Module 2: Definitions Flashcards
Define relative formula mass.
The weighted mean mass of the formula unit of a compound compared with one-twelfth of the mass of an atom of carbon-12.
Define relative atomic mass.
(Ar)
The weighted mean mass of an atom of an element compared with one-twelfth of the mass of an atom of carbon-12.
Define relative isotopic mass.
The mass of an atom of an isotope compared with one-twelfth of the mass of an atom of carbon-12.
Define relative molecular mass.
(Mr)
The weighted mean mass of a molecule of a compound compared with one-twelfth of the mass of an atom of carbon-12
What is an ionic bond?
Electrostatic force of attraction between cations and anions.
What is a metallic bond?
Electrostatic attraction between cations (positive metal ions) and delocalised electrons.
What is a covalent bond?
Strong electrostatic attraction between a shared pair of electrons and the nuclei of the bonded atoms.
What are isotopes?
Atoms of the same element with different numbers of neutrons and different masses.
What are IMF’s?
Intermolecular force.
An attractive force between molecules. Intermolecular forces can be London forces, permanent dipole-dipole interactions or hydrogen bonding.
What is a hydrogen bond?
A strong dipole-dipole attraction between an electron-deficient hydrogen atom of -NH, -OH or HF on one molecule and a lone pair of electrons on a highly electronegative atom containing N, O or F on a different molecule.
What is the empirical formula?
The formula that shows the simplest whole-number ratio of atoms of each element present in a compound.
What is the molecular formula?
A formula that shows the number and type of atoms of each element present in a molecule.
Define stoichiometry.
The ratio of the amount, in moles, of each substance in a chemical equation (essentially the ratio of the balancing numbers).
Define anhydrous.
Containing no water molecules.
Define hydrated.
A crystalline compound containing water molecules.
Define water of crystallisation.
Water molecules that are bonded into a crystalline structure of a compound.
Define dative covalent.
A shared pair of electrons in which the bonding pair has been provided by one of the bonding atoms only; also called a coordinate bond.
What is Avogadro’s constant?
(Na)
The number of atoms per mile of the carbon-12 isotope.
6.02x10^23 mol^-1
Define molar mass.
(M)
The mass per mole of a substance, in units of gmol^-1.
What is molar gas volume?
(Vm)
The volume per mole of gas molecules at a stated temperature and pressure.
What is a mole?
The amount of any substance containing as many elementary particles as there are carbon atoms in exactly 12g of the carbon-12 isotope, that is, 6.02x10^23 particles.
What is percentage yield?
% yield =
actual amount of product (mol)
__________________________________
theoretical amount of product (mol)
X100
Define atom economy.
Sum of molar masses of desired products
/ divided by
Sum of molar masses of all products
Å ~ 100
What is sustainability?
Carrying out chemical processes without depleting the Earth’s natural resources or damaging the environment.
