Ionic Bonding - metal atoms lose electrons
and become positively charged. Non-metal
atoms gain electrons and become negative.
Covalent bond is
between non-metals,
which share electrons.
They are very strong,
with low melting and
boiling points.
Macromolecules
have giant covalent
structures. Arranged
in giant lattices, they
have very high
melting and boiling
points.
Thermosoftening polymers
soften and can be shaped
when hot, but harden when
cooled, because they have no
cross links to hold the shape
together.
Thermosetting
polymers cannot be
reshaped or
softened once
moulded, because
they have cross
links.
Metals are good
conductors of electricity
because of their free
electron.
Ionic compounds
don't conduct
electricity when in
solid form because
their lattice form
means ions cannot
move around.
Graphite
conducts well
because of its
delocalised
electrons.
Atoms
The mass number is total
number of protons and
neutrons
Atomic number is
number of protons
Compounds are
chemically bonded
Isotopes are different atomic
forms of the same element,
which have the same number
of protons but a different
number of neutrons
Carbon-12 and
Carbon-14 are a pair of
isotopes
Ions are atoms that
have lost or gained at
least one electron
In ionic bonding metals
lose electrons to form
positive ions, non-metals
gain electrons to form
negative ions
Relative Mass and
Percentage Yield
Relative Atomic Mass is the same as
the mass number of an element, they
are added together when there is more
than one atom
Number of moles = mass
in g/ relative formula mass
Percentage mass of
an element in a
compound = relative
atomic mass of that
element/relative
formula mass of the
whole compound X100
Empirical formula is an element in its
simplest form, so list all the elements in
a compound and write their
experimental masses. Divide each
mass by the relative atomic mass for
that element. Turn the answers into a
ratio, then simplify the ratio as much as
possible
Calculating masses in reactions
- write out the balanced equation,
work out the relative formula
mass for the parts you need,
divide to get one part then multiply
to get all
Percentage yield compares the
actual outcome with the predicted
outcome. Percentage yield = actual
yield/predicted yield X100