the periodic table Flashcards
(44 cards)
what is the periodic table?
its a list of elements arranged in order of increasing proton numbers
what is a group?
its a vertical coloumn of elements
there are 8grps, I-VII n O
it runs frm top to bottom
what is a period?
its a horizontal coloumn of elements
there are 7 periods
runs frm left to right
Periodic trends:
metallic n non-metallic properties across the period
from left to right across a period, thr is a decrease in metallic properties n an increase in non-metallic properties:
from very metallic to metalloids(Silicon) to non-metallic
better RAs to better OAs
from basic to amphoteric to acidic
metallic properties down a grp
thr is an increase in metallic properties
non-metallic properties down a grp
thr is a decrease in non-metallic properties
why is the metallic properties down a grp as such?
going down a grp, the size of the atoms increases so atomic radius increases so the -vely charged valence e of an element will b further away frm the +vely charged nucleus so an element down a grp will thus lose its valence e more easily so its more reactive
electronic structure:
we can obtain the elctronic config frm
the element’s proton no.-> deduce period n grp no.
the no. of eshells is the same as
the period no. of the element
the no. of valence e is the same as
the grp no. of the elements
elements w the same no.of valence e hv
similar chemical n physical properties tht r determined by no. of valence e
group 1 elements: Alkali Metals
all the elements hv similar properties since thy belong in the same grp
the physical properties of alkali metals
they are soft n can b cut thru easily
low mp n bp which decreases down the grp
low densities which increases down the grp
thy r vry shny metals but whn thy r cut since thy r so reactive thyll oxidise n bcome black
chemical properties of alkali metals
- they are highly reactive metals so they have to be stored in oil to prevent it frm reacting w air n water
- thy can just lose 1 valence e to attain noble gas electronic structure
- reactivity increases down the grp bcos down the grp, atomic radius increases so it is easier to lose the valence e since the electrostatic forces of e btwn the +vely charged nucleus n negatively-charged valence e gets weaker so its easier to lose e
reaction tht alkali metals can take part in
- they can react w cold water to form alkali + hydrogen
they r all exothermic!!
are alkali metals powerful oa or ra?
powerful ra!! since all alkali metals form ions w a charge of +1 by losing 1e frm the outer shell which thy can lose easily/readily
reducing power increases down the grp as the metals has a higher tendency to lose e down the grp( n bcome oxidised)
alkali metals form what kind of cmpnds?
form ionic cmpnds n their cmpnds hv similar chemical formulas n r soluble in water
whn placed in a fire, Li glows:
bright red
whn placed in a fire, Na bcomes:
bright yellow
whn placed in a fire, K produces a:
violet colour
whn placed in a fire, rubidium is:
dark red
whn placed in a fire, caesium is:
light blue
Group 7 elements: Halogens;
physical properties of halogens
halogens r non-metals tht exist as diatomic covalent molecules w SMS(weak wander Waals FOA)
it has low mp bp which increases down the grp
it is coloured and the colour bcome darker/colour intensity increases down the grp
density increases down the grp
why does halogens have an increasing mp n bp down the grp?
down the grp the molecular masses/sizes of halogens increase so the vdwfoa btwn molecules increases so a highr amt of heat energy is req to overcome the foa so mp/bp increases
