Year 1 Definitions Flashcards
What are isotopes?
Atoms of the same element (same number of protons and electrons) with different numbers of neutrons and different masses.
What is relative isotopic mass?
The mass of an atom of an isotope compared with 1/12 of the mass of an atom of Carbon-12.
What is relative atomic mass?
The weighted mean mass of an atom of an element compared with 1/12 of the mass of an atom of Carbon-12.
What is an atomic orbital?
A region around the nucleus that can hold up to two electrons, with opposite spins.
What does anhydrous mean?
When all the waters of crystallisation have been removed from a compound.
What does hydrated mean?
When water of crystallisation is present in a crystal compound.
What is water of crystallisation?
The water present in a compound giving the compound a crystalline appearance.
What is the equation for percentage yield?
Percentage (%) Yield = Actual mass of product / Theoretical mass of product x 100
What is the equation for atom economy?
Atom Economy = Molecular mass of desired product / Molecular mass of ALL products x 100
What is an acid?
Proton (H+) donor.
What is a base?
Proton (H+) acceptor.
What is an alkali?
A soluble base that dissolves in water to release OH- ions in aqueous solution.
What is oxidation?
The loss of electrons / increase in oxidation number (state).
What is reduction?
The gain of electrons / decrease in oxidation number (state).
What is an oxidising agent?
A reagent which oxidises another species (and is reduced itself) by gaining electrons.
What is a reducing agent?
A reagent which reduces another species (and is oxidised itself) by losing electrons.
What is a redox reaction?
A reaction where both oxidation and reduction takes place.
What is disproportionation?
A reaction in which the same element is both oxidised and reduced.
What is a metallic bond?
Strong electrostatic attraction between positively charged ions (cations) and delocalised electrons.
What is an ionic bond?
Strong electrostatic attraction between positive and negatively (oppositely) charged ions.
What is a covalent bond?
Electrostatic attraction between a shared pair of electrons and the nuclei of the bonded atoms.
What is a dative (co-ordinate) covalent bond?
The strong electrostatic attraction between a shared pair of electrons and the nuclei of the bonded atoms, where only one of the atoms supplies both the electrons shared.
What is electronegativity?
The ability of an atom to attract the bonding electrons towards itself in a covalent bond.
What is periodicity?
The repeating trends in physical and chemical properties.
Elements are arranged by increasing atomic (proton) number and in groups with similar chemical properties.
Why is Mg classed as a s block elements?
An s-block element has its highest energy electron in a s subshell.
This answer can be applied to elements in other blocks too!
What is first ionisation energy?
The energy required to remove one electron from each atom in one mole of gaseous atoms to form one mole of gaseous 1+ ions.
What is metallic bonding?
Strong electrostatic attraction between positively charged ions (cations) and delocalised electrons.
What is an exothermic reaction?
A reaction where heat energy is released to the surroundings (ΔH is negative).
What is an endothermic reaction?
A reaction where heat energy is absorbed from the surroundings (ΔH is positive).
What is average bond enthalpy, ΔEHϑ?
The average enthalpy change for the breaking of 1 mole of bonds in gaseous molecules.
What are standard conditions?
Temperature = 25°C (298K), Pressure = 1 atm (100 kPa), and all solutions must have a concentration = 1.00 mol dm-3.
What is the standard enthalpy change of neutralisation, ΔneutHϑ?
The enthalpy change that accompanies the formation of one mole of H2O(l) from neutralisation, under standard conditions.
What is the standard enthalpy change of formation, ΔfHϑ?
The enthalpy change when one mole of a compound is formed from its elements in their standard states under standard conditions.
What is the standard enthalpy change of combustion, ΔcHϑ?
The enthalpy change for complete combustion of one mole of a substance under standard conditions, all reactants and products being in their standard states.
What is the rate of reaction?
The change in concentration of a reactant or a product per unit time.
Rate = Concentration of reactant (or product) mol dm-3; UNITS = mol dm-3 s-1
What is activation energy?
The minimum energy required to start a reaction by breaking bonds.
What is heterogeneous catalysis?
Catalysis of a reaction in which the catalyst has a different physical state from the reactants.
What is homogeneous catalysis?
Catalysis of a reaction in which the catalyst and the reactants are in the same physical state.
What is dynamic equilibrium?
- Exists in a closed system
- when the rate of the forward reaction is equal to the rate of the reverse reaction
- and the concentrations of reactants and products do not change.
What is Le Chatelier’s principle?
When a system in dynamic equilibrium is subjected to change, the equilibrium position will shift to minimise the change.
What is a homologous series?
A series of organic compounds having the same functional group but with each successive member differing by CH2.
What is a functional group?
An atom/group responsible for the characteristic reactions of a compound.
What are** structural isomers?**
Compounds with the same molecular formula but different structural formulae.
What is** homolytic fission?**
The breaking of a covalent bond where one electron from the bonding pair goes to each atom to form 2 radicals.
What is heterolytic fission?
The breaking of a covalent bond where both electrons from the bonding pair go to the same atom to form 2 ions.
What is a radical?
A species with an unpaired electron.
What is a curly arrow?
Movement of an electron pair.
What are stereoisomers?
Compounds with the same structural formula but with a different arrangement in space.
What is an electrophile?
An electron pair acceptor.
What is a nucleophile?
An electron pair donor.
