3.2.1 Periodicity Flashcards
Structure of the periodic table
Group = vertical
Period = horizontal
Periodicity definition
Study of repeated trends in a period
pattern in properties of an element across a period
Atomic radius trends on the periodic table
Atomic radius decreases along a period
As nuclear charge increases and shielding remains constant
Atomic radius increases down a group
As shielding increases which reduces the attraction
Ionisation energy trends on the periodic table
Ionisation energy along a period increases
As the ar is is decreasing and the nuclear charge is increasing
So are held strongly together so more energy is needed to separate
Down a group it decreases
As nuclear attraction decreases as shielding increases less energy needed
Melting point is period 3
increases till si
then drops down for p
then increases up to s
then decreases to cl and ar
cl and p lower than na
s higher than na
Reasons for the different melting points in group 3
Na,mg.al = metal sso have metallic bonding. Increase across as greater positively charged ions. More e released - so electrostatic forces increase
Si - giant covalent - string covalent bonding
P,s,cl - simple covalent - weak van der waals
Ar - very stable as is a full outer shell has weak van der waals
periodic table
list of all known elements in order of increasing atomic mass
lanthandides and actinides
lanthadides - top
are metals which are not often enocountered
acetinindes radiactove metals found in trace quantities
make up f block
trend period 3 react to form
group 1,2,3 - giant ionic compounds - loose there outer electrons to form ionic compound
group 4-si
4 electrons in outer shell meaning 4 covalent bonds - giant covalent
group5,6,7
covalent compounds or ionic compounds
group 0 - full outer shell - uncreative
non metals melting point
vander walls - for molecular
vander walls effected by the number of electrons and how closely they pack together
bonding period 3
na,mg - meatalic bonding
si - macromolecular
p,s,cl - simple molecular
ar - nobal gas
metals melting point
effected by the strength of the metallic bonding
- depends on the sea of delocalized electrons
- charge of the ion
- meaning stronger attraction in lattice
how to measure atomic radius
can only be measured by 2 atoms -has no clear point the electron density drops to 0
ionisation elegy anomalies
AL looses from a higher energy level 3p not 3s
s - outer most electron is paired in p orbital meaning easily removed
why sulfur has a higher melting point than phosphorus
becuase s8 bigger than p4 - larger molecule
meaning more vnader vaal
