11.2 AS Level

The chemical properties of the halogen elements and the hydrogen halides

7 flashcards to master this topic

Key Concept Flip

Describe the trend in oxidising ability of the halogens down Group 17.

Answer Flip

Oxidising ability decreases down the group. This is because atomic radius increases, shielding increases, and nuclear attraction decreases, making it harder to attract an electron to form a negative ion.

Definition Flip

Write a balanced chemical equation for the reaction between chlorine and hydrogen.

Answer Flip

H₂(g) + Cl₂(g) → 2HCl(g). This reaction requires UV light or heat to overcome the high activation energy.

Key Concept Flip

Explain the relative reactivity of halogens with hydrogen down Group 17.

Answer Flip

Reactivity decreases down the group. This is due to the decreasing bond enthalpy of the H-X bond (X = halogen), making it harder to break the bond and form the hydrogen halide.

Key Concept Flip

Describe the trend in thermal stability of the hydrogen halides (HX) down Group 17.

Answer Flip

Thermal stability decreases down the group. This is because the bond enthalpy of the H-X bond decreases as you go down the group, making it easier to break the bond upon heating.

Key Concept Flip

Explain the relationship between H-X bond strength and the thermal stability of hydrogen halides.

Answer Flip

Stronger H-X bonds require more energy to break, resulting in higher thermal stability. Conversely, weaker H-X bonds break more easily, leading to lower thermal stability.

Definition Flip

Arrange the hydrogen halides (HF, HCl, HBr, HI) in order of increasing thermal stability.

Answer Flip

HI < HBr < HCl < HF. This is because the H-F bond is the strongest and the H-I bond is the weakest.

Key Concept Flip

Why does fluorine react more vigorously with hydrogen than iodine does?

Answer Flip

Fluorine reacts more vigorously with hydrogen than iodine because the F-F bond is weaker than the I-I bond, and the H-F bond formed is stronger than the H-I bond. These differences require less energy to react.

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9.3 Chemical periodicity of other elements 11.3 Some reactions of the halide ions