1. Elements and Compounds Diagonal Relationship and Irregularity
The s-Block Elements
Elements and Compounds
Structure of Atom
Diagonal Relationship and Irregularity
Element
Objectives:
Compounds
Diagonal Relationship of Lithium with Magnesium.
A compound is a substance composed of two or more elements, chemically combined with one another in a fixed proportion.
Anomalous Behaviour of Lithium.
Water, sugar, salt, carbon dioxide, methane etc are the examples of compounds.
Diagonal Relationship of Beryllium with Aluminium.
Anomalous Behaviour of Beryllium.

2. Compounds Non-metals Petroleum Diagonal Relationship of Li with Mg
The s-Block Elements
Non-metals
Mineral Coal and Mineral Oil
Elements and Compounds
Dual Nature of Matter and Radiation
Shapes of s, p and d-orbitals
Diagonal Relationship and Irregularity
Extraction of Sulphur
Petroleum
Element
Diagonal Relationship of Li with Mg
Compounds
A compound is a substance composed of two or more elements, chemically combined with one another in a fixed proportion.
Water, sugar, salt, carbon dioxide, methane etc are the examples of compounds.
Due to small size of lithium, it differs from other alkali metals but resembles with Mg as its size is closer to Mg. Its resemblance with Mg is known as diagonal relationship. Generally the periodic properties show either increasing or decreasing trend along the group and vice versa along the period which brought the diagonally situated elements to closer values.

3. Compounds Structure of Atom Non-metals Petroleum
Mineral Coal and Mineral Oil
The s-Block Elements
Non-metals
Elements and Compounds
Diagonal Relationship and Irregularity
Shapes of s, p and d-orbitals
Petroleum
Dual Nature of Matter and Radiation
Extraction of Sulphur
Element
Diagonal Relationship of Li with Mg
Compounds
Both Li and Mg are harder and have higher melting points.
Due to covalent nature, chlorides of both Li and Mg are deliquescent and soluble in alcohol and pyridine.
A compound is a substance composed of two or more elements, chemically combined with one another in a fixed proportion.
Fluorides, phosphates of Li and Mg are sparingly soluble in water.
Carbonates of Li and Mg decompose on heating and liberate CO2.
Water, sugar, salt, carbon dioxide, methane etc are the examples of compounds.
Li2CO3 → Li2O + CO2  ; Mg CO3 → MgO + CO2   
Hydroxides and nitrates of both Li and Mg decompose on heating to give oxide. Hydroxides of both Li and Mg are weak alkali.
Both Li and Mg combine directly with N2 to give nitrides Li3N and Mg3N2.

4. Compounds Structure of Atom Non-metals Petroleum
Mineral Coal and Mineral Oil
The s-Block Elements
Non-metals
Elements and Compounds
Diagonal Relationship and Irregularity
Shapes of s, p and d-orbitals
Petroleum
Dual Nature of Matter and Radiation
Extraction of Sulphur
Element
Diagonal Relationship of Li with Mg
Compounds
Bicarbonates of Li and Mg are more soluble in water.
A compound is a substance composed of two or more elements, chemically combined with one another in a fixed proportion.
Both Li and Mg combine with carbon on heating.
   2Li + 2C → Li2C2  ; Mg + 2C → MgC2
Li and Mg Form only monoxide on heating in oxygen.
Water, sugar, salt, carbon dioxide, methane etc are the examples of compounds.
    4Li + O2 → 2 Li2O ; 2Mg + O2 → 2 MgO
Li2SO4 like MgSO4 does not form alums.

5. Compounds Structure of Atom Non-metals Petroleum
Mineral Coal and Mineral Oil
The s-Block Elements
Non-metals
Elements and Compounds
Diagonal Relationship and Irregularity
Shapes of s, p and d-orbitals
Petroleum
Dual Nature of Matter and Radiation
Extraction of Sulphur
Element
Anomalous Behaviour of Lithium
Compounds
The small size of the lithium atom and the ion make them behave differently from other elements of the same group.
A compound is a substance composed of two or more elements, chemically combined with one another in a fixed proportion.
Lithium is the hardest of all the alkali metals.
The melting and boiling points of lithium are much higher than those of other elements of group 1.
Lithium is less reactive as compared to other metals and it does not get tarnished readily in air.
Water, sugar, salt, carbon dioxide, methane etc are the examples of compounds.
Lithium is deliquescent and crystallizes as a hydrate, LiCl.2H2O whereas other alkali metal chlorides do not form hydrates.
Lithium bicarbonate is not obtained in the solid form while all other elements of this group form solid bicarbonate.

6. Compounds Structure of Atom Non-metals Petroleum
The s-Block Elements
Mineral Coal and Mineral Oil
Structure of Atom
Non-metals
Elements and Compounds
Dual Nature of Matter and Radiation
Shapes of s, p and d-orbitals
Diagonal Relationship and Irregularity
Petroleum
Extraction of Sulphur
Element
Anomalous Behaviour of Lithium
Compounds
It forms only monoxide, Li2O with oxygen while sodium forms peroxide, Na2O2 and other elements form superoxide, MO2.
A compound is a substance composed of two or more elements, chemically combined with one another in a fixed proportion.
The salts of lithium have lower ionic character than salts of other alkali metals. This is because of high polarizing power of Li+ ion.
Water, sugar, salt, carbon dioxide, methane etc are the examples of compounds.

7. Compounds Non-metals Structure of Atom Petroleum
Mineral Coal and Mineral Oil
The s-Block Elements
Non-metals
Structure of Atom
Elements and Compounds
Dual Nature of Matter and Radiation
Shapes of s, p and d-orbitals
Petroleum
Extraction of Sulphur
Diagonal Relationship and Irregularity
Element
Diagonal Relationship of Be with Al
Compounds
The ionic radius of Be2+ is estimated to be 31 pm : the charge/ radius ratio is nearly the same as that of the Al3+ ion. Hence beryllium resembles aluminium in some ways.
A compound is a substance composed of two or more elements, chemically combined with one another in a fixed proportion.
Like aluminum, beryllium is not readily attacked by acids because of the presence of an oxide film on the surface of the metal.
Water, sugar, salt, carbon dioxide, methane etc are the examples of compounds.
Beryllium hydroxide dissolves in excess of alkali to give a beryllate ion, just as aluminium hydroxide gives aluminate ion.
The chlorides of both beryllium and aluminium have Cl- bridged chloride structure in vapour phase. Both the chlorides are soluble in organic solvents and are strong Lewis acids. They are used as Friedel Craft catalysts.

8. Compounds Non-metals Structure of Atom Petroleum
Mineral Coal and Mineral Oil
The s-Block Elements
Non-metals
Structure of Atom
Elements and Compounds
Dual Nature of Matter and Radiation
Diagonal Relationship and Irregularity
Petroleum
Shapes of s, p and d-orbitals
Extraction of Sulphur
Element
Diagonal Relationship of Be with Al
Compounds
Beryllium and aluminium ions have strong tendency to form complexes.
A compound is a substance composed of two or more elements, chemically combined with one another in a fixed proportion.
Carbides of both the metal reacts with water liberating methane gas.
Be2C + 4H2O → 2Be (OH)2 + CH4 ,  AI4C3 + 12H2O → 4Al (OH)3 + 3CH4 
Water, sugar, salt, carbon dioxide, methane etc are the examples of compounds.
The oxides of both Be and Al i.e. BeO and Al2O3 are high melting insoluble solids.

9. Compounds Non-metals Structure of Atom Petroleum
Mineral Coal and Mineral Oil
The s-Block Elements
Non-metals
Structure of Atom
Elements and Compounds
Dual Nature of Matter and Radiation
Shapes of s, p and d-orbitals
Petroleum
Extraction of Sulphur
Diagonal Relationship and Irregularity
Element
Anomalous Behaviour of Beryllium
Compounds
The properties of beryllium the first member of the alkaline earth metal, differ from the rest of the member. Its is mainly because of its small size, high polarizing power and absence of vacant d – orbitals in its valence shell.
A compound is a substance composed of two or more elements, chemically combined with one another in a fixed proportion.
The melting and boiling points of Be are higher than those other members of Group II.
Beryllium forms covalent compounds whereas other members form ionic compounds.
Water, sugar, salt, carbon dioxide, methane etc are the examples of compounds.
Beryllium carbide reacts with water to give methane whereas carbides of other alkaline earth metals gives acetylene gas.
Beryllium does not exhibit coordination number more than four as it has four orbitals in the valence shell. The other members of this group has coordination number 6.