Group 7 Flashcards
State and explain the trend in group 7 melting/boiling points
Increases because:- Halogens exist as non-polar diatomic molecules- Weak van der waals forces exist between the molecules (IMF’s) which are broken when boiled/melted- Induced dipole forces become stronger down the group as Mr increases this is because more electrons involved in the induced dipoles
State and explain the trend in group 7 electronegativity
Decreases because:- Shielding increases - Effective nuclear charge decreases - Decreases its ability to attract a bonding pair of electronse.g. fluorine can form a stronger dipole than iodine
What state is fluorine in at room temp?
Gas
What state is chlorine in at room temp?
Gas
What state is bromine in at room temp?
Liquid
What state is iodine in at room temp?
Solid
What are halogens?
Oxidising agents
What are halides?
Reducing agents
Which halogen is the strongest oxidising agent and why?
Fluorine because it has the highest effective nuclear charge due to lowest shielding
Which halogen is the weakest oxidising agent and why?
Iodine because it has the lowest effective nuclear charge due to highest shielding
Which halide is the strongest reducing agent and why?
Iodide because it has the lowest effective charge due to having the highest shielding
Which halide is the weakest reducing agent and why?
fluoride because it has the highest effective charge due to having the lowest shielding
What type of reaction occurs between a halogen (aq) and a halide (aq)?
A displacement reaction
What is observed when Cl2 reacts with Br-?
Orange solution
What is observed when Cl2 reacts with I-?
Brown Solution
What is observed when Br2 reacts with I-?
Brown Solution
What is the first step in testing for halide ions?
Add acidified silver nitrate (H+/AgNO3 (aq))
Why do we add acidified silver nitrate when testing for halide ions?
The HNO3 neutralises and carbonate or hydroxide impurities present which interfere with the halide test.
What does Ag2CO3 form?
White precipitate