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AQA
Inorganic
3.2.1 - Periodicity
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Paul Evangelou
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Cards (19)
What is periodicity? The
repeating pattern
of physical/chemical properties going across the periods
Atomic radius
decreases
from left to right across a period.
What does the block of an element tell you? The
subshell
in which the
highest energy
electron is in
How are elements in the periodic table arranged?
Elements
are
arranged
according to their
proton number
What is a period on the periodic table? The
horizontal rows
What is a group on the periodic table? The
vertical columns.
What does the group number indicate on the periodic table? The number of
outer electrons
of an element.
What are the 4 blocks of the periodic table?
s
block
p
block
d
block
f
block
What elements are in each block of the periodic table?
s-block = groups
1
and
2
p-block = groups
3
to
0
d-block =
transition
metals
f-block =
radioactive
elements
Along a period, atomic radius
decreases.
Going down a group, atomic radius
increases.
Along a
period
,
ionisation energy increases
Ionisation energy
increases
along a period
Because:
atomic radius decreases, hence
nuclear charge
increases.
This means that the outer electrons are held more strongly so more energy is required to
remove
the outer electron and ionise the atom.
Going down a group, ionisation energy
decreases
Ionisation energy decreases going down a group because:
The
nuclear attraction
between the nucleus and outer electrons
reduces
and shielding also
increases.
Both of these factors mean
less
energy is required to remove the outer electron.
What does the melting point of Period 3 elements depend on?
The
structure
of the element
The
bond strength
Melting points
increase
across Period 3 between sodium and aluminium because
Sodium, magnesium and aluminium are all metals with metallic bonding.
Their melting points increase due to
greater
positive
charge
of their ions
Why does the melting point increase dramatically for silicone in Period 3?
Silicon has a very strong
covalent structure.
So
more energy
is required to break the strong covalent bonds - giving it a very high melting point
Why does argon have an even lower melting point than chlorine ?
Argon is a
noble gas
that exists as individual atoms with a full outer shell of electrons.
This makes the atom very
stable
and the
van der waals
forces between them very
weak.