10.1 Halogens Flashcards
How does the appearance of halogens change down the group
. They get darker and denser
Eg fluorine is a pale yellow gas whilst iodine is a black solid
What are the colours of flourine gas, chlorine gas, bromine liquid, and iodine solid
Pale yellow gas
Greenish gas
Brown/red liquid
Black solid
Why are the properties of fluorine atypical
. The F-F bond is unexpectedly weak, compared with the trend for the rest of the halogens
. Small size of fluorine atom leads to repulsion between non bonding electrons because they are so close together
Trend in size of atomic radius going down group 7
Increases as an energy level is added for each period you go down.
This means the outer shell is getting further from nucleus, so atomic radius increases
What is electronegativity
. Measure of the ability of an atom to attract electrons, or electron density, towards itself within a covalent bond
Trend in electronegativity down group 7
. It decreases down the group
. It depends on attraction between nucleus and outer electrons, so in turn depends on the number of protons in the nucleus, and the distance between the nucleus and bonding electrons (plus the shielding from inner shells).
. As you go down group there are more shells, shielding outer electrons and they’re also getting further from nucleus so are less attracted to nucleus.
How do melting and boiling points change going down the group
They increase as you go down the group
. Because larger atoms have more electrons which makes the Van Der Walls forces between the molecules stronger.
The lower the boiling point, the more volatile the element so chlorine is a gas at room temp
What does volatile mean
It’s the ability of a substance to vapourize readily from liquid to gas or solid to gas
What is formed when chlorine Cl2 reacts with cold aqueous NaOH
NaCl and NaClO
