Module 2.1 Atoms and reactions Flashcards
Electron relative mass and relative charge:
mass: 1/2000 (basically 0) charge: -1
Proton relative mass and relative charge
mass: 1 charge: +1
neutron relative mass and relative charge:
mass: 1 charge: 0
Mass number tells you?
the total no. of protons and neutrons
Atomic number tells you
no of protons in the nucleus it identifies element as all atoms of the same element have same number of protons.
define Isotope
are atoms with the same number of protons but different number of neutrons.
rutherford nuclear model of atom
tiny positively charged nucleus. mass concentrated there
the nucleus is surrounded by a cloud of -ve electrons
most of the atom is empty space
Bohr improved nuclear model 4 principles
- electrons can only exist in fixed orbitals / shells
- each shell has a fixed energy
- when electron moves between shells electromagnetic radiation is emitted or absorbed
- because the energy of shells is fixed, the radiation will have a fixed frequency.
relative atomic mass Ar
the weighted mean mass of an atom of an element compared to 1/12th of the mass of an atom of carbon 12.
relative isotopic mass
the mass of an atom of an isotope, compared with 1/12th of the mass of an atom of carbon 12.
relative molecular / formula mass Mr
the average mass of a molecule or formula unit compared to 1/12th of the mass of an atom of carbon 12.
Ar can be worked out from isotopic abundances by
- multiple each relative isotopic mass by its % relative isotopic abundances and add up results
- divide by 100
avogrado constant Na
6.02 x 10(23)
number of moles:
no. of particles / avogrado constant
Molar mass is
the mass of one mole of something
the same as Mr
units: g mol-1
room temperature and pressure r.t.p
298k (25c) 101.3 KPa
molar gas volume at r.t.p
24 dm3 mol-1
ideal gas equation
pV= nRT p = pressure (Pa) V= volume (m3) n = no. of moles R = 8.314 J K-1 mol-1 T = temperature (K)
empirical formula
smallest whole no. ratio of atoms of each element in a compound
molecular formula
actual no. of atoms of each type of element in a compound
formula of nitrate ion
NO(3)-
formula of carbonate ion
CO(3) 2-
formula of sulfate ion
SO(4) 2-
formula of hydroxide ion
OH-
formula of ammonium ion
NH(4) +