Chemistry Definitions

Chemistry glossary AS

The coefficient is the technical term for the ___ written in front of ___ when ___ an ___.

The coefficient is the technical term for the number written in front of species when balancing an equation.

A spectator ion is there both ___ and ___ the ___ but is not ___ in the ___.

A spectator ion is there both before and after the reaction but is not involved in the reaction.

In a displacement reaction, one ___ another, less ___, ___ in a ___.

In a displacement reaction, one element replaces another, less reactive, element in a compound.

In a precipitation reaction, an ___ is formed when ___ are ___.

In a precipitation reaction, an insoluble solid is formed when two solutions are mixed.

The molar mass is the ___ per ___ of a ___. It has the symbol ___ and the units ___.

The molar mass is the mass per mole of a substance. It has the symbol M and the units g mol⁻¹.

The Avogadro constant is the ___ of ___ in ___ of a ___. It has the value ___ × ___ and the symbol ___.

The Avogadro constant is the number of particles in one mole of a substance. It has the value 6.02 × 10²³ mol⁻¹ and the symbol L.

A mole is the ___ of ___ that contains the ___ of ___ as the ___ of ___ in exactly ___ of ___.

A mole is the amount of substance that contains the same number of particles as the number of carbon atoms in exactly 12 g of carbon-12.

A hydrate is a ___ containing ___ of ___, represented by formulae such as CuSO₄___5H₂O .

A hydrate is a compound containing water of crystallisation, represented by formulae such as CuSO₄·5H₂O .

The theoretical yield is the ___ of a ___ in a ___, assuming ___ and ___.

The theoretical yield is the maximum possible mass of a product in a reaction, assuming complete reaction and no losses.

The actual yield is the ___ obtained in a ___.

The actual yield is the actual mass obtained in a reaction.

The percentage yield is the ___ the ___, expressed as a ___.

The percentage yield is the actual yield divided by the theoretical yield, expressed as a percentage.

Atom economy is the ___ of the ___ the ___ of the ___ of ___ the ___, expressed as a ___.

Atom economy is the molar mass of the desired product divided by the sum of the molar masses of all the products, expressed as a percentage.

The empirical formula is the ___ of ___ of each ___ in a ___.

The empirical formula is the smallest whole-number ratio of atoms of each element in a compound.

The molecular formula is the ___ of ___ of each ___ in a ___.

The molecular formula is the actual number of atoms of each element in a molecule.

The molar volume is the ___ occupied by ___ of ___. This is normally ___ dm³ or ___ cm³ at ___.

The molar volume is the volume occupied by 1 mole of any gas. This is normally 24 dm³ or 24 000 cm³ at r.t.p.

A solute is a ___ that is ___.

A solute is a substance that is dissolved.

A solvent is a ___ that ___ a ___.

A solvent is a substance that dissolves a solute.

A solution is a ___ in a ___.

A solution is a solute dissolved in a solvent.

The mass concentration (of a ___) is the ___ (in ___) of the ___ the ___ of the ___.

The mass concentration (of a solution) is the mass (in g) of the solute divided by the volume of the solution.

The molar concentration (of a ___) is the ___ (in ___) of the ___ the ___ of the ___.

The molar concentration (of a solution) is the amount (in mol) of the solute divided by the volume of the solution.

Parts per million (ppm) is the ___ of ___ of ___ in ___ of another ___. It is a ___ used to describe ___. Usually, ‘parts’ refers to ___ of ___, or to ___ of ___.

Parts per million (ppm) is the number of parts of one substance in one million parts of another another substance. It is a measure used to describe concentration. Usually, ‘parts’ refers to masses of both substances, or to volumes of both substances.

The atomic number (Z) is the number of ___ in the ___ of an ___.

The atomic number (Z) is the number of protons in the nucleus of an atom.

The mass number is the ___ of the ___ of ___ and the ___ of ___ in the ___ of an ___.

The mass number is the sum of the number of protons and the number of neutrons in the nucleus of an atom.

Isotopes are ___ of the ___ that have the ___ but ___.

Isotopes are atoms of the same element that have the same atomic number but different mass numbers.

The relative atomic mass (Aᵣ) (of an ___) is the ___ of an ___ of the ___ compared to ___ of the ___ of an ___ of ___.

The relative atomic mass (Aᵣ) (of an element) is the weighted mean mass of an atom of the element compared to 1/12 of the mass of an atom of carbon-12.

The relative isotopic mass is the mass of an ___ of a ___ relative to ___ of the ___ of an ___ of ___.

The relative isotopic mass is the mass of an individual atom of a particular isotope relative to 1/12 of the mass of an atom of carbon-12.

The quantum shell is the ___ of an ___.

The quantum shell is the energy level of an electron.

An orbital is a ___ within an ___ that can hold up to ___ with ___.

An orbital is a region within an atom that can hold up to two electrons with opposite spins.

The electronic configuration (of an ___) is the ___ of ___ in each ___ in each ___ of the ___.

The electronic configuration (of an atom) is the number of electrons in each sub-shell in each energy level of the atom.

Hund’s rule states that ___ will ___ the ___ before ___ takes place.

Hund’s rule states that electrons will occupy the orbitals singly before pairing takes place.

The Pauli Exclusion Principle states that ___ cannot ___ the ___ unless they have ___. ___ is usually shown by using ___ and ___.

The Pauli Exclusion Principle states that two electrons cannot occupy the same orbital unless they have opposite spins. Electron spin is usually shown by using upward and downward arrows.

The first ionisation energy (of an ___) is the ___ required to ___ an ___ from each ___ in ___ of ___ in the ___.

The first ionisation energy (of an element) is the energy required to remove an electron from each atom in one mole of atoms in the gaseous state.

The second ionisation energy (of an ___) is the ___ required to ___ an ___ from each ___ in ___ of ___ in the ___.

The second ionisation energy (of an element) is the energy required to remove an electron from each singly charged positive ion in one mole of positive ions in the gaseous state.

The third ionisation energy (of an ___) is the ___ required to ___ an ___ from each ___ in ___ of ___ in the ___.

The third ionisation energy (of an element) is the energy required to remove an electron from each doubly charged positive ion in one mole of positive ions in the gaseous state.

The groups are the ___ in the ___.

The groups are the vertical columns in the Periodic Table.

The periods are the ___ in the ___.

The periods are the horizontal rows in the Periodic Table.

Periodic properties (periodicity) are ___ of ___, ___ and ___, which can be predicted using the ___ and explained using the ___ of the ___.

Periodic properties (periodicity) are regularly repeating patterns of atomic, physical and chemical properties, which can be predicted using the Periodic Table and explained using the electron configurations of the elements.