Periodicty Flashcards
Explain the trend of m.p/b.p across period 3 (5)
Na -> Mg -> Al - Metallic Bonding is very strong, this gets stronger the more electrons there are in the outer shell, as they are more delocalised electrons. This means there is greater attraction between the electrons and the nucleus, hence more energy is needed to break teh bonds.
Si (highest) -Macromolecular - many strong covalent bonds, high energy needed to break covalent bonds
(drops)
P4, S8, Cl2- simple molecular : weak van der waals between molecules, so little energy is needed to break them – low mp+ bp
What is the trend of atomic radius across a period?
Atomic radii decrease from left to right across a period.
This is due to:
1. Increasing Nuclear Charge
2. Similar Shielding
The increased number of protons create more positive charge attraction for electrons which are in the same shell for each of the elements in the period.
What is periodicity?
The repeating pattern of physical/chemical properties going across the periods
