3.1.3 - The Halogens Flashcards
What are the elements in Group 17 of the periodic table called?
The elements in Group 17 of the periodic table are called the halogens.
What are the elements in the halogen group?
The elements in the halogen group are fluorine (F), chlorine (Cl), bromine (Br), iodine (I), and astatine (At).
What is the trend in the physical state of halogens as you go down Group 17?
The physical state of halogens changes as you go down the group:
- Fluorine is a gas.
- Chlorine is a gas.
- Bromine is a liquid.
- Iodine is a solid.
- Astatine is a solid.
How does the electronegativity of halogens change down Group 17?
Electronegativity decreases down Group 17 because the atomic radius increases, meaning the nucleus has a weaker attraction for bonding electrons.
What is the trend in the atomic radius of halogens as you move down Group 17?
The atomic radius increases as you move down Group 17 because additional electron shells are added, making the atoms larger.
How does reactivity change down Group 17?
Reactivity decreases as you move down Group 17 because the atomic radius increases and the outer electrons are further from the nucleus, making it harder for halogens to attract electrons for reactions.
What is the trend in the melting and boiling points of halogens as you go down the group?
The melting and boiling points increase as you move down the group due to the increasing size and strength of van der Waals forces between molecules.
How does chlorine react with water?
Chlorine reacts with water to form hydrochloric acid (HCl) and hypochlorous acid (HOCl). It also undergoes disproportionation, where one chlorine atom is reduced and another is oxidized.
How does fluorine react with water?
Fluorine reacts explosively with water to form hydrofluoric acid (HF) and oxygen. Fluorine is much more reactive than chlorine due to its smaller atomic size and higher electronegativity.
What is the trend in the oxidizing power of halogens?
The oxidizing power of halogens decreases as you move down the group. Fluorine is the strongest oxidizing agent, while iodine is the weakest.
What happens in a displacement reaction involving halogens?
In a displacement reaction, a more reactive halogen will displace a less reactive halogen from its salt. For example, chlorine displaces bromine or iodine from their salts.
What is the trend in electronegativity as you go down Group 17?
Electronegativity decreases as you go down Group 17 because the atomic radius increases and the ability of the nucleus to attract bonding electrons weakens.
How does halogen displacement work in a solution of sodium halide?
In solution, the more reactive halogen will displace the less reactive halogen from its salt. For example, if chlorine is bubbled through a solution of sodium bromide (NaBr), chlorine will displace bromine and form sodium chloride (NaCl).
What is the trend in color of halogens in aqueous solution?
The color of halogens in aqueous solution changes as you move down the group:
- Fluorine: Pale yellow (gas).
- Chlorine: Greenish-yellow (gas).
- Bromine: Red-brown (liquid).
- Iodine: Dark purple (solid, but forms a violet vapor).
What is hydrogen halide formation?
Hydrogen halides are formed when halogens react with hydrogen. For example:
- HCl (hydrogen chloride), HBr (hydrogen bromide), and HI (hydrogen iodide) form when the halogens react with hydrogen gas.
How do halogens react with metals?
Halogens react with metals to form metal halides. For example:
- 2Na + Cl₂ → 2NaCl (sodium chloride).
What is the trend in bond strength of halogens as you go down Group 17?
The bond strength of halogens decreases down the group. For example, the bond between H-F is much stronger than H-I, making it harder to break the bond in hydrogen fluoride (HF) than in hydrogen iodide (HI).
What is the trend in bond dissociation enthalpy down Group 17?
Bond dissociation enthalpy decreases as you move down Group 17. This means that it requires less energy to break the bond in I₂ than in Cl₂ or F₂.
What is chlorine bleaching?
Chlorine acts as a bleaching agent when it reacts with water, forming hypochlorous acid (HOCl), which has oxidizing properties that bleach substances.
How is bromine used in organic chemistry?
Bromine is often used in organic chemistry for the electrophilic addition to alkenes, where it adds across the double bond, forming a dibromoalkane.
What is the trend in boiling point of halogens?
The boiling point increases as you go down Group 17 due to the increasing size and mass of the molecules, which leads to stronger van der Waals forces.
How does astatine behave compared to other halogens?
Astatine (At) is the least studied halogen due to its radioactivity. It is predicted to be more metallic and less reactive than iodine, though its exact chemical properties are still under investigation.
What is the disproportionation reaction of chlorine in water?
Chlorine undergoes disproportionation in water, forming both hydrochloric acid (HCl) and hypochlorous acid (HOCl):
Cl2+H2O→HCl+HOCl
How do halogens act as oxidizing agents?
Halogens act as strong oxidizing agents because they readily accept electrons to form halide ions (e.g., Cl⁻, Br⁻, I⁻).
What is the trend in halogen reactivity in displacement reactions?
The reactivity of halogens decreases as you go down Group 17, meaning that fluorine is the most reactive and can displace all the other halogens, while iodine is the least reactive and can only displace bromine and chlorine.
