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We have daily contact with many transition metals. Iron occurs everywhere—from the rings in your spiral notebook and the cutlery in your kitchen to automobiles, ships, buildings, and in the hemoglobin in your blood.
- 23.1: General Properties of Transition Metals
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- d and f block elements class 12 ppt
Chapter summaryIntroductionCharacteristic properties of the s-block elements. Variation in properties of the s-block elementsof the First Group Alkali Metals. Physical Properties.
Uploaded by. Physics Class 12 Notes. It comprises two electron conductors which are separated by an ionic conductor and are linked by an electron conductor.
23.1: General Properties of Transition Metals
Chapter summaryIntroductionCharacteristic properties of the s-block elements. Variation in properties of the s-block elementsof the First Group Alkali Metals. Physical Properties. Characteristic properties of s-block elementsMetallic characterLow electronegativityBasic oxides, hydroxidesIonic bond with fixed oxidation statesCharacteristic flame coloursWeak tendency to from complex.
Metallic characterHigh tendency to lose e- to form positive ionsMetallic character increases down both groups. ElectronegativityLow nuclear attraction for outer electronsHighly electropositiveSmall electronegativity. Variation in properties of elementsAtomic radiiIonization enthalpiesHydration enthalpiesMelting pointsReactions with oxygen, water, hydrogen and chlorine. Removal of a 2nd electron is much more difficult because it involves the removal of inner shell electron.
As atomic radius increases, the outer e is further away from the well-shielded nucleus. Hydration EnthalpyGeneral trends:On going down both groups, hydration enthalpy decreases. As the ions get larger, the charge density of the ions decreases, the electrostatic attraction between ions and water molecules gets smaller.
Group 2 ions have hydration enthalpies higher than group 1. Group 2 cations are doubly charged and have smaller sizes. Ionization EnergyAmount of energy required to remove an electron from the ground state of a gaseous atom or ion.
First ionization energy is that energy required to remove first electron. Second ionization energy is that energy required to remove second electron, etc. Trends in First Ionization EnergiesAs one goes down a column, less energy is required to remove the first electron. For atoms in the same group, Zeff is essentially the same, but the valence electrons are farther from the nucleus. Ionization Enthalpy of Alkali Metalsionization enthalpy decreases down the group from Li to cs because as we move down a group the number of valence electrons goes increasing separating the electrons away from the nucleus ,there is an increasing shielding of the nuclear charge by the inner shell electrons and thus the removal of electrons requires less energy as we move down.
All alkali group 1 metals react violently with water, forming Hydrogen gas and Hydroxides pH above 7 :. Alkali metals are:Metals found in group 1 of the periodic table. Soft when cut compared to other metals. Metals with low melting points and densities. Powerful reducing agent and form univalent compounds. Metals which tarnish in air. The alkali metals combine directly with halogens under appropriate conditions forming halides of general formula MX.
These halides can also be prepared by the action of aqueous halogen acids HX on metals oxides, hydroxides or carbonate. All these halides are colourless, high melting crystalline solids having high negative enthalpies of formation. Since the alkali metals are highly electropositive, therefore their hydroxides are very strong bases and hence they form salts with all oxoacids. The carbonates M2CO3 of alkali metals are remarkably stable upto K, above which they first melt and then eventually decompose to form oxides.
Crude sodium chloride, generally obtained by crystallisation of brine solution, contains sodium sulphate, calcium sulphate, calcium chloride and magnesium chloride as impurities.
Calcium chloride,CaCl2, and magnesium chloride MgCl2 are impurities because they are deliquescent absorb moisture from the atmosphere. To obtain pure sodium chlorideCrude salt is dissolved in minimum amount of water and filtered to remove insoluble impurities. The solution is then saturated with hydrogen chloride gas. Crystals of pure sodium separate out. Calcium and magnesium chloride, being more soluble than sodium chloride, remains in solution.
A brine soln. Sodium metal discharged at the cathode combines with mercury to form sodium amalgam. Chlorine gas is evolved at the anode. NaOH is a white, translucent solid and it melts at K.
Crystals of NaOH are deliquescent. USES- The manufacture of soap, paper and no. In petroleum refiningIn textile industry for mercerising cotton fabricsAs laboratory reagentFor preparation of pure oils and fats.
It is made by saturating a solution of sodium carbonate with carbon dioxide. The white crystalline powder of sodium hydrogencarbonate , being less soluble, gets separated out.
Potassium ions are present in higher concentration inside the cells than sodium ions and they are present outside the cell in blood plasma. Because of large concentration gradient inside and outside the cells, the transport of sodium ion into the cells is favoured.
To pump out these ions again from the cell to maintain concentration gradient large driving force is carried out. The energy for this process is provided by ATP molecules. Thus both sodium and potassium ions are essential for living organisms. LithiumSymbol LiAtomic no. Much harder than other alkali metals. Reacts with oxygen least readily to form normal oxide E. Li2O , whereas other alkali metals form peroxides and superoxides E. The carbonates, hydroxides and nitrates of lithium decompose on heating unlike those of other alkali metals which are somewhat stable towards heat.
Log in Get Started. TAGS: removal of electrons g na g sblock elementsof inner shell electrons hydration enthalpy decreases number of valence electrons ionization energiesas wellshielded nucleus. Download for free Report this document.
Embed Size px x x x x Chapter summary. Introduction Characteristic properties of the s-block elements. Variation in properties of the s-block elements of the First Group Alkali Metals. IA IIA.
Group 2 cations are doubly charged and have smaller sizes Ionization EnergyAmount of energy required to remove an electron from the ground state of a gaseous atom or ion. In order of increasing atomic number the alkali metals are: LithiumSodiumPotassiumRubidium CaesiumFrancium Increasing atomic number All alkali group 1 metals react violently with water, forming Hydrogen gas and Hydroxides pH above 7 : Alkali metals are:Metals found in group 1 of the periodic table.
On cumbustion in excess of air, alkali metals form Oxides- LiO2 2. Peroxides- Li2O2, NaO2 3. They are generally soluble in water and stable towards heat. Li2CO3, however is considerably less stable and decomposes readily.
It is used in fire extinguishers.
The p-Block Elements. Chapter 4. Their position is in between s-and p-block elements. Chemistry Important Questions Class 12 are given below.. A block of the periodic table is a set of elements unified by the orbitals their valence electrons or vacancies lie in. The elements constituting the f — block is those elements in which the 4 f and 5 f are progressively in the later of the two long periods.
On moving down the group atomic radius is expected to increase. However, Atomic radius of Ga is less than that of Al. The ionisation enthalpy values do not decrease smoothly down the group. Variation can be explained on the basis of poor screening effect of d and f electrons. Down the group, electro negativity first decreases from B to Al and then increases marginally because of the discrepancies in atomic size of the elements. Density of the elements increases down the group from boron to thallium.
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Enemark R. Minimize formal charge by stealing lone pairs to make additional multiple bond Graphs of reactant and product concentrations change with time as shown below.
A mnemonic is a memory aid used to improve long-term memory and make the process of consolidation easier. Many chemistry aspects, rules, names of compounds, sequences of elements, their reactivity, etc.
d and f block elements class 12 ppt
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The d –block elements are called transition elements and consist of elements lying Catalytic properties:Many transition metals and their compounds show catalytic With K4[Fe(CN)6], CuSO4 gives a reddish brown ppt. of Cu2[Fe(CN)6].
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