645858
Atoms and reactions
- Isotopes
- Isotopes of the
same element
have:
- Same no. of
protons and
neutrons
- Different
no. of
neutrons in
nucleus
- Different masses
- Same no. of
protons and
neutrons
- Different isotopes
of the same
element react in the
same way because:
- Chemical
reactions involve
electrons
- Neutrons make
no difference to
chemical
reactivity
- Chemical
reactions involve
electrons
- Isotopes of the
same element
have:
- ATOMIC (PROTON) NUMBER - the number of
protons in the nucleus of an atom
- ISOTOPES - atoms of the
same element with different
numbers of neutrons
- MASS (NUCLEON) NUMBER - the
number of particles in the nucleus
- ION - a +ve or -ve charged
atom or (covalently bonded)
group of atoms (molecular ion)
- Atomic masses
- Relative
Isotopic
Mass
- Same as a
mass
number for
an isotope
- Same as a
mass
number for
an isotope
- Relative
Atomic
Mass
- 'Weighted mean
mass' to account
for the
contribution of
each isotope to
overall mass of
an element
- Contribution
made by
isotope
depends
on:
- % abundance of isotope
- Relative
mass of
isotope
- % abundance of isotope
- 'Weighted mean
mass' to account
for the
contribution of
each isotope to
overall mass of
an element
- Relative
molecular
mass
- Mass of a molecule
measured as the
realtive molecular
mass by comparison
with carbon-12
- Add together relative
atomic masses of each
atom in the molecule
- Mass of a molecule
measured as the
realtive molecular
mass by comparison
with carbon-12
- Relative
formula
mass
- Compounds with giant
structures don't exist as
simple molecules
- Add together relative
atomic masses of
each atom making up
formula unit
- Compounds with giant
structures don't exist as
simple molecules
- Relative
Isotopic
Mass
- RELATIVE ISOTOPIC MASS - the mass of an atom of an
isotope compared with one-twelfth of the mass of an atom of
carbon-12
- RELATIVE ATOMIC MASS - the weighted mean mass of an atom of an
element compared with one-twelfth on the mass of an atom of carbon-12
- RELATIVE MOLECULAR MASS - the weighted mean
mass of a molecule compared with one-twelfth of the
mass of an atom of carbon-12
- RELATIVE FORMULA MASS - the weighted mean
mass of a formula unit compared with one-twelfth of the
mass of an atom of carbon-12
- Amount of substance
and the mole
- Amount of substance
- Symbol, n
- Measured
using unit
called the
'mole'
- Based on
standard count
of atoms
- Avagadro's constant
- No. of atoms per mole of
the carbon-12 isotope
- No. of atoms per mole of
the carbon-12 isotope
- Avagadro's constant
- Symbol, n
- Mass of 1 mole of atoms of
any element = the relative
atomic mass in grams
- A 'mole' is the amount of any
substance containing as
many particles as there are
carbon atoms in exactly 12g
of the carbon-12 isotope
- Molar mass - add
together all
relative atomic
masses for each
atom that makes
up a formula unit
- n = m/M
- Amount of substance
- Types of formula
- Empirical formula
- Always used for compunds
with giant structures
- Always used for compunds
with giant structures
- Molecular formula
- Used for compounds that
exist as simple molecules
- Tells you no. of each
type of atom that
makes up a molecule
- Tells you no. of each
type of atom that
makes up a molecule
- Used for compounds that
exist as simple molecules
- Empirical formula
- AMOUNT OF SUBSTANCE - the quantity whose unit
is the mole. Chemists use it as a means of counting
atoms
- AVAGADRO CONSTANT - the no of
atoms per mole of the carbon-12 isotope
- MOLE - the amount of any substance containing as many
particles as there are carbon atoms in exactly 12g of the
carbon-12 isotope
- MOLAR MASS - the mass per mole of a
substance. Units = g mol-1
- EMPIRICAL
FORMULA - the
simplest
whole-number
ratio of atoms of
each element
present in a
compound
- MOLECULE - small
group of atoms held
together by covalent
bonds
- MOLECULAR
FORMULA - the
actual no of
atoms of each
element in a
molecule
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