defintions Flashcards
I what is an ionic bond
electrostatic attraction between oppositely charged ion
what is a homologous series
a family of organic compounds that have the same general formula and similiar chemical properties
what is disproportionation
when an element is oxidised and reduced in the same chemical reaction
what is a dative covalent bond
a covalent bond formed when one atom provides both of the shared electrons
What is the relative atomic mass of an element
the average mass of an atom compared to 1/12 of the mass of an atom of carbon-12
What is the relative formula mass of an element
average mass of a molecule or formula unit compared to 1/12 of the mass of an atom of carbon-12
what is the relative isotopic mass of an element
the mass of an atom of an isotope of an element compared to the mass of 1/12 of the mass of an atom of carbon-12
what is the relative molecular mass of an element
average mass of a molecule compared to 1/12 of the mass of an atom of carbon-12
What does the mass number tell you
total number of protons and neutrons
What is the molecular formula
Actual number of atoms of each element present in a molecule
what is a standard solution
a solution that has a precisely known concentration
What is an alkali
soluble base that releases OH- ions in aqueous solution
what is a ionic crystal
giant lattice of ions that forms because ions are electrostatically attracted in all directions to ions of opposite charge
what is a dipole
a difference in charge between the two atoms caused by a shift in electron density in the bond
what causes permanent dipole -dipole interactions
the positive and negative dipole causes a weak electrostatic force of attraction between molecules
how do hydrogen bonds form
hydrogen is covalently bonded to nitrogen , hydrogen or oxygen
hydrogen has a high charge density as its a small molecule and the elements it can bond to are very electronegative
why is ice more dense than water
hydrogen bonds make the molecules longer so more further apart
what is the behaviour of simple covalent compounds
insoluble in water because most molecules are non polar
low melting and boiling points because of weaker intermolecular forces
dont conduct electricity because most molecules are uncharged
what is the enthalpy of combustion
enthalpy change that takes place when one mole of a substance reacts completely with oxygen under standard conditons
what is the enthalpy change of reaction
enthalpy change that accompanies a reaction in the molar quantities expressed in a chemical reaction
what is the enthalpy change of formation
the enthalpy change that takes place when 1 mole of a compound of formed from its constituent elements
what is hess law
if a reaction can take place by more than one route and the initial and final products are the same then the total enthalpy is the same
what is an orbital
region in a subshell that can hold 2 electrons with opposite spins
