DEFINITION
AN ACID
Arrhenius definition: An acid is a substance which
produces hydrogen ion (H+) as the only positive ion in
solution.
HCl → H+ + Cl-
H2O → H+ + OH-
Bronsted -Lowry’s definition: An acid is a proton
donor.
Lewis's acid: An acid is any species that accepts an
electron pair.
ACID-ANHYDRIDE: is the oxide of a nonmetal which
dissolves in water to yield the corresponding acid.
ABSOLUTE-ZERO-TEMPERATURE: This is the lowest
temperature in the Kelvin scale in which the volume of a gas is assumed to be
zero.
ACTINADES: The Period 7 elements that forms the
second inner transition series (5f block). It includes thorium (Th;Z=90) through lawrencium (Lr; Z=103)
ACTIVATED COMPLEX: It is the highest energy level in
a chemical reaction where the reactants are no longer reactants but are not yet
products.
ACTIVATION ENERGY: this is the minimum amount of
energy reactant particles must possess before a chemical reaction can
occur. OR it is the energy barrier that reactants must
overcome to become products
ACTIVITY: The change in number of nuclei (N) of a
radioactive sample divided by the change in time (t)
ALKANES: A hydrocarbon with the general molecular formular CnH2n+2. having only C-C single bonds
ALKENES: A hydrocarbon that contains at least
one carbon-carbon double bond (C=C bond)with the general formula CnH2n.
ALKYNES:
A hydrocarbon that contains at least one carbon-carbon triple bond (C=C
) with general formula CnH2n-2
ALLOTROPY: This is when an element occurs in
different form but in the same physical state.
ALLOTROPES: These are different forms of an
element occurring in the same physical state.
ALPHA (แผ) DECAY: A radioactive process in which
an alpha particle is emitted from the nucleus of a radioactive element.
ALPHA PARTICLE (แผ or 42He).
A positively charged particle, identical to a helium nucleus.
ANION: A negatively charged ion e.g Cl-,
O2-, N3- .
ANODE: The electrode at which oxidation occurs in an
electrochemical cell or an electrolytic cell.
ATOM: this is the smallest particle of an element
that can take part in a chemical reaction.
ATOMIC MASS: This is the sum of the protons and
neutrons in an atom of an element.
ATOMIC NUMBER: This is the number of protons in one atom an element.
BETA (ฮฒ) DECAY: This involves the emission of a
beta particle by a radioactive isotope.
BOILING POINT OF A LIQUID -: This is the temperature at which the saturated vapour pressure of the liquid is equal to the atmospheric pressure.
CATALYST: This is a substance that alters the rate of a chemical reaction, but itself is not affected by the reaction.
CARBOHYDRATES:- These are organic compounds that contain carbon, hydrogen and oxygen, where the hydrogen and oxygen are in the ratio of 2:1
CATHODE :- this is the electrode where reduction occurs in an electrochemical cell or an electrolytic cell.
CHEMICAL CHANGE: this is a change that is not easily reversible and in which a new substance is formed.
CONCENTRATION: this is the amount of a solute in
moles per dm3 of solution.
COMBINATION REACTION: This is when two or more
elements combine together to form a single compound example
Fe(s) + S(s) → FeS(s)
COVALENT BONDING: this is a type of bonding
that involves the sharing of electron pair between two atoms ( usually non-metals)
Cracking: this is the breaking down of higher
molecular mass alkanes to lower molecular mass alkanes and alkenes.
C10H22 → C8H18 + C2H4
DEGENERATE ORBITALS: These are orbitals that are
at the same energy level examples include the p-orbital, the d-orbital and the f-orbital.
EFFLORESCENCE: this is the phenomenon whereby some
salts when exposed to the atmosphere loses part or all of their water of
crystallization.
EFFLORECENT SALTS; these are salts which loses
part or all of their wate of crystallization when exposed to the
atmosphere.
ELECTRON AFFINITY: This is the energy evolved when an
electron enters an atom in the gaseous state to form a mole of gaseous negative
ions.
ELECTROLYSIS: - This is the decomposition of a compound brought about by the passage of a direct current through either a solution of the compound or its molten form
ELECTRONEGATIVITY: Is defined as the power of
an atom to attract (shared pair or bonded) electrons in a molecule.
ELECTROVALENT BOND: this is a type of bond that
involves the transfer of electrons from one atom (metal) to another
(non-metal). OR
it is the electrostatic force of attraction between
oppositely charged ions / cations and anions.
EMPIRICAL FORMULA: - This is the simplest formula of a compound; it shows the elements present and the ratio to which they are combined.
ENDOTHERMIC REACTION: This is a reaction during which heat is absorbed from the surrounding.
END POINT: This is the point at which the chemical reaction is complete during titration. The end point is detected with the help of an indicator.
ENTHALPY: This is the total heat content of a body/substance
ENTROPY:- This the degree of disorder or randomness of a system.
ESTERIFICATION REACTION: This is the reaction between an alkanoic acid and an alkanol to form an alkanoate (ester) and water only.
RCOOH + R'OH → RCOOR' + H2O
EXOTHERMIC REACTION: This is a reaction during which heat is
given off to the surrounding.
FERMENTATION:- This is the breakdown of carbohydrates into ethanol and carbon (IV) oxide by the action of micro-organism.
FUNCTIONAL GROUP: - A functional group may be a bond, an atom or a radical it is common to a homologous series and it also determines the chemical property of the series.
HALF-LIFE: - This is the time taken for half the total number of atoms in a given sample of a radioactive substance to undergo decay.
HOMOLOGOUS SERIES: - This is a family of organic compounds that have a regular structural pattern where successive members differs by a -CH2- group.
HYBRIDIZATION:- This is mixing of two or more orbitals to form a set of new and equal number of hybrid orbitals. the three most common types of hybridization are the sp3, the sp2 and the sp hybridization
HYGROSCOPY: This is a phenomenon whereby some substances when exposed to the atmosphere absorbs moisture and only become sticky or wet.
ION: This is a charged atom (particle) or group of atoms carrying a charged.
IONISATION ENERGY: - This is the
energy required to remove an electron from an atom to form a mole of gaseous
ions.
IONIC BOND: see electrovalent bond.
ISOMERS: these are organic compounds with the same
molecular formula but different structural formula.
ISOMERISM: This is the occurrence of two or more
organic compounds with the same molecular formula but different structural
formula.
ISOTOPES: These are atoms of the same element with
the same atomic number but different mass number.
ISOTOPY: This is the occurrence of atoms of the same element with the
same atomic number but different mass number.
MASS CONCENTRATION: This is the concentration expressed in g/dm3
MOLAR CONCENTRATION: This is the concentration expressed in mols/dm3
MOLAR MASS: - This is the mass of one mole of a substance.
the unit is g/mol.
MOLAR SOLUTION: These is a solution that contains one mole (1mol) or the molar mass of a substance in 1dm3 of solution
MOLECULAR FORMULA: -This is the actual formula of a compound; it shows the exact number of atoms present in one molecule of compound.
OXYDATION: This is the loss of electrons from a substance.
OXYDIXING AGENT: A substance that accepts/gains electrons.
PHYSICAL CHANGE: this is a change that is easily reversible
and in which no new substance is formed.
POLLUTION:- This is the release of harmful substances into the atmosphere in concentration that is harmful to man and his environment.
POLYMERIZATION: This is the process whereby two or more small molecules
(monomers) link together to form large molecules (polymer).
REDUCTION: This is the gain of electrons
REDUCING AGENT: A substance that donate/loss electrons
SATURATED SOLUTION: - This is a solution that contains as much solute particles as it can hold at a particular temperature in the presence of undissolved solute particles.
STANDARD SOLUTION: This is a solution with a known concentration.
SUPER SATURATED SOLUTION: - This is a solution that contains More than the solute it can normally hold a particular temperature.
SOLUBILITY: - Solubility of a solute in a solvent is the amount of solute in moles or grams that can saturate 1dm3 of solvent (water) at a particular temperature.
VULCANIZATION:- Vulcanization is a process whereby natural rubber is heated with sulphur under pressure in order to obtain a harder, tougher and more elastic rubber