Physical sciences paper 2 definitions Flashcards
Organic molecules
Molecules containing carbon atoms
Molecular formula
Chemical formula that indicates the type of atoms and the correct number of each in a molecule.
Structural formula
Shows which atoms are attached to which within the molecule. atoms are represented by their chemical symbols and lines are used to represent all the bonds that hold the atoms together.
Condensed structural formula
A notation that shows the way atoms are bonded together in a molecule but does not show all the bond lines.
Hydrocarbons
Organic compounds that consist of hydrogen and carbon only.
Homologous series
Organic compounds that can be described by the same general formula or in which one member differs from the next with a CH2 group.
Saturated compounds
Compounds in which there are no multiple bonds between C atoms in their hydrocarbon chains. example alkanes
Unsaturated compounds
Compounds with one or more multiple bonds between C atoms in their hydrocarbon chains. example alkanes
Functional group
Is a bond or an atom or a group of atoms that determines the physical and chemical properties of a group of organic compounds
Structural isomers
Organic molecules with the same molecular formula, but different structural formulae
Chain isomers
Organic molecules with the same molecular formula, but different types of chains
Positional isomers
Organic molecules with the same molecular formula, but different positions of the side chain, substituents or functional groups on the parent chain.
Functional isomers
Organic molecules with the same molecular formula, but different functional groups
Catenation
The ability of carbon to make bonds with itself.
What makes carbon special?
Carbon has 4 valence electrons and has a valency of 4
Meaning that it can form 4 covalent bonds
C-atoms can combine directly with one another, forming long chains
Carbon can form single, double and triple covalent bonds with itself.
Boiling point
The temperature at which the vapour pressure of a substance equals atmospheric pressure.
Melting point
The temperature at which the solid and liquid phases of a substance are at equilibrium.
vapour pressure
The pressure exerted by a vapour at equilibrium with its liquid in a closed system.
heat of reaction (ΔH)
The energy absorbed or released in a chemical
reaction.
Define exothermic reactions
As reactions that release energy.
Define endothermic reactions
As reactions that absorb energy.
Activation Energy
The minimum energy needed for a reaction to take place.
Activated Complex
The unstable transition state from reactants to products.
Reaction rate
The change in concentration of reactants or products per unit time.
catalyst
A substance that increases the rate of a chemical reaction without undergoing a permanent change itself.