Definitions Flashcards
What are isotopes?
- Atoms of the same element which therefore have the same number of protons and electrons but a different number of neutrons
What is relative isotopic mass?
- The mass of an isotope relative to 1/12th of the mass of an atom of carbon-12
What is relative atomic mass?
- The weighted mean mass of an atom of an element relative to 1/12th of the mass of an atom of carbon-12
What is ionic bonding?
- The electrostatic attraction between positive and negative ions
What is an ionic lattice?
- A repeating pattern of oppositely charged ions
What is a covalent bond?
- The strong electrostatic attraction between a shared pair of electrons and the nuclei of the bonded atoms
What is electronegativity?
- The ability of a bonded atom to attract the bonding electrons in a covalent bond
What is a hydrogen bond?
- A special type of permanent dipole-dipole interaction found between molecules containing:
- an electronegative atom (such as F, O and N) with a lone pair of electrons
- a hydrogen atom bonded to an electronegative atom
What is periodicity?
- Repeating trends in the physical and chemical properties of elements across a period
What is first ionisation energy?
- The energy required for the removal of 1 mol of electrons from 1 mol of gaseous atoms of an element
What is metallic bonding?
- The strong electrostatic attraction between cations and delocalised electrons
What are giant covalent lattices?
- Networks of atoms bonded by strong covalent bonds
What is disproportionation?
- A redox reaction in which the same element is both oxidised and reduced simultaneously
What is the standard enthalpy change of formation, and its symbol?
- The enthalpy change that takes place when one mole of a compound is formed from its elements under standard conditions, with all reactants and products in their standard states
- ΔfH⦵
What is the standard enthalpy change of combustion, and its symbol?
- The enthalpy change that takes place when one mole of a substance is reacted completely with oxygen under standard conditions, with all reactants and products in their standard states
- ΔcH⦵
What is the standard enthalpy change of neutralisation, and its symbol?
- The enthalpy change that accompanies the reaction of an acid by a base to form one mole of H2O (l) under standard conditions, with all reactants and products in their standard states
- ΔneutH⦵
What is average bond enthalpy?
- When 1 mole of bonds of gaseous covalent bonds is broken
What is a buffer solution?
- A system that minimises pH changes on addition of small amounts of an acid or a base
What is lattice enthalpy, and its symbol?
- The enthalpy change when 1 mole of ionic lattice is formed from its gaseous
ions - ∆LEH
What is the definition of the standard enthalpy change of solution and its symbol?
- The enthalpy change that takes place when 1 mole of a solute dissolves in a solvent
- ΔsolH⦵
What is the definition of the standard enthalpy change of hydration and its symbol?
- The enthalpy change that takes place when 1 mole of gaseous ions forms hydrated ions
- ΔhydH⦵
What is entropy? Include its symbol and units.
- A measure of the dispersal of energy in a system, that is greater the more disordered a system is
- S and J K^-1 mol^-1
What is standard electrode potential?
- The e.m.f of a half cell compared to a hydrogen half-cell
What are the transition elements?
- The d-block elements that form at least one ion with a partially filled d-orbital (not scandium and zinc)
What is a ligand?
- A molecule or ion with a lone pair of electrons that it donates to a central metal ion to form a dative covalent/ coordinate bond
