periodicity 3.2.1 Flashcards
What is the trend in atomic radius across period 3 ?
the radius decreases
why does the atomic radius decrease across period 3 ?
-the proton number increases
-no change in shielding
= increased attraction e- to nucleus
what is the trend of first IE across period three
an increase
why is there there a trend in IE across period three
-There is an increase in nuclear charge
-but no change in shielding
= more energy to remove outer e-
What two elements deviate from the period 3 trend in IE
Al and S
Why does Al deviate from the IE trend
-The outer e- is in the 3p subshell and is shielded by the 3s subshell
= less energy needed to remove outer e-
Why does S deviate from the IE trend
There are four e- in the 3p subshell =two e- share an orbital and repel each other = less energy needed to remove outer e-
what type of bonding is present in these elements - Na Mg Al
metallic
Why does the m.p. change over Na, Mg, Al
-the charges increase
-the size of the ion decreases
=more energy needed to overcome attraction between ions and delocalised e-
what type of bonding and structure is present in silicone
covalent bonding
macromolecular
why is the m.p and b.p of silicone high
lots of strong covalent bonds (four per atom)
what type of bonding and structure are in P4 S8 and Cl2
covalent bonding and simple molecular structure
why do P4 S8 and Cl2 have a low b.p and m.p
they only have IDD between molecules
why is the order of melting points (lowest to highest) is Cl, P, S.
The larger the molecule or the more electrons the molecule contains, the greater the Van der Waals forces and the more energy is needed to overcome the force of attraction.
