7211090
Description
Flashcards by Nancy Mathew, updated more than 1 year ago
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Created by Nancy Mathew
over 7 years ago
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| Question | Answer |
| What are O, S, Se, Te, Po commonly called? | |
| Naturally existing sulphates | Gypsum - CaSO4.2H20 Epsom Salt - MgSO4.7.H20 Baryte - BaSO4 |
| Naturally occurring SULPHIDES | Galena - PbS Zinc blende - ZnS Copper pyrites - CuFeS2 |
| General electronic configuration | ns2 np4 (6 valence electrons) |
| Atomic/ Ionic radii | Increases down the group (more shells) |
| Ionisation enthalpy (energy to remove an e-) | Decreases down the group lesser than gr 15 (1/2-filled p-orbitals) |
| Electron gain enthalpy (energy to gain an e-) | More negative to less negative |
| Why is the electron gain enthalpy of oxygen less (-ve) than sulphur? | Compact nature of oxygen atom |
| Electronegativity (ability to pull an e- pair towards itself) | Decreases down the group (hence metallic character increases from O to Po) |
| Metallic character | O, S - Non-metals Se, Te - Metalloids Po - Metal |
| Radioactive element(s) | Polonium |
| Melting and boiling points (trend) | Increase down the group (increase in size) |
| Why is there a large difference between the melting and boiling points of Oxygen and Sulphur? | Due to difference in atomicity Oxygen - O2 (diatomic) Sulphur - S8 (Polyatomic) |
| Oxidation states exhibited | -2 - stability decreases down the group +2 +4 - stability increases down the group (inert pair effect) - covalent bonding +6 - stability decreases down the group - covalent bonding |
| When does oxygen exhibit +2 oxidation state? | Oxygen has high electronegativity, hence exhibits negative ox. states (-2) In OF2 - +2 |
| Oxidation states of S, Se, Te with O, F | with oxygen - +4 with fluorine - +6 |
| Anomalous behaviour of oxygen is due to... | 1. Small size 2. High electronegativity |
| Why is there strong hydrogen bonding in H2O, but not in H2S? (H2O is liquid while H2S is gaseous) | 1. Small size 2. High electronegativity |
| Covalency of Oxygen, reason | Limited to 4 Absence of d-orbitals |
| Hydrides and their trends | H2O, H2S, H2Se, H2Te, H2Po 1. Acidity -> (decrease in bond dissociation enthalpy, more ability to release H+) 2. Thermal stability -> '' 3. Strength of reducing agent -> (except H2O) |
| Types of oxides | EO2 - reducing strength decreases down the group (SO2 reducing, TeO2 - oxidising) EO3 - S, Se, Te (both are acidic in nature) |
| Halides | EX2, EX4, EX6 |
| Stability of halides | stability - F > Cl > Br > I |
| stable hexahalides and their structure | hexafluorides , octahedral SF6 is most stable (steric reasons) |
| Structure and hybridisation of tetrafluorides | sp3d - Trigonal bipyramidal with one lp in the equatorial position (SEE - SAW) |
| Dichlorides, dibromides Structure, hybridisation | Hybridisation: sp3 Structure: Tetrahedral DIMERIC in nature (S2F2, S2Cl2, S2Br2, Se2Cl2, Se2Br2) |
| Disproportionation in dimeric halides | +2 +4 0 2Se2Cl2 ->SeCl4 +3Se |
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