class 11, chemistry, cbse board, ncert notes, physical chemistry notes, organic Chemistry Notes for Class 11 Download in pdf The s-Block Elements. In the s-block elements the last electron enters in the s-orbital. As the s-orbital can accommodate only two electrons, two groups (1 and 2) belong to the s-block, . s-Block Elements Class 11 Notes to understand group 1 and group 2 To download s block elements class 11 CBSE notes available on BYJU'S click here. and to download s-Block Elements Class 11 Notes PDF register with BYJU's.
|Language:||English, Spanish, Hindi|
|ePub File Size:||18.48 MB|
|PDF File Size:||15.68 MB|
|Distribution:||Free* [*Register to download]|
Free PDF download of Class 11 Chemistry revision notes & short key-notes for Chapter 10 - The s-Block Elements to score high marks in exams, prepared by expert Chemistry teachers from latest edition of CBSE(NCERT) books. Chapter 1 - Some Basic Concepts of Chemistry. The s-Block Elements class 11 Notes Chemistry Chapter 10 in PDF format for free download. Latest chapter wise notes for CBSE exams. Scroll down to download pdf file. Chemistry. CBSE Class 11 Chemistry Notes - The s-Block Elements. Learning the important concepts is very important for every.
The elements in which the last electron enters in the outermost s-orbital are called s-block elements. They include elements of group I and II. They are collectively called alkali metals because they dissolve in water to form strong alkalies. They are collectively called alkaline earth metals except Be because their oxides and hydroxides are found in earth crust and alkaline in nature. The general electronic configuration of s-block elements is [noble gas] ns1 for alkali metals and [noble gas] ns2 for alkaline earth metals.
Li forms only monoxide, sodium forms monoxide and peroxide and other alkali metals form monoxide, peroxide and super oxide. Reaction with water: The alkali metals react with water to liberate hydrogen. Reaction with Hydrogen: Reaction with halogen: Reducing nature: They are strong reducing agents.
Li being the most powerful reducing agent and sodium the least. Due to the smallest atomic radius, Li has the highest hydration enthalpy. So it has high reducing power. Solution in liquid ammonia: The alkali metals dissolve in liquid ammonia to give deep blue solutions which are good conductors. The solution is paramagnetic and on standing slowly liberates hydrogen resulting in the formation of amide MNH2.
The s-block elements. But the other alkali metal chlorides do not form hydrates. LiCl is deliquescent and crystallizes as a hydrate LiCl. Lithium nitrate on heating gives Li2O. Some of these are: Their carbonates decompose easily on heating to form oxides and CO2. Their oxides and hydroxides are much less soluble and their hydroxides decompose on heating. Their chlorides are soluble in ethanol and are deliquescent. Lithium shows some properties different from that of other alkali metals.
Their bicarbonates are stable only in solution. Anomalous Properties of Lithium Due to its small size and high polarizing power. Action of Heat: On heating. Lithium bicarbonate LiHCO3 is stable only in solution. They do not form superoxides. Some important compounds of Sodium 1. Both react slowly with water. CO2 is passed through a concentrated solution of NaCl saturated with ammonia.
It forms only monoxide with oxygen. Li is much harder and has high melting point and boiling point. Diagonal relationship between Li and Mg Li shows the following similarities in properties with Be of the second group. Sodium Carbonate [Na2CO3.
Li is the least reactive but the strongest reducing agent among all the alkali metals. Both Li and Be are harder but lighter than other elements of the respective group. Sodium metal discharged at the cathode combines with mercury to form sodium amalgam.
So calcium gives brick red. Strontium gives crimson red and Barium gives apple green colour to the flame. Hence these elements do not give flame colouration. The Brine solution NaCl solution is electrolysed by using a mercury cathode and a carbon anode. First ionization enthalpies of alkaline earth metals are higher than those of alkali metals. It is prepared commercially by the electrolysis of NaCl in Castner-Kellner cell.
In flame the electrons are excited to higher energy levels and when they return to the ground state. Flame colouration Alkaline earth metals give characteristic colour to the flame. Sodium bicarbonate. It is used in water softening. The electrons in Be and Mg are very strongly bound to the nucleus. It is used in paper. It is used: It is used as a laboratory reagent. These ions participate in the transmission of nerve signals. Cathode reaction: Hydration enthalpy of alkaline earth metal ions decreases with increase in ionic size.
Uses 1. So they do not get excited by the flame. General electronic configuration: Chlorine gas is evolved at the anode.
They activate many enzymes. Be OH 2 dissolves in excess of alkali to give beryllate ion. Beryllium is used in the manufacture of alloys. The chlorides of both the elements have bridged structure in vapour phase. Like alkali metals. Magnesium powder and ribbon is used in flash powders and bulbs. Like Al. Both the chlorides are soluble in organic solvents and are strong Lewis acids.
Diagonal relationship between Beryllium and Aluminium 1. In the vapour phase. The remaining members of the group can have a co-ordination number of 6 by making use of vacant dorbitals. Magnesium carbonate is used in toothpaste. It forms compounds which are highly covalent and get easily hydrolised.
Some of the properties are: A suspension of magnesium hydroxide in water called milk of magnesia is used as antacid in medicine. Reaction with air and water Be and Mg are inert to O2 and H2O because of the formation of oxide film on their surface.
Other elements form monoxide with air. Metallic beryllium is used for making windows of X-ray tubes. Beryllium is not readily attacked by acids because of the presence of an oxide film on the surface of the metal.
They dissolve in liquid ammonia to form deep blue black solution due to the formation of ammoniated electrons.
They are used as Friedel — Crafts catalysts. But the reducing power is less than that of alkali metals. BeCl2 exists as dimer even in vapour phase and is soluble in organic solvents. Uses of Alkali metals 1. Copper-beryllium alloys are used in the preparation of high strength springs.
Magnesium-aluminium alloys are used in air-craft construction. Reaction with acids: It does not show co-ordination number more than 4 as its valence shell contains only 4 orbitals. The oxide and hydroxide of Be are amphoteric in nature.
Be has high ionization enthalpy and small size. The product obtained is called slaked lime. CaCO3 [Lime stone] Calcium carbonate occurs in nature in several forms like limestone. On passing CO2 continuously. Calcium Carbonate. This process is called slaking of lime. Calcium is used in the extraction of metals from oxides which are difficult to reduce with carbon. So it is used as a flux in metallurgy. Calcium Oxide. It is used in the purification of sugar and in the manufacture of dye stuffs.
Calcium and barium metals are used to remove air from vacuum tubes. The compounds of alkali metals are predominantly ionic. Their oxides and hydroxides are soluble in water forming strong alkalies. Important compounds of sodium include sodium carbonate, sodium chloride, sodium hydroxide and sodium hydrogen carbonate. Sodium hydroxide is manufactured by using Castner-Kellner process and sodium carbonate by Solvay process.
Biological importance of sodium and potassium Sodium ions help to regulate flow of water across the cell membranes, transportation of sugars and amino acids inside the cells.
Potassium ions activate many enzymes, takes part in oxidation of glucose. Potassium ions together with sodium ions are responsible for transmission of nerve signals and maintenance of ionic gradient across the cell.
Group 2 elements: Alkaline earth metals The chemistry of alkaline earth metals is very much like that of the alkali metals. However, some differences arise because of reduced atomic and ionic sizes and increased cationic charges in case of alkaline earth metals.
Their oxides and hydroxides are less basic than the alkali metal oxides and hydroxides. It increases down the group. Ionization enthalpy: value decreases down the group. Hydration enthalpy: decreases as the size of the metal ion increases down the group. Chemical features of alkali metals: Reducing character: Alkaline earth metals are weak reducing agents.
Reaction with oxygen: Form oxides MO on heating with excess of oxygen with exception of Ba and Ra which form peroxides MO2 Reaction with halogen: combine directly with halogen to form corresponding halides. Reaction with water: Elements of this group are less reactive with water because they are less electropositive in nature.
Reaction with hydrogen: The members of this group except Be combine with hydrogen directly upon heating to form metal hydrides. Uses of some important compounds: Industrially important compounds of calcium include calcium oxide lime , calcium hydroxide slaked lime , calcium sulphate Plaster of Paris , calcium carbonate limestone and cement. Portland cement is an important constructional material. It is manufactured by heating a pulverised mixture of limestone and clay in a rotary kiln.
All these substances find variety of uses in different areas. Caustic soda is used in soap, textile and petroleum industry.
Sodium carbonate is used in soap and glass industry, in making paints and dye, in metal refining process. Quick lime is used in the preparation of cement, glass and calcium carbide.