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Posted by Dgf Chd 5 years, 2 months ago (4635669)
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Posted by Dgf Chd 5 years, 2 months ago (4635669)
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Yogita Ingle 5 years, 2 months ago (2577571)
Halogens are coloured because of their low ionisation energy.
As a result, the electrons get excited in the visible region of light.
The remaining light falls in the visible region and halogens appear to be coloured.
For example: Fluorine absorbs wavelengths corresponding to violet light and the remaining light appears to be yellow. Thus, fluorine has a yellow colour. Similarly, chlorine is greenish yellow, bromine reddish and iodine is a violet solid.
Devil ? 5 years, 2 months ago (3139322)
Posted by Dgf Chd 5 years, 2 months ago (4635669)
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Yogita Ingle 5 years, 2 months ago (2577571)
The molecules of each substance attract each other through dispersion (London) intermolecular forces. Whether a substance is a solid, liquid, or gas depends on the balance between the kinetic energies of the molecules and their intermolecular attractions
In fluorine, the electrons are tightly held to the nuclei. The electrons have little chance to wander to one side of the molecule, so the London dispersion forces are relatively weak
As we move from fluorine to iodine, the electrons are further from the nuclei so the electron clouds can more easily distort. The London dispersion forces become progressively stronger.
At a low enough temperature, the molecules will all be solids. At a high enough temperature, they will all be gases.
It is only at a temperature between −7oC and 59o that fluorine and chlorine are gases, bromine is a liquid and iodine is a solid.
Posted by Dgf Chd 5 years, 2 months ago (4635669)
- 2 answers
Yogita Ingle 5 years, 2 months ago (2577571)
The molecules of each substance attract each other through dispersion (London) intermolecular forces. Whether a substance is a solid, liquid, or gas depends on the balance between the kinetic energies of the molecules and their intermolecular attractions
In fluorine, the electrons are tightly held to the nuclei. The electrons have little chance to wander to one side of the molecule, so the London dispersion forces are relatively weak
As we move from fluorine to iodine, the electrons are further from the nuclei so the electron clouds can more easily distort. The London dispersion forces become progressively stronger.
At a low enough temperature, the molecules will all be solids. At a high enough temperature, they will all be gases.
It is only at a temperature between −7oC and 59o C that fluorine and chlorine are gases, bromine is a liquid and iodine is a solid.
Posted by Dgf Chd 5 years, 2 months ago (4635669)
- 1 answers
Yogita Ingle 5 years, 2 months ago (2577571)
- Oxidation states: They show variable oxidation states like:
Fluorine: -1
Chlorine: -1, +1, +3, +7
Bromine : -1, +1, +3, +5, +7
Iodine: -1, +1, +3, +5, +7
- Higher oxidation states of halogens are used when they are combining with small size highly electronegative ions.
- All halogens are very reactive and reactivity decreases down the group.
- All act as Lewis acids as they accept electron.
- Fluorine is the strong oxidizing agent among all.
Posted by Navya Singh 5 years, 2 months ago (8888269)
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Posted by Dgf Chd 5 years, 2 months ago (4635669)
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Yogita Ingle 5 years, 2 months ago (2577571)
Preparation of Sulphur Dioxide
1. In the laboratory, sulphur dioxide is prepared by the reaction of metallic sulphite or a metallic bisulphite with dilute acid. For example, a reaction between the dilute sulphuric acid and sodium sulphite will result in the formation of SO2.
Na2SO3 + H2SO4 → Na2SO4 + H2O + SO2
2. Commercially it is obtained as a by-product released from the roasting of sulphide ores. The gas obtained is dried, liquefied and then stored in steel cylinders.
4FeS2 (s) + 11 O2 (g) →2Fe2O3 (s) + 8SO2 (g)
Posted by Dgf Chd 5 years, 2 months ago (4635669)
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Yogita Ingle 5 years, 2 months ago (2577571)
Electron gain enthalpy:
- Along period it is more negative because of attraction towards electron as of increased nuclear charge.
- Down the group electron gain enthalpy keeps on becoming less negative because nuclear charge decreases and size.
- So, the group 17 has highest electron gain enthalpy due to smallest size in periodic table.
- Please note that: Fluorine has less electron gain enthalpy than chlorine because due to small size of oxygen the incoming electron suffers repulsion therefore, electron gain enthalpy is less negative as compared to chlorine.
Posted by Dgf Chd 5 years, 2 months ago (4635669)
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Yogita Ingle 5 years, 2 months ago (2577571)
Fluorine is the most electronegative element and cannot exhibit any positive oxidation state. Other halogens have d orbitals and therefore, can expand their octets and show + 1, + 3, + 5 and + 7 oxidation states also.
Tanya ?? 5 years, 2 months ago (9516882)
Posted by Dgf Chd 5 years, 2 months ago (4635669)
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Yogita Ingle 5 years, 2 months ago (2577571)
Fluorine is the most electronegative element and cannot exhibit any positive oxidation state. Other halogens have d orbitals and therefore, can expand their octets and show + 1, + 3, + 5 and + 7 oxidation states also.
Posted by Dgf Chd 5 years, 2 months ago (4635669)
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Posted by Dgf Chd 5 years, 2 months ago (4635669)
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Meghna Thapar 5 years, 2 months ago (6237)
Oxidation state indicates the degree of oxidation for an atom in a chemical compound; it is the hypothetical charge that an atom would have if all bonds to atoms of different elements were completely ionic. Oxidation states are typically represented by integers, which can be positive, negative, or zero.
- The oxidation number of a free element is always 0.
- The oxidation number of a monatomic ion equals the charge of the ion.
- The oxidation number of H is +1, but it is -1 in when combined with less electronegative elements.
- The oxidation number of O in compounds is usually -2, but it is -1 in peroxides.
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Posted by Kashish Kumari 🙂 5 years, 2 months ago (9926139)
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Yogita Ingle 5 years, 2 months ago (2577571)
| Xylem | Phloem |
| 1. It conducts water and minerals from roots to leaves. | 1. It conducts food from leaves to all parts of the plant. |
| 2. It is composed of mainly dead elements. | 2. It is composed of mainly living elements. |
| 3. Transport is unidirectional. | 3. Transport is bidirectional. |
| 4. It has four types of cells: Tracheids, Vessels, Xylem parenchyma and Xylem fibres. | 4. It has four types of cells: Phloem fibres, Sieve tubes, Companion cells and Phloem parenchyma. |
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Posted by Dgf Chd 5 years, 2 months ago (4635669)
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Yogita Ingle 5 years, 2 months ago (2577571)
The nuclear and atomic radii of these elements keep on increasing as we move down the group. This happens because of the addition of an extra energy level. They have the minimal atomic radii compared to the other elements in the related periods. This can be attributed to the fact that their atomic charge is quite powerful.
Posted by Dgf Chd 5 years, 2 months ago (4635669)
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Yogita Ingle 5 years, 2 months ago (2577571)
- Physical state: The group 17 elements are found in diverse physical states. For example, Fluorine and Chlorine are gases. On the other hand, Bromine is a liquid and Iodine is solid.
- Colour: These elements have a variety of colours. For example, while Fluorine is pale yellow in colour, Iodine is dark violet in colour.
- Solubility: Florine and Chlorine are soluble in water. On the other hand, Bromine and Iodine are very less soluble in water.
- Melting and boiling points: Melting and boiling points of these elements increase as we move down the group from Fluorine to Iodine. Thus, Fluorine has the lowest boiling and melting points.
Posted by Dgf Chd 5 years, 2 months ago (4635669)
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Yogita Ingle 5 years, 2 months ago (2577571)
- Electronic configuration-The general electronic configuration for this group is ns2np5
- Fluorine (F) [He]2s2,2p5
- Chlorine (Cl) [Ne]3s2,3p5
- Bromine(Br)[Ar]3d104s24p5
- Iodine (I)[Kr]4d10,5s2,5p4
- Astatine (At) [Xe]4f14,5d10,6s2,6p4
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Yogita Ingle 5 years, 2 months ago (2577571)
Halogens are coloured because of their low ionisation energy.
As a result, the electrons get excited in the visible region of light.
The remaining light falls in the visible region and halogens appear to be coloured.
For example: Fluorine absorbs wavelengths corresponding to violet light and the remaining light appears to be yellow. Thus, fluorine has a yellow colour. Similarly, chlorine is greenish yellow, bromine reddish and iodine is a violet solid.
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