1- We Ask You Kindly to Go Through the Below Listed Topics of Inorganic Chemistry and To

Notes:

1- We ask you kindly to go through the below listed topics of Inorganic Chemistry and to concentrate on the

main concepts and outlines i.e. you don’t need to learn by heart all texts, figures and tables, it is just to

give you a sufficient explanation for the different topics and to deepen your understanding to the material.

2- Please notify, for the interview, if you choose chemistry instead of physics then you need to study all the

below listed topics and concentrate on at least three topics.

3- Please notify that Inorganic Chemistry part is belonging to chemistry subject .

4- Applicant has to choose either (biology and chemistry) or (biology and physics) for the oral part of the

entrance examination.

INORGANIC CHEMISTRY

Hydrogen and oxygen. Compounds of hydrogen and oxygen.

The halogens. Compounds of the halogens.

Noble gases.

Nitrogen, phosphorous, sulfur and their compounds.

Carbon, allotropic forms of carbon, inorganic carbon compounds.

The s- and p-block metals, transition metals.

Answers of the above-listed topics:

Hydrogen and hydrogen compounds

Oxygen and oxygen compounds

Halogens

Nobel gases

Nitrogen

Nitrogen is a nonmetal, with an electronegativity of 3.04.[10] It has five electrons in its outer shell and is, therefore, trivalent in most compounds. The triple bond in molecular nitrogen (N2) is one of the strongest. The resulting difficulty of converting N2 into other compounds, and the ease (and associated high energy release) of converting nitrogen compounds into elemental N2, have dominated the role of nitrogen in both nature and human economic activities.

At atmospheric pressure, molecular nitrogen condenses (liquefies) at 77K (−195.79°C) and freezes at 63K (−210.01°C)into the beta hexagonal close-packed crystal allotropic form. Below 35.4K (−237.6°C) nitrogen assumes the cubic crystal allotropic form (called the alpha phase). Liquid nitrogen, a fluid resembling water in appearance, but with 80.8% of the density (the density of liquid nitrogen at its boiling point is 0.808 g/mL), is a common cryogen.

Nitrogen compounds

The main neutral hydride of nitrogen is ammonia (NH3), although hydrazine (N2H4) is also commonly used. Ammonia is more basic than water by 6 orders of magnitude. In solution ammonia forms the ammoniumion (NH+4). Liquid ammonia (boiling point 240K) is amphiprotic (displaying either Brønsted-Lowry acidic or basic character) and forms ammonium and the less common amide ions (NH−2); both amides and nitride (N3−) salts are known, but decompose in water. Singly, doubly, triply and quadruply substituted alkyl compounds of ammonia are called amines (four substitutions, to form commercially and biologically important quaternary amines, results in a positively charged nitrogen, and thus a water-soluble, or at least amphiphilic, compound). Larger chains, rings and structures of nitrogen hydrides are also known, but are generally unstable.

Other classes of nitrogen anions (negatively charged ions) are the poisonous azides (N−3), which are linear and isoelectronic to carbon dioxide, but which bind to important iron-containing enzymes in the body in a manner more resembling cyanide. Another molecule of the same structure is the colorless and relatively inert anesthetic gas Nitrous oxide (dinitrogen monoxide, N2O), also known as laughing gas. This is one of a variety of nitrogen oxides that form a family often abbreviated as NOx. Nitric oxide (nitrogen monoxide, NO), is a natural free radical used in signal transduction in both plants and animals, for example, in vasodilation by causing the smooth muscle of blood vessels to relax. The reddish and poisonous nitrogen dioxide NO2 contains an unpaired electron and is an important component of smog. Nitrogen molecules containing unpaired electrons show a tendency to dimerize (thus pairing the electrons), and are, in general, highly reactive. The corresponding acids are nitrous HNO2 and nitric acid HNO3, with the corresponding salts called nitrites and nitrates.

The higher oxides dinitrogen trioxide N2O3, dinitrogen tetroxide N2O4 and dinitrogen pentoxide N2O5, are unstable and explosive, a consequence of the chemical stability of N2. Nearly every hypergolic rocket engine uses N2O4 as the oxidizer; their fuels, various forms of hydrazine, are also nitrogen compounds. These engines are extensively used on spacecraft such as the space shuttle and those of the Apollo Program because their propellants are liquids at room temperature and ignition occurs on contact without an ignition system, allowing many precisely controlled burns. Some launch vehicles such as the Titan II and Ariane 1 through 4 also use hypergolic fuels, although the trend is away from such engines for cost and safety reasons. N2O4 is an intermediate in the manufacture of nitric acid HNO3, one of the few acids stronger than hydronium and a fairly strong oxidizing agent.

Nitrogen is notable for the range of explosively unstable compounds that it can produce. Nitrogen triiodide NI3 is an extremely sensitive contact explosive. Nitrocellulose, produced by nitration of cellulose with nitric acid, is also known as guncotton. Nitroglycerin, made by nitration of glycerin, is the dangerously unstable explosive ingredient of dynamite. The comparatively stable, but less powerful explosive trinitrotoluene (TNT) is the standard explosive against which the power of nuclear explosions are measured

Nitrogen can also be found in organic compounds. Common nitrogen functional groups include: amines, amides, nitro groups, imines, and enamines

Sulfur

Sulfur is a chemical element with symbolS and atomic number15. It is an abundant, multivalentnon-metal. Under normal conditions, sulfur atoms form cyclic octatomic molecules with chemical formula S8. Elemental sulfur is a bright yellow crystalline solid when at room temperature. Chemically, sulfur can react as either an oxidant or reducing agent. It oxidizes most metals and several nonmetals, including carbon, which leads to its negative charge in most organosulfur compounds, but it reduces several strong oxidants, such as oxygen and fluorine.

Sulfur occurs naturally as the pure element (native sulfur) and as sulfide and sulfate minerals.

Sulfur is an essential element for all life, and is widely used in biochemical processes. In metabolic reactions, sulfur compounds serve as both fuels (electron donors) and respiratory (oxygen-alternative) materials (electron acceptors). Sulfur in organic form is present in the vitamins biotin and thiamine, the latter being named for the Greek word for sulfur. Sulfur is an important part of many enzymes and in antioxidant molecules like glutathione and thioredoxin. Organically bonded sulfur is a component of all proteins, as the amino acidscysteine and methionine.

Sulfur compounds

1- Sulfides

Treatment of sulfur with hydrogen gives hydrogen sulfide. When dissolved in water, hydrogen sulfide is mildly acidic:

H2S HS– + H+

Reduction of elemental sulfur gives polysulfide, which consist of chains of sulfur atoms terminated with S– centers:

2 Na + S8 → Na2S8

Ultimately reduction of sulfur gives sulfide salts:

16 Na + S8 → 8 Na2S

2- Oxides and oxyanions

The principal sulfur oxides are obtained by burning sulfur:

S + O2 → SO2

2 SO2 + O2 → 2 SO3

Other oxides are known, e.g. sulfur monoxide and disulfur mono- and dioxides, but they are unstable.

The sulfur oxides form numerous oxyanions with the formula SOn2–. Sulfur dioxide and sulfites (SO2−3) are related to the unstable sulfurous acid (H2SO3). Sulfur trioxide and sulfates (SO2−4) are related to sulfuric acid. Sulfuric acid and SO3 combine to give oleum, a solution of pyrosulfuric acid (H2S2O7) in sulfuric acid.

Peroxides convert sulfur into unstable such as S8O, a sulfoxide. Peroxymonosulfuric acid (H2SO5) and peroxydisulfuric acids (H2S2O8), made from the action of SO3 on concentrated H2O2, and H2SO4 on concentrated H2O2 respectively.

The sulfate anion, SO2−4

Thiosulfate salts (S2O2−3), sometimes referred as "hyposulfites", used in photographic fixing (HYPO) and as reducing agents, feature sulfur in two oxidation states. Sodium dithionite, (S2O2−4), contains the more highly reducing dithionite anion. Sodium dithionate (Na2S2O6) is the first member of the polythionic acids (H2SnO6), where n can range from 3 to many.

3- Halides and oxyhalides

The two main sulfur fluorides are sulfur hexafluoride, a dense gas used as nonreactive and nontoxic propellant, and sulfur tetrafluoride, a rarely used organic reagent that is highly toxic. Their chlorinated analogs are sulfur dichloride and sulfur monochloride. Sulfuryl chloride and chlorosulfuric acid are derivatives of sulfuric acid; thionyl chloride (SOCl2) is a common reagent in organic synthesis

Phosphorous

Phosphorus is a nonmetallicchemical element with symbolP and atomic number15. phosphorus as a mineral is almost always present in its maximally oxidised state, as inorganic phosphate rocks. Elemental phosphorus exists in two major forms—white phosphorus and red phosphorus—but due to its high reactivity, phosphorus is never found as a free element on Earth.

The vast majority of phosphorus compounds are consumed as fertilisers. Other applications include the role of organophosphorus compounds in detergents, pesticides and nerve agents, and matches.

Phosphorus is essential for life. As phosphate, it is a component of DNA, RNA, ATP, and also the phospholipids that form all cell membranes.

Inorganic phosphate rock, which is partially made of apatite (an impure tri-calcium phosphate mineral), is today the chief commercial source of this element.

Phosphorous compounds

Oxoacids of phosphorus

Phosphorous oxoacids are extensive, often commercially important, and sometimes structurally complicated. They all have acidic protons bound to oxygen atoms and some have nonacidic protons that are bonded directly to phosphorus. Although many oxoacids of phosphorus are formed, only nine are important, and three of them, hypophosphorous acid, phosphorous acid, and phosphoric acid, are particularly important ones.

Phosphorus(V) compounds

Oxides

The most prevalent compounds of phosphorus are derivatives of phosphate (PO43-), a tetrahedral anion. Phosphate is the conjugate base of phosphoric acid, which is produced on a massive scale for use in fertilisers. Being triprotic, phosphoric acid converts stepwise to three conjugate bases:

H3PO4 + H2O H3O+ + H2PO4−Ka1= 7.25×10−3

H2PO4− + H2O H3O+ + HPO42−Ka2= 6.31×10−8

HPO42− + H2O H3O+ + PO43−Ka3= 3.98×10−13

Phosphate exhibits the tendency to form chains and rings with P-O-P bonds. Many polyphosphates are known, including ATP. Polyphosphates arise by dehydration of hydrogen phosphates such as HPO42- and H2PO4-. For example, the industrially important trisodium triphosphate (also known as sodium tripolyphosphate, STPP) is produced industrially on a megatonne scale via this condensation reaction:

2 Na2[(HO)PO3] + Na[(HO)2PO2] → Na5[O3P-O-P(O)2-O-PO3] + 2 H2O

Phosphorus pentoxide (P4O10) is the acid anhydride of phosphoric acid, but several intermediates are known between the two. This waxy white solid reacts vigorously with water.

The tetrahedral structure of P4O10 and P4S10.

With metal cations, phosphate forms a variety of salts. These solids are polymeric, featuring P-O-M linkages. When the metal cation has a charge of 2+ or 3+, the salts are generally insoluble, hence they exist as common minerals. Many phosphate salts are derived from hydrogen phosphate (HPO42-).

PCl5 and PF5 are common compounds. Both are volatile and pale or colourless. The other two halides, PBr5 and PI5PI5 are unstable. The pentachloride and pentafluoride adopt trigonal bipyramid molecular geometry and are Lewis acids. With fluoride, PF5 forms PF6–, an anion that is isoelectronic with SF6. The most important oxyhalide is phosphorus oxychloride (POCl3), which is tetrahedral.

Before extensive computer calculations were feasible, it was proposed that bonding in phosphorus(V) compounds involved d orbitals. It is now accepted that the bonding can be better explained by molecular orbital theory and involves only s- and p-orbitals on phosphorus.

Phosphorus(III) compounds

Phosphine (PH3) and its organic derivatives (PR3) are structural analogues with ammonia (NH3) but the bond angles at phosphorus are closer to 90° for phosphine and its organic derivatives. It is an ill-smelling, toxic compound. Phosphine is produced by hydrolysis of calcium phosphide, Ca3P2. Unlike ammonia, phosphine is oxidised by air. Phosphine is also far less basic than ammonia.

All four symmetrical trihalides are well known: gaseous PF3, the yellowish liquids PCl3 and PBr3, and the solid PI3. These materials are moisture sensitive, hydrolysing to give phosphorus acid. The trichloride, a common reagent, is produced by chlorination of white phosphorus:

P4 + 6 Cl2 → 4 PCl3

The trifluoride is produced by from the trichloride by halide exchange. PF3 is toxic because it binds to haemoglobin.

Phosphorus(III) oxide, P4O6 (also called tetraphosphorus hexoxide) is the anhydride of P(OH)3, the minor tautomer of phosphorous acid. The structure of P4O6 is like that of P4O10 less the terminal oxide groups.

Mixed oxyhalides and oxyhydrides of phosphorus(III) are almost unknown

Carbon and allotropic forms of carbon

Carbon is a nonmetallic element, represented by the symbol 'C' and has an atomic number 14. Hence, if you take a look at the modern periodic table, you will find carbon in amongst the group 14 elements. Chemically, it is a highly stable element. As far as availability of carbon in the Earth's crust is concerned, it stands 15th in the most abundant elements list. When calculated in percentage value of mass, it is found as the 4th most abundant chemical element in the whole universe.
allotropes: structures have the same chemical properties but different physical properties
Carbon Allotropes:
As mentioned already, the element carbon can exist in varied molecular configurations. Out of these, the three allotropes of carbon are found abundant in nature. These include graphite, diamond and amorphous carbon. They are formed when carbon is subjected to different conditions. Say for example; carbon occurs as soft graphite under normal pressure, while it takes the form of diamond when exposed to very high pressure. The types of crystals system in graphite are hexagonal, while that of diamond is isometric. Following is a detailed information regarding allotropic forms of carbon:
Graphite
Researches have opined that graphite is formed when carbon is exposed to normal pressure condition. Considering this, opaque carbon is the most stable allotrope under normal conditions. It is soft, lightweight and has the property to conduct electricity. It cleaves in smooth planes; the main reason being bonding of graphite flakes by weak van der Waals force. Commercially, graphite is used as a lubricant. When subjected to very high temperature and pressure, graphite can be converted into diamond.
Diamond
Diamond, the most precious stone, is an allotrope of carbon. Its high value in jewelry is a result of unique light dispersion. Unlike graphite, it is transparent, compact and abrasive in nature. It is the hardest and strongest known mineral, used for commercial applications like cutting, drilling and grinding. Diamond cannot conduct electricity; rather it is described as a good insulator. At present, scientific studies are ongoing to produce synthetic diamonds in laboratories.