecular Forces -
Forces that act between molecules and atoms that are not covalently bonded together (van der Waals forces, dipole-dipole forces and hydrogen bonding).
Ionic Bonding -
A type of bonding between metals and non-metals that is the result of the attraction between the positive metal ions and negative non-metal ions, formed from the transfer of electrons.
Ionisation Energy -
The energy required to remove a mole of electrons from a mole of isolated gaseous atoms.
Ions -
Atoms or molecules that have an overall electrical charge.
Isotopes -
Atoms of the same element (i.e. having the same number of protons) but having different numbers of neutrons.
K
Ketone -
An organic compound inwhich there is a C=O double bond.
L
Leaving Group -
In an organic substitution reaction, the leaving group is an atom or group of atoms that is ejected from the starting material, normally taking with it an electron pair and forming a negative ion.
Lone Pair -
A pair of electrons that is not involved in bonding, in the outer shell of an atom. Also called an unshared pair.
M
Mass Number (or Nucleon Number) -
The total number of neutrons and protons (nucleons) in the nucleus of an atom.
Maxwell-Boltzmann Distribution -
The distribution of energies (and therefore speeds) of the molecules in a gas or liquid.
Metallic Bonding -
A type of bonding found in metals in which positively charged metal ions are held together by their attraction to their pooled sea of outer electrons.
Molecular Formula -
A formula that tells us the numbers of atoms of different elements that make up a molecule of a compound.
Molecular Orbitals -
Volumes of space in which electrons may be found. They spread over two (or more) atoms.
Molecular Structure -
A compound that consists of small molecules.
Molecule -
A small group of atoms held together by covalent bonds.
Monomer -
A small molecule that combines with many other monomers to form a polymer.
N
Neutron -
An uncharged sub-atomic particle found in the nuclei of atoms.
Nucleons -
Protons and neutrons - the sub-atomic particles found in the nuclei of atoms.
Nucleophilic Substitution -
An organic reaction in which a molecule with a partially positively charged carbon atom is attacked by a reagent with a negative charge (a nucleophile). It results in the replacement of one of the groups or atoms on the orginal molecule by the nucleophile.
Nucleus -
The tiny, positively charged centre of an atom composed of protons and neutrons.
O
Orbital -
A volume of space in which an electron or pair of electrons may be found.
Oxidation -
A reaction in which an atom or group of atoms loses electrons.
Oxidation Number -
The number of electrons lost or gained by an atom in a compound compared to the uncombined atom. It forms the basis of a way of keeping track of redox (electron transfer) reactions.
Oxidation State -
An alternative term for oxidation number.
Oxidising Agent -
A reagent that oxidises (removes electron from) another species.
Oxidising Power -
The ability of a reagent to oxidise (remove electron from) another species.
F
Free Radical -
A reagent that has an unpaired electron.
G
General Formula -
The formula of a family of organic compounds expressed by using n to represent the number of carbon atoms.
Giant Molecular Structure -
An arrangment of atoms covalently bonded together in such a way that the structure extends indefinetely in 3 dimensions.
Giant Structure -
An arrangement of atoms or ions bonded together in such a way that the structure extends indefinetely in 3 dimensions.
Group -
A vertical column of elements in the Periodic Table. The elements have similar properties because they have the same outer electron arrangement.
Heterolysis -
Describes the breaking down of a covalent bond such that both the electrons in the bond go to one of the atoms and none to the other. The process results in the formation of a positive ion and a negative ion.
Homologous Series -
A set of organic compounds with the same functional group. The compounds differ in the length of their hydrocarbon chains.
Homolysis -
Describes the breaking of a covalent bond such that one of the electrons in the bond goes to one of the formation of a pair of free radicals.
I
Initiation -
The first step of a chain reactions in which a pair of free radicals is formed by bond homolysis.
Intermolecular Forces -
Forces that act between molecules and atoms that are not covalently bonded together (van der Waals forces, dipole-dipole forces and hydrogen bonding).
Ionic Bonding -
A type of bonding between metals and non-metals that is the result of the attraction between the positive metal ions and negative non-metal ions, formed from the transfer of electrons.
Ionisation Energy -
The energy required to remove a mole of electrons from a mole of isolated gaseous atoms.
Ions -
Atoms or molecules that have an overall electrical charge.
Isotopes -
Atoms of the same element (i.e. having the same number of protons) but having different numbers of neutrons.
K
Ketone -
An organic compound inwhich there is a C=O double bond.
L
Leaving Group -
In an organic substitution reaction, the leaving group is an atom or group of atoms that is ejected from the starting material, normally taking with it an electron pair and forming a negative ion.
Lone Pair -
A pair of electrons that is not involved in bonding, in the outer shell of an atom. Also called an unshared pair.
M
Mass Number (or Nucleon Number) -
The total number of neutrons and protons (nucleons) in the nucleus of an atom.
Maxwell-Boltzmann Distribution -
The distribution of energies (and therefore speeds) of the molecules in a gas or liquid.
Metallic Bonding -
A type of bonding found in metals in which positively charged metal ions are held together by their attraction to their pooled sea of outer electrons.
Molecular Formula -
A formula that tells us the numbers of atoms of different elements that make up a molecule of a compound.
Molecular Orbitals -
Volumes of space in which electrons may be found. They spread over two (or more) atoms.
Molecular Structure -
A compound that consists of small molecules.
Molecule -
A small group of atoms held together by covalent bonds.
Monomer -
A small molecule that combines with many other monomers to form a polymer.
N
Neutron -
An uncharged sub-atomic particle found in the nuclei of atoms.
Nucleons -
Protons and neutrons - the sub-atomic particles found in the nuclei of atoms.
Nucleophilic Substitution -
An organic reaction in which a molecule with a partially positively charged carbon atom is attacked by a reagent with a negative charge (a nucleophile). It results in the replacement of one of the groups or atoms on the orginal molecule by the nucleophile.
Nucleus -
The tiny, positively charged centre of an atom composed of protons and neutrons.
O
Orbital -
A volume of space in which an electron or pair of electrons may be found.
Oxidation -
A reaction in which an atom or group of atoms loses electrons.
Oxidation Number -
The number of electrons lost or gained by an atom in a compound compared to the uncombined atom. It forms the basis of a way of keeping track of redox (electron transfer) reactions.
Oxidation State -
An alternative term for oxidation number.
Oxidising Agent -
A reagent that oxidises (removes electron from) another species.
Oxidising Power -
The ability of a reagent to oxidise (remove electron from) another species.
Sunday, January 11, 2009
Glossary
A - E of a Chemistry Glossary. All the terms come from the gloassary of this book. You can download the entire glossary file from here.
A
Activation Energy -
The minimum energy that a particle needs in order to react: the energy (enthalpy) difference between the reactants and the transition state.
Aldehyde -
An organic compound with the general formula RCHO in which there is a C=O double bond.
Allotropes -
Pure elements which can exist in different physical forms in which their atoms are arranged differently. For example, diamond, graphite and buckminsterfullerene are allotropes of carbon.
Anions -
Negatively charged ions.
Atomic Number (Proton Number) -
The number of protons in the nucleus of an atom. Also the order of an element in the Periodic Table.
Average Bond Enthalpy -
The amount of enthalpy (energy) that has to be put in to break a specicfied chemical bond. It is an average value for the specified bond in a number of different compounds.
B
Biodegradeable -
A substances is biodegradeable if it breaks down naturally in the environment under the action of microorganisms, enzymes etc
C
Calorimeter -
An instrument for measuring the heat changes that accompany chemical reactions.
Carbanion -
An organic ion in which one of the carbon atoms has a negative charge.
Carbocation -
An organic ion in which one of the carbon atoms has a positive charge.
Carboxylic Acids -
Organic compounds with the general formula RCOOH in which there is a C=O double bond and an -OH group on the same carbon atom.
Catalytic Cracking -
The breaking, with the aid of a catalyst, of long-chain alkane molecules (obtained from crude oil) into shorter chain hydrocarbons, some of which are alkenes.
Cations -
Positively charged ions.
Chain Reaction -
A reaction with several steps involving free radicals.
Complex Ions -
Ions with more than one atom covalently bonded together.
Coordinate Bonding -
Covalnet bonding in which both the electrons in the bond come from one of the atoms in the bond (also called dative covalent bonding).
Cracking -
The breaking of long-chain alkane molecules (obtained from crude oil) into shorter chain hydrocarbons, some of which are alkenes.
Covalent Bonding -
A type of bonding between non-metal atoms that is the result of electrons being shared between the atoms.
D
Dative Covalent Bonding -
Covalent bonding in which both the electrons in the bond come from one of the atoms in the bond (also called coordinate bonding).
Disproportionation -
Describes a redox reaction in which the oxidation number of some atoms of a particular element increases and that of other atomsof the same element decreases.
E
Electron -
A negatively charged sub-atomic particle that is found at some distance from the nucleas of an atoms.
Electron Pair Repulsion Theory -
A theory which explains the shapes of simple molecules by assuming that groups of electrons around a central atom repel each other and thus take up positions as far away as posible from each other in space.
Electronegativity -
The ability of an atom to attract the electrons in covalent bonds towards itself.
Electrophile -
A reagent that attacks electron-rich areas in an organic molecule (such as carbon-carbon double bond).
Electrostatic Forces -
The forces of attraction and repulsion between electrically charged particles.
Elimination Reaction -
A reaction in which a small molecule such as water or hydrogen chloride is ejected from the reactants.
Empirical Formula -
The simplest whole number ratio in which the atoms in a compound combine together.
Endothermic -
Describes a reaction in which heat is taken in as the reactants change to products - the temperature thus drops.
Energy Density -
Describes the amount of energy stored per kilogram by a fuel. This energy can be released by burning the fuel.
Enthalpy Diagrams -
Diagrams in which the enthalpies (energies) of the reactants and products of a chemical reaction are plotted on a vertical scale to show their relative levels.
Entity -
The simplest forumla unit of a compound.
Exothermic -
Describes a reaction in which heat is given out as the reactants change to products - the temperature thus rises.
A
Activation Energy -
The minimum energy that a particle needs in order to react: the energy (enthalpy) difference between the reactants and the transition state.
Aldehyde -
An organic compound with the general formula RCHO in which there is a C=O double bond.
Allotropes -
Pure elements which can exist in different physical forms in which their atoms are arranged differently. For example, diamond, graphite and buckminsterfullerene are allotropes of carbon.
Anions -
Negatively charged ions.
Atomic Number (Proton Number) -
The number of protons in the nucleus of an atom. Also the order of an element in the Periodic Table.
Average Bond Enthalpy -
The amount of enthalpy (energy) that has to be put in to break a specicfied chemical bond. It is an average value for the specified bond in a number of different compounds.
B
Biodegradeable -
A substances is biodegradeable if it breaks down naturally in the environment under the action of microorganisms, enzymes etc
C
Calorimeter -
An instrument for measuring the heat changes that accompany chemical reactions.
Carbanion -
An organic ion in which one of the carbon atoms has a negative charge.
Carbocation -
An organic ion in which one of the carbon atoms has a positive charge.
Carboxylic Acids -
Organic compounds with the general formula RCOOH in which there is a C=O double bond and an -OH group on the same carbon atom.
Catalytic Cracking -
The breaking, with the aid of a catalyst, of long-chain alkane molecules (obtained from crude oil) into shorter chain hydrocarbons, some of which are alkenes.
Cations -
Positively charged ions.
Chain Reaction -
A reaction with several steps involving free radicals.
Complex Ions -
Ions with more than one atom covalently bonded together.
Coordinate Bonding -
Covalnet bonding in which both the electrons in the bond come from one of the atoms in the bond (also called dative covalent bonding).
Cracking -
The breaking of long-chain alkane molecules (obtained from crude oil) into shorter chain hydrocarbons, some of which are alkenes.
Covalent Bonding -
A type of bonding between non-metal atoms that is the result of electrons being shared between the atoms.
D
Dative Covalent Bonding -
Covalent bonding in which both the electrons in the bond come from one of the atoms in the bond (also called coordinate bonding).
Disproportionation -
Describes a redox reaction in which the oxidation number of some atoms of a particular element increases and that of other atomsof the same element decreases.
E
Electron -
A negatively charged sub-atomic particle that is found at some distance from the nucleas of an atoms.
Electron Pair Repulsion Theory -
A theory which explains the shapes of simple molecules by assuming that groups of electrons around a central atom repel each other and thus take up positions as far away as posible from each other in space.
Electronegativity -
The ability of an atom to attract the electrons in covalent bonds towards itself.
Electrophile -
A reagent that attacks electron-rich areas in an organic molecule (such as carbon-carbon double bond).
Electrostatic Forces -
The forces of attraction and repulsion between electrically charged particles.
Elimination Reaction -
A reaction in which a small molecule such as water or hydrogen chloride is ejected from the reactants.
Empirical Formula -
The simplest whole number ratio in which the atoms in a compound combine together.
Endothermic -
Describes a reaction in which heat is taken in as the reactants change to products - the temperature thus drops.
Energy Density -
Describes the amount of energy stored per kilogram by a fuel. This energy can be released by burning the fuel.
Enthalpy Diagrams -
Diagrams in which the enthalpies (energies) of the reactants and products of a chemical reaction are plotted on a vertical scale to show their relative levels.
Entity -
The simplest forumla unit of a compound.
Exothermic -
Describes a reaction in which heat is given out as the reactants change to products - the temperature thus rises.
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