Module 2 - chapter 2 and 3 key terms Flashcards
Atomic (proton) number Z
Number of protons in the nucleus
Mass (nucleon) number A
Number of particles (protons and neutrons) in the nucleus.
Isotopes
Atoms of the same element with different numbers of neutrons but the same number of protons, hence they have different masses.
Ions
Positively or negatively charged atoms or (covalently bonded) groups of atoms (a molecular ion). Formed by the loss or gain of one or more electrons from an atom or group of atoms
Relative isotopic mass
(RIM) the mass of an atom of an isotope compared with 1/12th of the mass of carbon-12.
Relative atomic mass
Ar, the weighted mean mass of an atom of an element compared with 1/12th of the mass of carbon-12.
Relative molecular mass
Mr - the weighted mean mass of a MOLECULE compared with 1/12th of the mass of an atom of carbon-12 (only applies to simple covalently bonded molecule like O2 or CO2)
Relative formula mass
the weighted mean mass of a formula unit compared to the mass of an atom of carbon-12
RFM can apply to ionic substances as these occur as giant lattices
Empirical formula
Shows the simplest ratio of atoms in a compound.
Concentration
The concentration of a solution is the amount of solute (in mol) dissolved per 1 dm³ (1000cm³) of solution.
Dilute
Process of decreasing the concentration of a solute in solution. We add more solvent without adding more solute, therefore reducing the concentration.
Theoretical yield
The maximum possible amount of product.
Percentage yield
(actual yield / theoretical yield ) x 100
Limiting reagent
The reactant that is not in excess will be completely used up first and stop the reaction, this is the limiting reagent.
Atom economy
The atom economy of a chemical reaction is a measure of how well atoms have been utilised.
Avagadro’s constant
6.02 x 10^23
Molecular Formula
The number of atoms of each element in a molecule
Hydrated Salts
Many coloured crystals are hydrated - water molecules are part of their crystalline structure.
Water of crystallisation
Is the water molecules that are part of the crystalline structure of hydrated salts.
Standard solution
Is a solution of known concentration.
Molar gas volume
Is the volume of per mole of gas molecules at a stated temperature and pressure.
Stoichiometry
In a balanced equation, the balancing numbers give the ratio of the amount, in moles, of each substance.
Binary compound
A compound that contains two elements only.
