Group 7 - displacement reactions
A more The tendency of a substance to undergo a chemical reaction. An element placed in group 7 of the periodic table, which starts with fluorine and ends with astatine. The name 'halogen' means 'salt-producing' because halogens produce a range of salts when they react with metals. can Take the place of another substance in a chemical reaction. For example, a metal can displace a less reactive metal from its oxide, removing oxide ions from the less reactive metal and becoming an oxide itself. a less reactive halogen from Mixture formed by a solute and a solvent. of its The substance formed when the hydrogen ion in an acid is replaced by a metal ion.. For example, chlorine is more reactive than iodine. A solution of chlorine can displace iodine from potassium iodide solution:
chlorine + potassium iodide 鈫 potassium chloride + iodine
Cl2(aq) + 2KI(aq) 鈫 2KCl(aq) + I2(aq)
The reaction mixture turns darker as iodine solution forms.
The slideshow shows what happens when solutions of chlorine, bromine and iodine are added to various potassium A halide ion is an ion formed when a halogen atom (an atom from group 7) gains one electron. Halide ions have a single negative charge. Ionic compounds containing halide ions may be called halides. salts.
Image caption, Adding chlorine, bromine and iodine to halogen salts
Chlorine water is added to three solutions
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Question
Write a balanced equation for the displacement reaction of bromine solution with sodium iodide solution.
Br2(aq) + 2NaI(aq) 鈫 2NaBr(aq) + I2(aq)
Question
Can iodine displace chlorine from sodium chloride solution? Explain your answer.
No, because iodine is less reactive than chlorine.
Explaining the trend in reactivity
When a group 7 element takes part in a reaction, its The smallest part of an element that can exist. each gain one Subatomic particle, with a negative charge and a negligible mass relative to protons and neutrons.. These atoms form negatively charged Electrically charged particle, formed when an atom or molecule gains or loses electrons.. The ions have a stable arrangement of electrons, with a complete outer shell.
Going down group 7:
- the atoms become larger
- the outer shell becomes further from the The central part of an atom. It contains protons and neutrons, and has most of the mass of the atom. The plural of nucleus is nuclei.
- the force of attraction between the nucleus and the outer shell decreases
- an outer electron is gained less easily
- the halogen becomes less reactive
The periodic table, containing all the known elements, arranged in groups and periods