Periodicity Flashcards
Wnat is periodicity
the repeating pattern of physical or chemical properties going across periods.
where is the S block on the period table
Group 1 and2
where is the D block on the period table
the retangle with the trasition metals going all the way down, the middle block
where is the P block on the period table
the block on the far rightwith the non-metals
where is the F block on the period table
the elements in the box under the periodic table.
what determines what block an element should be placed in
It’s atomic number
state the trend in Atomic Radius along period 3
The atomic radius decreases as you go across period 3.
explain the trend in atomic radius acroos period 3
as you go along the period, the number of protons increases - this increase in positive charge means there is a greater positive attraction for the electrons which are in the same shell with similar sheilding.
why does the extra electron in period 3 elements not affect the atomic radius trend
they don’t affect the trend as they are added the outer energy level which doesnt provide any extra sheilding
State and explain the general trend in Ionisation energy across period 3
the general ionisation energy trend increases across the period. this is because the increase in number of protons increases the nuclear attraction towards the outer electrons - increase in nuclear charge without extra sheilding
Explain the drops in IE between group 2 (eg - Mg) and 3 (eg - Al)
the outer in electron in Al is in a 3P orbital which has a slightly higher enegery than the 3S (orbital of last e- in Mg) orbital, so that electron is found further away from the nucleus. the distacne and the extra sheilding from the 3s2 electrons, both override the effect of increased nuclear charge resulting in the IE slightly droping.
Explain the drops in IE between group 5 (eg - P) and 6 (eg - S)
in P and S the sheilding is identical and the electron is being removed from an idfentical orbital with 2 electrons. But in P the electron is being removed from a singly ocupied orbital, in S the electron is being removed from a doubly occupied orbital. the elctron repulsion in S makes it easier to remove it from the shared orbital - hence why the drop.
Why does the melting point vary across the period
varies cos it depends on the structure and bonding of elements within them.
Explain the MP for Na, Mg, Al
they are all metals. the metallic bonds get stronger along, cos of the increase in positive charge and the increase in delocalised electrons and the decreasing radius all increase the MP along these elements.
Explain why silicon has the MP it has
Silicon is macromolecular, with a tetrahedral structure and strong covalent bonds that need a lot of energy to overcome, so Si has a massive MP (the biggest in the period)
