Scientific Reasons of Inorganic and Organic Chemistry ,The elements of same group are chemically similar but their physical properties gradually change
... [Show More] down the group.
Group IA elements are called alkali metals while group IIA elements are called alkaline earth metals.
During electrolysis of molten NaCl with molten CaCl2, sodium metal does not mix with calcium metal.
Sodium is stored in kerosene oil.
Na2CO3 gives white ppt. with a solution of MgSO4 in the cold state, while NaHCO3 gives white ppt. with MgSO4 solution on heating only.
s-block elements readily lose their valence electrons.
s-block elements have very low electronegativity.
Hydration energy varies directly to charge and inversely to size of ion. Or Group IIA cations are more strongly hydrated than group IA cations. Or Li+ ions have greater of heat of hydration than Cs+
Hydration energy decreases down each group.
s-block elements require less energy to form M+ and M2+ ions when they are formed in solution.
s-block elements are powerful reducing agent.
Alkaline earths are less powerful reducing agent than alkali metals.
Alkali metals cannot be used in voltaic cells.
Hardness, m.p. and b.p. decrease down each group.
Group IIA elements are more denser than group IA elements.
M.P., B.P. and hardness of alkaline earth metals are higher than alkali metals.
Alkali metals are highly reactive.
Compound of group I and IIA differ in properties.
Carbonates of group IA differ from carbonates of group IIA.
Li and Be differ from other members of their group.
Lithium resembles with Mg (Beryllium resembles with aluminium) in properties.
Electronegativity decreases down the group.
Electronegativity of group IIA is higher than group I A elements.
Electropositivity increases down the group.
Atomic radii of alkali metals are larger than alkaline earth metal.
Ionic radii increase down each group.
Alkaline earths cations are much smaller than alkali metals cations.
Size of cation (Na+) is smaller than parent atom (Na).
Size of anion (Cl¯) is larger than parent atom (Cl).
I.P. decreases down each group.
s-block elements have low 1st I.P.
1st I.P. of alkaline earth metals is higher than corresponding alkali metals.
2nd I.P. is greater than 1st I.P.
Atomic hydrogen is more reactive than molecular hydrogen.
NO2 gas is coloured while its dimer (N2O4) is colourless.
Aluminium metal does not react with nitric acid OR Aluminium metal is less reactive than iron although aluminium is prior to iron in reactivity series.
Aluminium pans should never be cleaned with washing soda. OR Aluminium vessels should never be cleaned with water containing strong alkali.
Solution of H2S turns cloudy when exposed to air.
H2S gas is not dried over caustic potash sticks or passing through concentrated H2SO4.
Borax is used in water softening.
Bromine is displaced from its salt by chlorine but not by iodine.
Aluminium is more metallic than Boron.
Electrolysis of alumina takes place only in the presence of cryolite.
Nitric acid acts as a strong oxidizing agent.
Sulphuric acid acts as a strong oxidizing agent.
Boron is considered as semi-conductor OR Boron generally forms covalent compounds.
Sulphuric acid has higher boiling point and viscosity.
Chlorine water is a bleaching agent.
Diamond is hard while graphite is soft although both are allotropes of carbon.
Diamond is a bad conductor of electricity while graphite is a good conductor of electricity.
Transition metal forms coloured ions and compounds.
Most of the transition metals are paramagnetic but Zn is diamagnetic.
4s orbital is filled prior to 3d orbital but on ionization electrons are first lost from 4s orbital instead of 3d orbital.
Transition elements form complex compounds.
Transition metals and their compounds are used as Catalyst.
Melting and boiling points of transition elements are high.
Copper cooking vessels must be tinned.
NH3 and H2O act as ligands but NH4+ and H3O+ do not.
Silvering of Mirror is based on Redox Reaction.
Transition Elements form interstitial compounds.
Configuration of 24Cr is 3d5 4s1 instead of 3d4 4s2.
Configuration of 29Cu is 3d10 4s1 instead of 3d9 4s2.
The atomic size of sulphur is bigger than oxygen atom.
Hydrogen sulphide is a gas where as water is a liquid.
Water has a high B.P. than hydrogen fluoride although F is more electronegative than O.
Aluminium hydroxide (or zinc hydroxide) is amphoteric.
Graphite is a more stable allotropic form of carbon than diamond.
Li+/Li couple has high negative electrode potential.
Every period starts from ns1 and ends at ns2 np6.
Electron population ratio of aluminium is less than that of boron.
Magnesium is harder than sodium.
Plastic sulphur is elastic in nature.
Ammonia is a stronger base than phosphine
Diamond is lustrous where as carbon is dull.
Water has a high boiling and a high melting point than hydrogen sulphide.
E values for M2+(aq) + 2e- M(s) (where M = Ca, Sr and Ba) are nearly same.
Amines act as bases.
Alcohols are amphoteric OR Alcohols act as weak acid as well as weak base.
Tertiary alcohols cannot undergo dehydrogenation or oxidation.
Primary alcohols on oxidation (or dehydrogenation) give aldehydes while secondary alcohols give ketones.
Alcohols differ from phenols though both of them contain –OH group.
Reaction of primary alcohols with HCl takes place in presence of ZnCl2.
Carbonyl compounds (aldehydes and ketones) act as electrophiles.
Aldehydes are easy to oxidize but ketones are difficult to oxidize OR Ammonical silver nitrate solution (Tollen’s reagent) on Fehling’s solution is reduced by aldehydes but not by ketones or Aldehydes are good reducing agent but ketones are poor reducing agent.
Formaldehyde cannot undergo aldol condensation.
Aldehydes and ketones differ in some reactions though both of them contain carbonyl group.
The double bond in carbonyl group (>C=O) is more reactive than a double bond between carbon and carbon (>C=C<) in alkenes.
Carboxylic acids are weaker acids than mineral (inorganic) acids.
NaCl (or metallic halides) gives white ppt with silver nitrate solution but CCl4 does not.
Carbonium ion can react with nucleophile but carbanion does not.
Alkenes (or propene or oil) can be hydrogenated but not alkanes (or propane or ghee) though both of them are aliphatic hydrocarbons.
Alkenes or alkynes are more reactive than alkanes OR Alkanes are more stable than alkenes or alkynes.
Alkenes (ethene) is more reactive than alkyne (ethyne) although alkene (ethene) contains one and alkyne (ethyne) contains two -bonds.
Benzene behaves as saturated as well as unsaturated compounds. [Show Less]