Definitions Flashcards
Periodicity
Quality or character of being repeated at intervals
Valency
The number of electrons in the outer shell of an atom which are able to form bonds with other atoms
Molar mass
The mass in grams of one mole of that substance
Halide
Binary compound of a halogen with another element or group of elements
Oxide
An ion of oxygen
Molecular formula
Concise way of expressing information about the atoms that make up a particular covalent molecular compound. Gives the exact number of each type of atom in molecule
Empirical formula
Shows the simplest ratio of atoms in the compound
Physical change
A change that does not alter the chemical nature of the substance, no new chemical substances are formed
Chemical change
A change in which the chemical nature of the substances involved changes, new chemical substances are formed
Law of constant proportions
Sometimes called Proust’s law or the law of definite composition, states that a chemical compound contains exactly the same proportion of elements by mass
Law of conservation of mass
The total mass of a substance taking part in a chemical reaction is conserved during the reaction
Dissolving/ dissolution
Solid ionic crystals breaking up into ions in H2O
Dissociation
Process in which ionic compounds separate into smaller ions
Hydration
Where ions become surrounded with water in solution (no IMF- only the polarity of the water molecule and the charge of the ions)
Electrolytes
A substance that contains free ions and behaves as an electrically conductive medium
Precipitate
The solid that forms in solution during a chemical reaction
Precipitate reactions
Chemical reactions where solids form when two solutions of soluble salts react.
Ion exchange reaction
Reaction where the positive ion exchange their respective negative ions due to a driving force
Acid base reaction
Reaction in which an acid reacts with a base to form a salt and water
Mole
SI unit for amount of substance
Avogadro’s number
The number of particles in a mole of substance
Molar volume of gases
One mole of gas occupies 22,4 dm3 at standard temperature and pressure
Concentration
The amount of solute per unit volume of solution
Stoichiometry
The study of the relationship between the relative quantities of substances taking part in a reaction or forming a compound, typically a ratio of whole integers
Hydrate
A compound, typically a crystalline one, in which water molecules are chemically bound to another compound or element
Water of crystallisation
Water molecules forming an essential part of the crystal structure of some compounds
Percentage composition
The percentage by mass of each element in the compound
Decomposition reaction
A type of chemical reaction in which a single compound breaks down into two or more elements or new compounds
Synthesis reaction
A type of chemical reaction in which two or more simple substances combine to form a complete product
Exothermic reaction
Reactions which transform chemical potential energy into thermal energy
Endothermic
Reactions which transform thermal energy into chemical potential energy
Yield
The measure of the extent of the reaction, generally measured by comparing the amount of product against the amount of product that’s possible
