Group 7,the halogens Flashcards
Describe the state in which each of the halogens exist at room temperature
1) fluorine (F2) is a pale yellow gas
2) chlorine (Cl2) is a greenish gas
3) bromine (Br2) is a red-brown liquid
4) iodine (I2) is a black solid
What is the trend in electronegativity as you go down group 7
The electronegativity decreases as you go down group 7
What happens to the size of the atoms as you go down group 7
They get bigger as each element has one extra filled main level of electrons compared to the one before it.
Define electronegativity
Electronegativity is a measure of an atoms ability to attract electrons, or electron density towards itself in a covalent bond.
What is the trend in melting and boiling points as you go down group seven
The melting and boiling points increase because the atoms get bigger/have more electrons so the Van Der Waals forces are stronger.
What is the link between boiling point and volatility for group 7 elements
The lower the boiling point, the more volatile the element.
Explain why the electronegativity of the H—X bond (and halogens in general) decreases as you go down the group
- The shared electrons in the H—X bond get further away from the nucleus as the atoms get larger going down the group.
- This makes the shared electrons further from the halogen nucleus and increases the shielding by more inner shells of electrons.
- These factors are more important than the increasing nuclear charge, so electronegativity decreases down the group.
What is the trend in the oxidising ability of the halogens as you go down the group
The oxidising ability of the halogens decreases as you go down the group
Which halogen is one of the most powerful oxidising agents known
Fluorine.
How do halogens undergo displacement reactions
Halogens with react with metal halides in such a way that the halide in the compound will be replaced with a more reactive halogen, but not by a less reactive one.
When halogens undergo a displacement reaction with a metal halide, what is the oxidising agent
The more reactive halogen that is displacing the less reactive one.
What oxidation state do halogens always have
Halogens always go from an oxidation state of 0 to an oxidation state of -1 when reacting with a metal
What is the trend in the reducing power of a halogen as you go down the group
The reducing power of the halogens increases as you go down the group
How do halide ions act as reducing agents
They lose electrons and become halogen molecules
What type of reaction demonstrates the differing reducing powers of the halogens
The reaction of solid sodium halides with concentrated sulphuric acid
