Atoms and Reactions Flashcards
what is empirical formula
simplest whole number ratio of atoms of each element in a compound
what is molecular formula
number and type of atoms of each element in a molecule
what is structural formula
shows how atoms in a molecule are bonded together
what is displayed formula
molecule drawn out by showing all bonds
what does hydrated mean
contains water molecules (water of crystallisation) as part of the crystalline structure
what does anhydrous mean
contains no water of crystallisation
what is water of crystallisation
the water molecules contained within a crystalline structure
1 mol of particles…
contains the same number of particles as there are atoms in exactly 12g of carbon-12
the avogadro constant
the number of particles in 1 mol of a substance - 6.02x10^23
what is a mol
the amount of substance that contains the same number or particles as there are exactly in 12g of carbon 12
what is molar mass
the mass of one mol of a substance. gmol-1
what is molar gas volume
1 mol of any gas occupies the same volume at given temp and pressure - 24dm3 rtp, 22.4dm3 stp
what is atomic number
number of protons in an atom (also number of electrons)
what is mass number
number of protons + neutrons
what is an isotope
atom of the same element with the same number of protons but different number of neutrons and so different masses
what is relative isotopic mass
mass of an isotope compared with 1/12 of the mass of an atom of carbon-12
what is relative atomic mass Ar
weighted mean mass of an atom of an element compared with 1/12 of the mass of carbon-12
what is relative molecular mass mr
mass of a molecule compared with 1/12 of the mass of atom carbon-12
what is relative formula mass
mass of a formula unit compared with 1/12 of the mass of atom carbon-12
what is a mass spectrometer used for
to find the percentage of abundance of the isotopes present in a sample of an element
what is vaporisation
the sample to be tested is turned to a gas
reasons for not 100% yield
- material lost during the reaction (when filtering distilling transferring)
- reaction not going to completion
- completing side reaction occurring alongside main reaction
why do scientists convert as much of the raw materials into useful products
- to increase profits
- to preserve natural resources
- to reduce waste and pollution
what happens with increased pressure
lower volume as same number of particles pushed closer together
what does increased temperature do
higher volume (same number of particles have more energy so moving faster - to keep pressure the same, volume must be greater so same number of collisions with walls of container)
what is an acid
a proton donor and release H+ ions into solution
what is a base
a proton acceptor
what is an alkali
a soluble base
what is a salt
a substance formed when H+ ions in an acid are replaced by metal ions or ammonium ions
what do acids do
release H+ ions into aqueous solution
what does a weak acid do
it only partially dissociates in solution
what does a strong acid do
fully dissociates in solution
what do bases do
neutralises an acid by reacting with H+ ions
what do alkalis do
produce OH- ions in solution
when do salt reactions happen
during a neutralisation reaction
what is oxidation
loss of e- and an increase in ox number
what is reduction
gain of electron and decrease in ox number
what is an oxidising agent
an element compound that causes oxidation of another (accepts e- so are reduced)
what is a reducing agent
an element or compound that causes reduction of another (lose e- so are oxidised)
what are covalent bonds
the electrostatic attraction between the positive nuclei and a shared pair of electrons
what is electronegativity
the ability of atom to attract a bonding pair of electrons in a bind (covalent) to itself
what causes greater electronegativity
the higher the nuclear charge and closer the bonding electrons are to the nucleus
