Deck 11 - Halogens Flashcards
What are the physical properties of the halogens?
- have low melting and boiling points- exist as diatomic molecules.
As you move down the group how do they boiling and melting points of the halogens increase?
As you move down the group the number of electrons increases,leading to an increase in van deer Walls’ forces between molecules.- The boiling points of halogens increase down the group.
What is the electron configuration of group 7 elements?
- They have seven electrons in their outer shell, the highest energy electrons are in the p- sub shell and the elements form part of the p-block of the periodic table.- group 7 elements have one electron fewer than the electronic configuration of a noble gas. - an outer p-sub shell containing 5 electrons.
What is the oxidising power of a halogen an measure of?
The oxidising power of a halogen is a measure of the strength with which the halogen atom is able to attract and cacao true an electron to form an halide ion.
What are. The he most reactive non - metals?
The halogens are and are throng oxidising agents.
As we go down the group the halogens:
Become less reactive because:- the atomic radius increases - the electron shielding increases- the ability to gain an electron into the p-sub shell decreases to form a halide ion.
What is a displacement reaction?
A displacement reaction is a reaction in which a more reactive element displaces a less- reactive element from an aqueous solution of the latter’s ions.
What is disproportionation?
Is the oxidation and reduction of the he same element in a redox reaction.
What happens in a redox reaction of the halogens?
Redox reactions can show that the halogens become less able to form halide ions down the group. Each halogen is mixed with aqueous solutions of different halides. A more- reactive halogen will oxidise and displace a halide of a less reactive halogen. This is often called a displacement reaction. Halogens form solutions of different colours, so any change in colour will show wether a redox reaction has taken place. The mixture is usually shaken up with an organic solvent, such a cyclohexane , to help distinguish between bromine and iodine.
What is the colour of chlorine in water and cyclohexane and as an ion?
In water chlorine is pale- green , in cyclohexane chlorine is pale-green. As an ion chlorine is colourless.
What is the colour of bromine, in water, cyclohexane and as an ion?
It is orange in both water and cyclohexane, and is a colourless ion.
What is the colour of iodine in water,cyclohexane and as an ion?
In water iodine is brown and in cyclohexane iodine is violet. As an ion iodine is colourless.
Why are small amounts of chlorine added to water?
Small amounts of chlorine are added to drinking water to kill bacteria and make water safer to drink.
What is the reaction of chlorine reacting with water and what are the two products formed.
The reaction is a disproportionation reaction. HClO and HCl is produced, both acids. In this reaction chlorine is both reduced and oxidised.
How is house hold bleach made?
Chlorine is only slightly soluble in water and has mild bleaching action. House hold bleach is formed when dilute aqueous sodium hydroxide and chlorine react together at room temperature.- This is also a disproportionation reaction in which chlorine has been reduced and oxidised.- The products are: NaCl, NaClO, H2O
