the halogens Flashcards
.what are the halogens?
The halogens are elements that reside in group 7 of the periodic table, they have 7 electrons in their outer shell.
What is unique about their orbitals?
They lie in the p-block, they have 5 outer shell electrons that are held in a p-orbital
What are some examples of the electronic configuration? In chronological order ie. in order of shells from first to last
Fluorine: 9 electrons
2 e- : 1s orbital
2e- :2s orbital
5e: 2p orbital
Bromine: 35 electrons
1s^2, 2s^2, 2p^6, 3s^2, 3p^6, 4s^2, 3d^10, 4p^5
What are the general properties of the halogens?
- are diatomic molecules
- they have different appearances (darker in colour as we go down the group)
- low m.p. And b.p. As only weak intermolecular forces of attraction exist between the molecules.
What are the trends of the halogens?
Atomic size increases down the group, electronegativity decreases down the group, boiling point and melting point increases
Why does electronegativity decrease down the group ?
The outer shell electrons are held further from the nucleus and there is an increased level of shielding
why does the mp and bp increase down the group ?
Each successive element has an extra shell of electrons which allows for a greater surface area of the molecule so there is a greater degree of London forces of attraction occurring , the lower the bp, the more volatile the element . Down the group we see a physical change in state
Down group 7 (or 17 ) we observe an increase in the melting point of our elements. Why is this ?
There is a greater molecular surface area
Chlorine is a group 7 (or 17) element. The halogens have London forces of attraction between their molecules, describe and explain how these forces of attraction occur.
As there is an uneven distribution of charge, a temporary dipole occurs, this induces a temporary dipole in a neighboring molecule.
