Group 7 Flashcards
What block are they in?
P block
What bond is in the halogen molecule?
Covalent
Diatomic?
Yes
What structure do they have?
Simple molecular
What happens to the colour as you go down the group?
Increases down the group
What happens to volatility down the group?
Decreases down the group
Are there temporary or permanent dipoles?
Temporary
What happens when there is more electrons in the molecule?
The greater the induced dipoles and the greater the attraction between the molecules
Fluorine and chlorine state at room temp and pressure?
Gas
Bromine state at room temperature and pressure?
Liquid
Iodine and astatine state at room temperature and pressure?
Solid
What happens to electronegativity as you go down group 7?
Electronegativity decreases- elements become less electronegative.
Atomic radius increases as well as the number of protons
The outermost electron is further away from the nucleus- decreasing the nuclear attraction
More protons as well- increases the nuclear charge
Harder for the atom to attract the shared pair of electrons in a covalent bond
Shielding increases
What electron structures do group 7 end in?
P5
Are group 7 elements reduced or oxidised?
Reduced d
Are group 7 elements reducing agents or oxidising agents?
Oxidising agents
Br2 and Cl2?
Aqueous layer- stays orange
Organic layer- stays orange
Which layer is always at the top?
The organic layer
The aqueous layer is always at the bottom
What reaction is between bromine and chlorine?
No reaction
I2 and Cl-?
Organic- brown
Aqueous- violet
Reaction between I2 and Cl2?
No reaction
Cl2 and Br-?
Aqueous layer goes from colourless to orange
Organic layer goes from colourless to orange
I2 and Br-?
Organic layer- stays brown
Aqueous layer- stays violet
Cl2 and I-?
Aqueous layer- goes from colourless to brown
Organic layer- goes from colourless to violet
Reaction between Cl2 and I-?
2I + Cl2 -> I2 + 2Cl-
Br2 and I-?
Aqueous layer goes from orange to brown
Organic layer goes from orange to violet
Reaction between bromine and I-?
Br2 + 2I- -> I2 + 2Br
Trend in reactivity down group 7?
They get less reactive
What is the strongest oxidising agent?
Chlorine (strongest)
Bromine (middle)
Iodine (weakest
Why does electron affinity decrease down the group?
Atomic radius increases
Shielding increases
Nuclear attraction decreases so it becomes harder to gain an electron
What type of reaction is chlorine and water?
Disproportionation as Cl2 is being oxidised and reduced
What are the products formed for chlorine and water?
Hydrochloric acid and chloric acid
What happens to indicator paper when chlorine water is added?
Indicator paper turns red due to the hydrochloric acid
The colour is removed from the indicator paper due to the ClO-
What are the advantages of sterilising water?
Prevents waterborne diseases (cholera)
Why do some people think we should not use residual disinfectant systems?
Chlorine is toxic in excess and can react with hydrocarbons from organic substances in pipes/water to form chlorinated hydrocarbons such as chloroform- some of which are carcinogens
CL- with silver nitrate?
White ppt
Br- with silver nitrate?
Cream ppt
I- with silver nitrate?
Yellow ppt
Cl- with dilute ammonia?
Ppt disappears
Br- with dilute ammonia?
No change
I- with dilute ammonia?
No change
Cl- with concentrated ammonia?
Ppt disappears
Br- with concentrated ammonia?
Ppt disappears
I- with concentrated ammonia?
No change
What increases as you go down the group?
Reducing ability
Atomic radius
Boiling points
What decreases as you go down the group?
Electronegativity
Oxidising ability
What happens to the oxidising power of the halogens as you go down the group?
Oxidising power decreases
What happens to the reducing power of the halide ions as you go down the group?
Increases
