Group 7 - The Halogens | Properties of Matter | Chemistry | FuseSchool

Summary

This script delves into the chemistry of halogens, elements from Group 7 of the periodic table, including fluorine, chlorine, bromine, iodine, and astatine. It highlights their reactivity, physical states, and key reactions such as displacement, interaction with metals to form metal halides, and combination with hydrogen to produce hydrogen halides. The lesson illustrates the reactivity trend within the group and demonstrates how more reactive halogens displace less reactive ones in compounds. It also covers the formation of common compounds like sodium chloride and hydrogen chloride, emphasizing the exothermic nature of these reactions.

Takeaways

• 🌐 Halogens are elements in Group 7 of the periodic table, including fluorine, chlorine, bromine, iodine, and astatine.
• 🚫 Halogens in their elemental form are toxic, but their compounds have various real-life applications.
• 🔋 Halogens have seven electrons in their valence shell and can form an ion with a -1 charge by accepting one electron.
• 📊 Atomic radii, melting points, boiling points, and density of halogens increase as you move down the group.
• 🌬️ Fluorine and chlorine are gases, bromine is a liquid, and iodine and astatine are solids, each with distinct colors.
• ⬇️ Reactivity of halogens decreases as you move down the group, with a more reactive halogen displacing a less reactive one.
• 💧 Displacement reactions of halogens in aqueous solutions demonstrate their reactivity with other halide compounds.
• 🔄 Adding chlorine water to potassium bromide or iodide displaces bromine and iodine, respectively, due to chlorine's higher reactivity.
• 🚫 No displacement reaction occurs when bromine water is added to potassium chloride due to lower reactivity.
• 🌟 Halogens can react with certain metals to form metal halides, such as sodium chloride, commonly known as table salt.
• 🔥 Halogens also react with hydrogen gas to produce hydrogen halides, with most reactions being highly exothermic.

Q & A

What are the elements in Group 7 of the periodic table known as?

The elements in Group 7 of the periodic table are known as halogens.

Name the halogens and describe their physical states at room temperature.

The halogens are fluorine (a very pale green gas), chlorine (a greenish yellow gas), bromine (a reddish brown liquid), iodine (a gray solid that sublimes to a purple vapor), and astatine (a black solid and radioactive).

What is the common characteristic of halogens in terms of their valence electrons?

Halogens all have seven electrons in their valence shell and can accept one electron to form an ion with a -1 charge.

How do the properties of halogens change as you move down the group in the periodic table?

As you move down the group, atomic radii increase by one electron shell, and as a consequence, melting points, boiling points, and density also increase.

Why are halogens in their elemental form considered toxic?

Halogens in their elemental form are toxic due to their highly reactive nature and ability to form ions with a -1 charge.

What happens when chlorine water is added to an aqueous solution of potassium chloride?

No reaction occurs when chlorine water is added to an aqueous solution of potassium chloride because chlorine is more reactive than bromine, and no displacement reaction takes place.

Describe the outcome of adding chlorine water to an aqueous solution of potassium bromide.

When chlorine water is added to an aqueous solution of potassium bromide, chlorine displaces bromine, producing potassium chloride and liberating bromine, resulting in a reddish-brown solution.

What is observed when chlorine water is added to an aqueous solution of potassium iodide?

A displacement reaction occurs, liberating iodine and producing a dark brown solution due to the presence of iodine, since chlorine is more reactive than iodine.

Predict the outcome when bromine water is added to an aqueous solution of potassium chloride.

The solution turns reddish-brown, but no displacement reaction occurs because bromine is less reactive than chlorine.

What happens when bromine water is added to an aqueous solution of potassium bromide?

No reaction occurs because bromine is already present in the compound, and it is not displaced by itself.

Describe the reaction when bromine water is added to an aqueous solution of potassium iodide.

Bromine displaces and liberates iodine in potassium iodide, producing a dark brown solution due to the presence of iodine, as bromine is more reactive than iodine.

Why are no displacement reactions observed when iodine is added to the aqueous solutions of potassium chloride, bromine, and iodide?

No displacement reactions occur because iodine is less reactive than both chlorine and bromine, and thus cannot displace them from their compounds.

How can sodium chloride, or table salt, be produced from its elemental form?

Sodium chloride can be produced from the reaction of heated sodium metal with chlorine gas, resulting in a highly exothermic reaction that forms table salt.

What is the general reaction of halogens with hydrogen gas?

Halogens react with hydrogen gas to produce the corresponding hydrogen halide, with most of these reactions being highly exothermic.

In summary, what are the key reactions of halogens as described in the script?

The key reactions of halogens include displacement reactions where a more reactive halogen displaces a less reactive one in a compound, reactions with metals to produce metal halides, and reactions with hydrogen to produce hydrogen halides.