What is the valence electron configuration of the halogens? Why do the boiling points and melting points of the halogens increase steadily from F 2 to I 2 ? Give two reasons why F 2 is the most reactive of the halogens. Explain why the boiling point of HF is much higher than the boiling points of HCI, HBr, and HI. In nature, the halogens are generally found as halide ions in various minerals and seawater. What is a halide ion, and why are halide salts so stable? The oxidation states of the halogens vary from −1 to +7. Identify compounds of chlorine that have −1, +1, +3, +5, and +7 oxidation states.

Interpretation: The valence electron configuration for halogens is to be stated. The reason for the increase in the melting and boiling point from F2 to I2 . Two reasons are to be stated for high reactivity of F2 among other halogens. The reason for the fact, the boiling point of HF is much higher than the boiling points of HCl, HBr , and HI . The definition of halide ions and explanation for the stability of halide ions is to be stated. The compounds of chlorine that have −1, +1, +3, +5 and +7 oxidation states are to be stated.

Concept introduction: Halogen elements are highly reactive. All are nonmetals. They form hydrides when react with hydrogen.

To determine: The valence electron configuration for halogens; the reason for the increase in the melting and boiling point from F2 to I2 ; two reasons for high reactivity of F2 among other halogens; the reason for the fact, the boiling point of HF is much higher than the boiling points of HCl, HBr , and HI ; the definition of halide ions and explanation for the stability of halide ions; the compounds of chlorine that have −1, +1, +3, +5 and +7 oxidation states.

Explanation

The valence electron configuration for halogens is ns2np5 .

The common halogen elements are,

• Fluorine
• Chlorine
• Bromine
• Iodine

The valence electron configuration for halogens is ns2np5 .

Explanation

Melting and boiling point increases from F2 to I2 due to increase in the bond strength.

The melting and boiling point of halogens depend on bond strength X−X (where X is halogen atoms). Higher the bond strength, higher will be the melting and boiling point. Since, bond strength increases down the group. Therefore, melting and boiling point increases from F2 to I2 .

Explanation

The molecule F2 is most reactive because the size of F2 is very small and the energy of F−F bond is low.

The molecule F2 is most reactive due to the following reasons,

• The size of F2 is very small as compared to other halogens.
• The energy of F−F bond is low due to non-bonding electrons in this molecule.

The boiling point of HF is much higher than the boiling points of HCl, HBr , and HI because Fluorine has the ability to form hydrogen bond.

The boiling point of compound is said to be high if it can form hydrogen bonds.

The electronegativity of halogen atoms decreases down the group. Fluorine molecule is most electronegative. Due to high electronegativity, F2 molecule easily forms hydrogen bonds. On the other hand, electronegativity of other halogen groups is very small that makes them unable to form hydrogen bonds.

The boiling point of HF is much higher than the boiling points of HCl, HBr , and HI because Fluorine has the ability to form hydrogen bond.

Addition of an electron to hydride yields halide ion (X−) . Halide salts are stable because they obtain inert gas electron configuration.

The combination of hydrogen (H) with halogens (X) forms hydrides. The reaction is,

X2+H2→2HX

Addition of an electron to hydride yields halide ion (X−) . The reaction is,

X+e−→X−

Halide salts are stable because they obtain inert gas electron configuration.

The compounds of chlorine that have −1, +1, +3, +5 and +7 oxidation states are,

HCl, Cl2O, Cl2O3, Cl2O5 and Cl2O7

The compounds of chlorine that have −1, +1, +3, +5 and +7 oxidation states are,

The compound of Chlorine that has −1 oxidation state is HCl , that is,

In HCl , the oxidation state of Hydrogen atom (H) is +1 .

It is assumed that oxidation state of Chlorine (Cl) is x .

The given compound contains single Hydrogen and Chlorine atom. Since, overall charge on stable compound is zero. Therefore,

1+x=0x=−1

Therefore, the oxidation state of Chlorine in HCl is −1