Y12 Definitions Flashcards
Relative isotopic mass
The mass of an isotope relative to 1/12 of the mass of carbon 12
Relative atomic mass
The weighted mean mass of an element relative to 1/12 of the mass of carbon 12
Ammonium
NH4+
Hydroxide
Oh-
Nitrate
NO3-
Nitrite
NO2-
Hydrogen carbonate
HCO3-
Manganite VII
MnO4-
Carbonate
CO32-
Sulphate
SO42-
Sulfite
SO32-
Dichromate VI
Cr2O72-
Phosphate
PO43-
Polyatomic molecules
N2 P4 S8
Mole
The amount of substance that contains 6.02 x10^23 particles
Molar mass
Mass per mole of a substance units are gmol^-1
Molecular formula
The actual number of atoms of each element in a molecule
Empirical formula
The simplest whole number ratio of atoms of each element in a compound
Relative molecular mass
Compares the mass of the molecule with the mass of an atom of carbon 12 calculated by adding atomic masses together
Relative formula mass
Compares the mass of the formula unit with the mass of an atom of carbon 12 calculated by adding together the relative atomic masses of the elements in the empirical formula
Molecular formula
Molecular mass divided by empirical formula mass
Room temperature and pressure
20°C 101KPA or one atmosphere
Ideal gas equation
PV= nRT P= pressure Pa V= volume m^3= 1000dm^3 n= moles R= gas constant= 8.31j/mol/k T=temp= K
Assumptions real gas equation
Random motion elastic collisions negligible size no intermolecular forces
Stoichiometry
The ratio balancing an equation
Atom economy
A measure of how well the atoms have been utilised
Reactions with high at McConomy is produced a large proportion of desired product few unwonted waste products they are important the sustainability and make the best use of natural resources based on balanced chemical equations assume 100% yield atom economy equals some of mola masses of desired Products divided by some of mola masses of all products times 100
Bases
Metal oxides metal hydroxide metal carbonate and ammonia NH3
Alkalis
A base the dissolves in water releasing hydroxide ions into the solution
Acid plus base
Salt and water
Dissociation of sulphuric acid
Only one of the two hydrogen atoms is a strong acid’s are only partially dissociates to form HSO4-
This then disassociates to form SO42-
Titrations
Technique used to accurately measure the volume of one solution that reacts with another solution
Ox number F
-1
Special cases oxidation number is
H in metal hydrides(NaH)= -1
O in peroxide = -1
O bonded to F= +2
Max no of electrons in a shell
2n^2
Atomic orbitals
A region around the nucleus that can hold up to 2 electrons with opposite spins
Patterns of 4S and 3-D subs shells
4S fills before 3-D and empties before as once fills 3-D energy levels fall below 4S energy levels
Covalent bond
Strong electrostatic attraction between shared pair of electrons and the nuclei of the bonded atoms
Boron bond forming
Boring has three electrons in outershell when all three are bonded in covalent bonding only six electrons are in its outer shell
Expanding the octad
Occurs after the third shell depends how many unpaired electrons
Dative covalent bonds
Form when there is originally a lone pair of electrons on one of the bonded atoms for example ammonium is formed when an ammonia and hydrogen ions react
2 electron regions
Linear bond angle 180° example CO2
Three electron regions
Trogonal planar Bond angle 120° example BF3
4 electronic regions
Tetrahedral bond angle 109.5°CH4
Six electron regions
Octahedral 90° SF6
Electronegativity
The attraction of a bonded atoms for the pair of electrons in a covalent bond
Intermolecular forces
Week interactions between dipoles of different molecules
London forces
Induced dipole dipole interactions
Simple molecular substance
Made up of simple molecules small units containing definite number of atoms with a definite molecular formula such as H2O CO2 H2
Hydrogen bonds can form with
Oxygen nitrogen fluorine
Percentage error
Error/amount x100
Dipole
A difference in charge between two atoms caused by shift in electron density in the bond
Entropy units
J/K/mol
Standard entropy
The entropy of one mole of a substance understand his condition always positive
Catalyst for breakdown of hydrogen peroxide
Magnesium oxide MNO2
entropy
A term used for the dispersal of energy within the chemicals making up the chemical system
Free energy change Delta G
The overall change in energy during a chemical reaction
Enthalpy
The measure of the heat energy in a chemical system
Ethanolic acid
CH3COOH