20Periodic table

📚
DEFINITION
▢ Periodic Table: Arrangement of all known elements according to properties so similar elements fall in same vertical columns and dissimilar elements are separated.
▢ Father of Periodic Table: Mendeleev
📚
HISTORY OF PERIODIC TABLE
▢ Prout's Unitary Hypothesis: Atomic weights of elements are simple multiples of atomic weight of hydrogen.
▢ Dobereiner:
  • •
    First attempt to correlate chemical properties with atomic weight.
  • •
    Dobereiner's triads: Li-Na-K, Ca-Sr-Ba, Cl-Br-I, P-As-Sb.
  • •
    Fe-Co-Ni triad not applicable.
▢ Newland's Octave Theory:
  • •
    Given by Newland.
  • •
    Based on musical tone.
  • •
    Similar properties repeat at every 8th element when arranged in increasing atomic weight.
  • •
    Called law of octaves. [BPKIHS 2003]
▢ Lothar Meyer's Curve:
  • •
    Curve plotted between atomic weight and atomic volume.
  • •
    Similar elements occupy similar positions on the curve.
  • •
    Alkali metals occupy peaks of the curve.
▢ Mendeleev's Periodic Law:
  • •
    Physical and chemical properties of elements are periodic function of atomic weight.
  • •
    Elements arranged in increasing atomic weights.
  • •
    Original table: 8 vertical groups I-VIII and 7 horizontal periods.
  • •
    Modified Mendeleev table: 9 groups = I-VII + VIII + zero group of noble gases.
▢ Defects of Mendeleev's Table:
  • •
    Position of hydrogen not fixed.
  • •
    Position of isotopes not fixed.
  • •
    Position of lanthanides and actinides not fixed.
  • •
    Dissimilar elements placed in same group, e.g. alkali metals and coinage metals: Cu, Ag, Au.
▢ Anomalous Pair of Elements:

Table 1: Higher atomic weight before lower atomic weight

Anomalous pair
Order
Argon / Potassium
Ar \((39.9)\) before K \((39.1)\)
Cobalt / Nickel
Co \((58.94)\) before Ni \((58.69)\)
Tellurium / Iodine
Te \((127.5)\) before I \((126.9)\)
Mendeleev's predicted elements
  • •
    Eka-boron = Scandium
  • •
    Eka-silicon = Germanium
  • •
    Eka-aluminium = Gallium
  • •
    Eka-manganese = Technetium
📚
MODERN PERIODIC TABLE
▢ Given By: Moseley.
▢ Modern Periodic Law: Physical and chemical properties of elements are periodic functions of their atomic numbers.
▢ Structure:
  • •
    7 horizontal series = periods.
  • •
    18 vertical columns = groups.
  • •
    Elements arranged in increasing atomic number.
  • •
    Elements at intervals of 2, 8, 8, 18, 18, 32, 32 show similar properties and belong to particular group.
  • •
    Special numbers 2, 8, 18, 32 are called magic numbers.
▢ Main Features:

Table 1: Periods

Period
Elements
Type / note
1st
2 elements: H-He
Shortest period
2nd
8 elements: Li-Ne
Short period
3rd
8 elements: Na-Ar
Short period
4th
18 elements: K-Kr
Long period
5th
18 elements: Rb-Xe
Long period
6th
32 elements: Cs-Rn
Longest period
7th
Incomplete
Synthetic / radioactive elements common
▢ Transuranium Elements: Elements from atomic number 93 onwards; purely synthetic and radioactive.
▢ Groups:
  • •
    16 vertical columns in old notation: IA to VIIB, VIII and 0.
  • •
    Subgroups IA, IIA, IIIA to VIIA: all inner shells complete; only outermost shell incomplete; called normal elements.
  • •
    Subgroups IB, IIB, IIIB to VIIB and VIII: outermost and penultimate shells incomplete; called transition elements.
  • •
    Group 0 / 18: no incomplete shell; low reactivity; inert gases / noble gases.
  • •
    14 elements after lanthanum = lanthanides.
  • •
    14 elements after actinium = actinides.
  • •
    Lanthanides and actinides placed in separate bottom rows for convenience.
📚
S-BLOCK ELEMENTS
▢ Members: Group IA alkali metals and Group IIA alkaline earth metals.
▢ Electronic Configuration:
  • •
    Alkali metals: \(ns^1\)
  • •
    Alkaline earth metals: \(ns^2\)
▢ Properties:
  • •
    Largest atomic radii in corresponding periods.
  • •
    Lowest ionization energy.
  • •
    Most electropositive.
  • •
    Soft and malleable.
  • •
    Hydroxides are strong bases.
  • •
    Most s-block elements impart colour to flame.
Exception
Be and Mg do not impart flame colour due to small size and high ionization potential.
▢ Position: Situated on left side of periodic table.
📚
P-BLOCK ELEMENTS
▢ Definition: Elements in which p-orbitals are progressively filled; last electron enters p-orbital.
▢ Groups: IIIA/13 to zero/18 group.
▢ General Configuration: \(ns^2np^{1-6}\)
▢ Outer Configurations:
  • •
    \(ns^2np^1\)
  • •
    \(ns^2np^2\)
  • •
    \(ns^2np^3\)
  • •
    \(ns^2np^4\)
  • •
    \(ns^2np^5\)
  • •
    \(ns^2np^6\)
▢ Inert Gases: Elements having \(ns^2np^6\) are grouped separately as inert gases / aerogens.
▢ Families:

Table 1: p-block families

Group
Family
IIIA / 13
Boron family
IVA / 14
Carbon family
VA / 15
Nitrogen family / Pnicogens
VIA / 16
Oxygen family / Chalcogen family / Ore-forming family
VIIA / 17
Halogen family / Salt-forming family
Helium
He has no p-orbital but is placed in p-block.
Representative elements
s-block and p-block elements are called normal or representative elements.
Typical elements
Elements of 3rd period are called typical elements: Na, Mg, Al, Si, P, S, Cl.
📚
D-BLOCK ELEMENTS
▢ Definition: Elements in which last electron enters d-orbital; d-orbitals are progressively filled.
▢ Groups: IIIB/3, IVB/4, VB/5, VIB/6, VIIB/7, VIII/8-10, IB/11, IIB/12.
▢ General Configuration: \((n-1)d^{1-10}ns^{0-2}\)
▢ Important Points:
  • •
    Pd \((Z=46)\): \([Kr]4d^{10}5s^0\); only d-block element with zero s-electron.
  • •
    d-block elements show variable oxidation states.
  • •
    Most d-block elements form coloured salts.
  • •
    Compounds are generally paramagnetic.
  • •
    More electropositive than p-block and less electropositive than s-block elements.
  • •
    Transition metals have highest density compared with s-block and p-block.
  • •
    Technetium \((Tc)\) = first synthetic transition metal.
▢ Series:

Table 1: Transition series

Series
Elements
Period
No. of elements
1st transition series / 3d-series
Sc \((21)\) to Zn \((30)\)
4th
10
2nd transition series / 4d-series
Y \((39)\) to Cd \((48)\)
5th
10
3rd transition series / 5d-series
La \((57)\), Hf \((72)\) to Hg \((80)\)
6th
10
4th transition series / 6d-series
Ac \((89)\), Rf \((104)\) onwards
7th
Incomplete
▢ Special Points:
  • •
    d-block metals show horizontal and vertical similarities.
  • •
    IB group = coinage metals: Cu, Ag, Au.
  • •
    IIB group = volatile metals: Zn, Cd, Hg.
  • •
    W / tungsten has highest melting point and boiling point among all elements.
  • •
    Zn, Cd, Hg are not considered transition metals because of completely filled d-orbital and their salts are colourless and diamagnetic.
  • •
    Zn, Cd, Hg are placed in d-block due to presence of d-orbital.
📚
F-BLOCK ELEMENTS
▢ Also Called: Inner transition elements.
▢ Definition: Elements in which last electron is added to f-orbital; f-orbitals are progressively filled.
▢ Shell Involved: f-orbital lies inner to penultimate shell.
▢ General Configuration: \((n-2)f^{1-14}(n-1)d^{0-10}ns^2\)
▢ Lanthanide Contraction: Due to increase in effective nuclear charge.
▢ Exceptional Electronic Configuration:
  • •
    Not according to Aufbau principle.
  • •
    3d series exceptions: Cr \((24)\), Cu \((29)\).
▢ 4d Series:

Table 1: 4d series elements

Y
Zr
Nb
Mo
Tc
Ru
Rh
Pd
Ag
Cd
Yttrium
Zirconium
Niobium
Molybdenum
Technetium
Ruthenium
Rhodium
Palladium
Silver
Cadmium
39
40
41
42
43
44
45
46
47
48
▢ Aufbau Exceptions in 4d: Nb, Mo, Ru, Rh, Pd, Ag do not obey Aufbau principle.
📚
PSEUDO INERT GAS CONFIGURATION
▢ Meaning: 18-electron configuration with covalent bond character.
▢ Given By: IB group elements: Cu, Ag, Au in +1 oxidation state.

Table 1: Pseudo inert gas examples

Group
Elements / oxidation state
Nature
IB
Cu, Ag, Au in +1 O.S.
CuCl covalent
IIB
Zn, Cd, Hg in +2 O.S.
ZnCl2 and HgCl2 covalent
IIIA
Ga, In, Tl in +3 O.S.
IVA
Ge, Sn, Pb in +4 O.S.
▢ Distribution:
  • •
    Nearly 75% periodic table is covered by metals.
  • •
    p-block contains metals, non-metals and metalloids.
▢ Metalloids:
  • •
    Al, Ga, Ge, Sb, As
  • •
    Ga is liquid at room temperature.
  • •
    As is sublimate metalloid.
📚
SPECIAL POINTS
▢ Elemental State:
  • •
    Radioactive inert gas = Radon \((Rn)\).
  • •
    B, C, Si, P, S are solids.
  • •
    Phosphorus: tetra-atomic \((P_4)\).
  • •
    Sulphur: octa-atomic \((S_8)\).
  • •
    Elementary gases \(N_2, O_2, Cl_2, F_2\) are diatomic; explained by Avogadro's hypothesis.
  • •
    Inert gases are monoatomic; explained by Molecular Orbital Theory or \(C_p/C_v=1.66\).
▢ Important Elements:
  • •
    Liquid non-metal = \(Br_2\).
  • •
    \(I_2\) sublimes: solid state black, vapour state violet.
  • •
    Highest density metal = Osmium \((Os)\).
  • •
    Highest melting point metal = Tungsten \((W)\).
  • •
    Lowest melting point metal = Mercury \((Hg)\).
  • •
    Only liquid metal = Mercury \((Hg)\).
  • •
    Cs and Fr are low melting point metals.
  • •
    Highest melting point non-metal = Carbon.
▢ Hydrogen:
  • •
    Hydrogen is electropositive as well as electronegative.
  • •
    Position of hydrogen is not clearly indicated.
  • •
    Placed in 1st group with alkali metals and in 7th group with halogens.
▢ Extremes:
  • •
    Highest electronegative element = Fluorine.
  • •
    Most electropositive element = Cesium.
  • •
    Highest electron affinity element = Chlorine.
📚
PERIODIC PROPERTIES: VALENCY
▢ Definition: Combining capacity of element; determined by number of H atoms or double the number of O atoms combining with element.
▢ Group Trend:
  • •
    In a group, valency is constant.
  • •
    Group number / outermost shell electrons determine valency.
  • •
    Alkali metals: 1
  • •
    Alkaline earth metals: 2
  • •
    Al: 3
  • •
    Most elements show valency 2, 3 or 4; variable valency common.
  • •
    Only Os and Ru show valency 8.
▢ VIII Group:

Table 1: Common valencies in VIII group

Element
Valency
Fe
2, 3
Co
2, 3
Ni
2
Pd
2, 4
Pt
2, 4
▢ Period Trend with Hydrogen:
  • •
    First valency increases then decreases.
  • •
    \(NaH, MgH_2, AlH_3, SiH_4, PH_3, H_2S, HCl\)
  • •
    Valency order: 1, 2, 3, 4, 3, 2, 1.
  • •
    Hydride character changes from ionic/saline to covalent.
▢ Period Trend with Oxygen:
  • •
    Valency increases from left to right.
  • •
    \(Na_2O, MgO, Al_2O_3, SiO_2, P_2O_5, SO_3, Cl_2O_7\)
  • •
    Valency order: 1, 2, 3, 4, 5, 6, 7.
📚
PERIODIC PROPERTIES: ATOMIC RADII
▢ Definition: Distance from nucleus to outermost shell.
▢ Types:
  • •
    Covalent radius
  • •
    Metallic radius
  • •
    Van der Waal radius
▢ Covalent Radius:
    ◉ **type: bullet
  1. Used for single covalent bond.
  2. Half of bond length.
  3. \(r*{covalent}=\dfrac{C-C}{2}\)
▢ Bond Length:

Table 1: Carbon-carbon bond length

Bond
Bond length
C-C
\(1.54\,A^\circ\)
C=C
\(1.33\,A^\circ\)
C≡C
\(1.20\,A^\circ\)
▢ Metallic Radius: Present in metal in bonded form.
▢ Van der Waal Radius: Present in inert gases / non-bonded atoms.
▢ Relations:
  • •
    Van der Waal radius > metallic radius > covalent radius.
  • •
    Covalent bond > metallic bond in strength.
▢ Trends:
  • •
    Down a group: atomic radius increases due to increase in principal quantum number / orbit.
  • •
    Across a period: atomic radius decreases due to increase in nuclear charge.
  • •
    Same period inert gas has highest atomic radius due to Van der Waal radius.
📚
PERIODIC PROPERTIES: IONIC RADII
▢ Definition: Radius of ion in bonded form.
▢ Trends:
  • •
    Down a group: ionic radius increases.
  • •
    Across a period: ionic radius decreases.
  • •
    Greater positive charge of cation → smaller size → more covalent character.
  • •
    Greater negative charge of anion → larger size → more covalent character.
▢ Isoelectronic Ions:
  • •
    Radii of isoelectronic ions determined by \(\dfrac{Z}{e}\) ratio.
  • •
    Smaller \(\dfrac{Z}{e}\) ratio → larger size.
  • •
    \(Z=\) atomic number.
  • •
    \(e=\) number of electrons.
▢ Cation and Anion:
  • •
    Cation is smaller than parent atom.
  • •
    Anion is larger than parent atom.
  • •
    \(Na>Na^+\)
  • •
    \(F^->F\)
▢ Isoelectronic Cations:
  • •
    \(Li^+>Be^{2+}>B^{3+}>C^{4+}\) in ionic radius.
  • •
    Covalent character increases: \(LiCl
  • •
    \(CCl_4\) is most covalent.
▢ Isoelectronic Anions:
  • •
    \(C^{4-}>N^{3-}>O^{2-}>F^-\) in size.
  • •
    Covalent character: \(CH_4>NH_3>H_2O>HF\).
▢ Example:
❖ Question: Which is largest among \(Na^+\), \(Mg^{2+}\), \(O^{2-}\), \(F^-\)?
❖ Answer: \(O^{2-}\) is largest because it has smaller \(Z/e\) ratio.
📚
PERIODIC PROPERTIES: IONIZATION ENERGY
▢ Definition: Energy required to remove most loosely bound electron from isolated gaseous atom to form cation.
▢ Nature: Endothermic process.
▢ Unit: Electron volt \((eV)\) or \(kJ\,mol^{-1}\).
▢ Trends:
  • •
    Down a group: ionization energy decreases.
  • •
    Across a period: ionization energy increases.
▢ Factors:
  • •
    Size of atom
  • •
    Penetration effect / shape of orbital
  • •
    Stable configuration
  • •
    Shielding / screening effect
  • •
    Successive ionization energy
▢ Size Effect:
  • •
    \(I.E. \propto \dfrac{1}{size}\)
  • •
    Lower I.E. → more electropositive nature.
  • •
    Lower I.E. → stronger reducing agent.
  • •
    Lower I.E. → stronger basic nature of oxides and hydroxides.
  • •
    Cs has lowest I.E.; most electropositive.
  • •
    Cs shows photoelectric effect due to lowest I.E.
  • •
    CsOH is strongest base.
  • •
    In aqueous solution, Li is most powerful reducing agent due to electrode potential.
  • •
    In gaseous state, Cs is most powerful reducing agent.
▢ Penetration Effect:
  • •
    More penetrating orbital → electron held more tightly by nucleus → higher I.E.
  • •
    Penetration order: \(ns>np>nd>nf\).
▢ Stable Configuration:
  • •
    Half-filled and completely filled orbitals are more stable.
  • •
    Stability: \(p^6>d^{10}>p^3>d^5\).
  • •
    As stability increases, I.E. increases.
  • •
    Inert gases have highest I.E. due to complete orbital.
  • •
    He has highest I.E. due to small size.
  • •
    \(I.E.*{Be}>I.E.*B\) because Be has \(2s^2\), B has \(2s^22p^1\).
  • •
    \(I.E.*{Mg}>I.E._{Al}\) due to completely filled s-orbital of Mg.
  • •
    \(I.E._N>I.E._O\) because N has half-filled \(2p^3\) configuration.
▢ Shielding Effect:
  • •
    Used for multi-electron orbit.
  • •
    Inner electrons act as screen between nucleus and outer electron.
  • •
    Greater shielding effect → lower I.E.
  • •
    Screening effect decreases as \(s>p>d>f\).
▢ Successive Ionization Energy:
  • •
    \(I.E._1
  • •
    \(I.E._1\) of Be > \(I.E.*1\) of B.
  • •
    \(I.E.*2\) of Be < \(I.E.*2\) of B.
📚
PERIODIC PROPERTIES: ELECTRON AFFINITY
▢ Definition: Energy released when an extra electron is added to isolated gaseous atom to form anion.
▢ Nature: Exothermic process.
▢ Trends:
  • •
    Down a group: electron affinity decreases.
  • •
    Across a period: electron affinity increases.
  • •
    \(E.A. \propto \dfrac{1}{size\ of\ atom}\)
▢ Important Points:
  • •
    Inert gases have almost zero E.A. due to completely filled orbital.
  • •
    Alkaline earth metals have almost zero E.A. due to completely filled s-orbital.
  • •
    Nitrogen has very low E.A. due to half-filled orbital.
  • •
    Halogens have highest E.A.
  • •
    Chlorine has highest E.A. in periodic table.
  • •
    E.A. is related to bond dissociation energy.
  • •
    Fluorine has slightly lower E.A. than chlorine due to very small atomic size.
▢ Exceptions:
  • •
    \(E.A.*{F_2}
  • •
    \(E.A.*{O_2}
  • •
    \(E.A.*{N_2}
▢ Halogen Order: \(Cl_2>F_2>Br_2>I_2\)
▢ Oxidising Property: Greater E.A. → stronger oxidising property.
▢ Order: \(E.A.: O>C>B>N\)
📚
INERT PAIR EFFECT
▢ Shown By: p-block metals of B-family, C-family and N-family.
▢ Definition: Lower oxidation state is more stable than higher oxidation state due to \(ns^2\) configuration in which s-orbital is completely filled and less involved in bond formation.
▢ Trend: Stability of lower oxidation state increases down the group.

Table 1: Lower vs higher oxidation state compounds

Oxidation state
Nature
Lower oxidation state
Ionic, Lewis base, reducing agent
Higher oxidation state
Covalent, Lewis acid, oxidising agent
📚
FAJAN'S RULE
▢ Meaning: Covalent character in ionic compound depends on polarizing power and polarizability.
▢ Cation Effect:
  • •
    Smaller cation → greater polarizing power → greater covalent character.
  • •
    Down the group, polarizing power decreases.
  • •
    Example: \(LiCl\) is more covalent than chlorides of Na, K, Rb, Cs.
▢ Anion Effect:
  • •
    Larger anion → greater polarizability → greater covalent character.
  • •
    Covalent character increases: \(CaF_2
  • •
    \(CaF_2\) is more ionic; \(CaI_2\) is more covalent.
▢ Charge Effect:
  • •
    Greater positive charge of cation → greater polarizing power → greater covalent character.
  • •
    Polarizing power increases: \(Li^+
  • •
    Covalent character increases: \(LiCl
  • •
    Greater negative charge of anion → greater polarizability → greater covalent character.
  • •
    Polarizability decreases: \(C^{4-}>N^{3-}>O^{2-}>F^-\).
  • •
    Covalent character decreases: \(CH_4>NH_3>H_2O>HF\).
📚
DIAGONAL RELATIONSHIP
▢ Also Called: Bridge element relationship.
▢ Definition: Elements of 2nd period are bridge elements; their properties resemble diagonal elements of 3rd period.
▢ Pairs:

Table 1: Diagonal pairs

2nd period
3rd period
Li
Mg
Be
Al
B
Si
▢ Causes:
  • •
    Almost same atomic size.
  • •
    Almost same electronegativity; main cause.
  • •
    High ionic potential / polarizing power.
Bridge element
Sometimes Mg alone is considered as bridge element.
📚
CHEMICAL SIMILARITIES BETWEEN LI AND MG
▢ Similarities:
  • •
    Li is hard metal like Mg; unlike other alkali metals.
  • •
    Li reacts slowly with water like Mg; other alkali metals react vigorously.
  • •
    LiH and \(MgH_2\) are covalent; other alkali metal hydrides are ionic.
  • •
    Li reacts directly with carbon to form carbide similar to Mg.
  • •
    Other alkali metals have no direct reaction with carbon.
  • •
    Li reacts with \(N_2\) similar to Mg; other alkali metals have no direct reaction with \(N_2\).
  • •
    LiCl is deliquescent like \(MgCl_2\) due to hydrated salt formation.
  • •
    LiCl is covalent like \(MgCl_2\); other alkali metal chlorides are ionic.
  • •
    LiCl is Lewis acid / acidic salt like \(MgCl_2\); other alkali metal chlorides are neutral salts.
  • •
    \(Li_2CO_3\) is water insoluble like \(MgCO_3\); other alkali metal carbonates are water soluble.
  • •
    \(Li_2CO_3\) decomposes on heating like \(MgCO_3\); other alkali metal carbonates are heat stable.
  • •
    Li forms monoxide similar to Mg; other alkali metals form monoxide, peroxide and superoxide.
  • •
    LiOH is weak base similar to \(Mg(OH)_2\).
  • •
    \(LiNO_3\) decomposes on heating with reddish brown \(NO_2\) vapour and \(O_2\), similar to Mg nitrate.
  • •
    LiF, \(Li_3PO_4\), \(Li_2S\) are water insoluble like \(MgF_2\), \(Mg_3(PO_4)_2\), MgS.
▢ Carbide Reactions:
  • •
    \(Li+C\xrightarrow{\Delta}Li_2C_2\xrightarrow{H_2O}CH\equiv CH+LiOH\)
  • •
    \(Mg+C\xrightarrow{\Delta}MgC_2\xrightarrow{H_2O}CH\equiv CH+Mg(OH)_2\)
▢ Nitride Reactions:
  • •
    \(Li+N_2\rightarrow Li_3N\)
  • •
    \(Mg+N_2\rightarrow Mg_3N_2\)
  • •
    Hydrolysis gives \(NH_3\).
▢ Hydrated Chlorides:
  • •
    \(LiCl\cdot2H_2O\)
  • •
    \(MgCl_2\cdot6H_2O\)
  • •
    \(MgCl_2\cdot8H_2O\)
▢ Carbonate Solubility: \(Li_2CO_3
▢ Nitrate Heating:
  • •
    \(LiNO_3\xrightarrow{\Delta}Li_2O+NO_2+O_2\)
  • •
    \(Mg(NO_3)_2\xrightarrow{\Delta}MgO+NO_2+O_2\)
  • •
    \(NaNO_3\xrightarrow{\Delta}NaNO_2+O_2\)
  • •
    Most metallic nitrates on heating give metallic oxide, \(NO_2\) and \(O_2\).
  • •
    \(AgNO_3\), \(Hg_2(NO_3)_2\), \(Hg(NO_3)_2\) on heating give metal.
📚
CHEMICAL SIMILARITIES BETWEEN BE AND AL
▢ Similarities:
  • •
    Both Be and Al are amphoteric metals.
  • •
    Both react with acid and alkali to liberate \(H_2\).
  • •
    Other alkaline earth metals do not react with alkali.
  • •
    BeO and \(Be(OH)_2\) are amphoteric like \(Al_2O_3\) and \(Al(OH)_3\).
  • •
    BeCl2 is Lewis acid similar to \(AlCl_3\).
  • •
    BeCl2 is covalent similar to \(AlCl_3\).
  • •
    Other alkaline earth metal chlorides are neutral salts.
▢ Reactions:
  • •
    \(Be+2HCl\rightarrow BeCl_2+H_2\)
  • •
    \(Be+2NaOH\rightarrow Na_2BeO_2+H_2\)
  • •
    \(2Al+6HCl\rightarrow2AlCl_3+3H_2\)
  • •
    \(2Al+6NaOH\rightarrow2Na_3AlO_3+3H_2\)
  • •
    \(2Al+2NaOH+2H_2O\rightarrow2NaAlO_2+3H_2\)
▢ Basic Strength: \(Be(OH)_2
▢ Important Oxides and Hydroxides:

Table 1: Common names

Formula
Common name / use
BeO
Beryllia
\(Al_2O_3\)
Alumina / Corundum
MgO
Magnesia
\(Mg(OH)_2\)
Milk of magnesia; used as antacid
CaO
Quick lime
\(Ca(OH)_2\)
Milk of lime / slaked lime / lime water
SrO
Strontia
BaO
Baryta
\(Ba(OH)_2\)
Baryta solution / baryta water
▢ Sulphate Solubility:
  • •
    BeSO4 soluble like \(Al_2(SO_4)_3\).
  • •
    MgSO4 soluble.
  • •
    CaSO4 sparingly soluble.
  • •
    SrSO4 and BaSO4 insoluble.
  • •
    BaSO4 is opaque to X-ray and used in diagnosis of stomach ulcer as barium meal.
▢ Carbides:
  • •
    \(Be_2C+H_2O\rightarrow CH_4+Be(OH)_2\)
  • •
    \(Al_4C_3+H_2O\rightarrow CH_4+Al(OH)_3\)
  • •
    Other alkaline earth metal carbides hydrolyse to form \(C_2H_2\).
📚
SIMILARITIES BETWEEN B AND SI
▢ Similarities:
  • •
    Both are non-metals.
  • •
    Both react with alkali to liberate \(H_2\).
  • •
    \(B_2O_3\) is acidic oxide similar to \(SiO_2\).
  • •
    \(BX_3\) is Lewis acid similar to \(SiX_4\).
  • •
    \(B_4C\) and SiC are hardest artificial known substances.
  • •
    \(B_4C\) = Norbide.
  • •
    \(SiC\) = Carborundum.
  • •
    \(B_4C\) and SiC are not hydrolysed.
▢ Reactions:
  • •
    \(B+NaOH\rightarrow NaBO_2+H_2\)
  • •
    \(Si+NaOH\rightarrow Na_2SiO_3+H_2\)
  • •
    \(Na_2SiO_3\) = sodium silicate / water glass
▢ Oxide Nature:

Table 1: Oxide nature in group 13

Oxide
Nature
\(B_2O_3\)
Acidic
\(Al_2O_3, Ga_2O_3\)
Amphoteric
\(In_2O_3, Tl_2O_3\)
Basic
▢ Lewis Acid Strength:
  • •
    \(BX_3>AlX_3>GaX_3>InX_3>TlX_3\); Lewis acid strength decreases.
  • •
    \(BI_3>BBr_3>BCl_3>BF_3\); decreasing Lewis acid order.
📚
PERIODIC PROPERTIES: ELECTRONEGATIVITY
▢ Definition: Tendency of an atom in a compound to attract shared pair of electrons towards itself.
▢ Trends:
  • •
    Down a group: electronegativity decreases.
  • •
    Across a period: electronegativity increases.
  • •
    \(E.N.\propto\dfrac{1}{size\ of\ atom}\).
  • •
    Greater number of valence electrons → greater E.N.
  • •
    Greater positive charge of ion → greater E.N.; \(Fe
  • •
    Greater s-character → greater E.N.; \(sp>sp^2>sp^3\).
▢ Scales:
  • •
    Pauling scale
  • •
    Mulliken scale
  • •
    Sorenson scale
▢ Bond Angle Relation:
  • •
    Greater E.N. of central atom → greater bond angle.
  • •
    \(H_2O>H_2S>H_2Se>H_2Te\).
  • •
    \(NH_3>PH_3>AsH_3>SbH_3>BiH_3\).
  • •
    If central atom is same, lower E.N. of attached atom → greater bond angle.
  • •
    \(PCl_3
📚
READ AND DIGEST
▢ Important Points:
  • •
    Neutron/proton ratio does not reflect periodicity of elements.
  • •
    Proton has very large hydration energy.
  • •
    Variable valency is due to inert pair effect.
  • •
    \(F_2\) has lower E.A. than \(Cl_2\) due to small radius and high electron density.
  • •
    Across a period, atomic number increases and atomic size decreases.
  • •
    In isoelectronic ions \(C^{4-},N^{3-},O^{2-},F^-,Na^+,Mg^{2+},Al^{3+},Si^{4+}\), size decreases as nuclear charge increases.
  • •
    Highest ionization potential is shown by inert gases in respective periods.
  • •
    Down a group electron affinity decreases; across a period electron affinity increases.
  • •
    Halogens have highest electronegativity in respective periods.
  • •
    Electronegativity of inert gases is zero.
  • •
    Electronegativity increases with increase in positive charge on cation: \(Mn^{2+}
  • •
    Electronegativity decreases with increase in negative charge: \(X^+>X>X^-\).
  • •
    Hannay-Smith relation: percentage ionic character \(=16(X_A-X_B)+3.5(X_A-X_B)^2\).
  • •
    First period unlike other periods does not start with alkali metal but ends with noble gas.
  • •
    Cation is always smaller than parent atom; anion is always larger than parent atom.
  • •
    In transition elements, atomic and ionic radii first decrease until d-subshell is nearly half-filled, then remain almost same due to shielding of inner d-electrons.
  • •
    Fe, Co, Ni and Cu have nearly same atomic radius due to shielding effect of \((n-1)d\) subshell.
  • •
    Size order of iodine species: \(I^->I>I^+\).
  • •
    Ionization energy of Al is smaller than Mg because IE in Al involves removal of p-electron, which is easier.
  • •
    Addition of 2nd electron to neutral atom is always endothermic.
  • •
    Electronegativity has no unit.
  • •
    Rare gases = inert gases.
  • •
    Rare earth metals = lanthanides = 14 elements.
  • •
    Iridium is heaviest metal.
  • •
    Ionic potential is also called polarizing power.
  • •
    K, Fe and Zn are trace elements of period 4 required in very small quantity for health.
▢ Ionization Enthalpy Orders:
  • •
    3rd period first I.E.: \(Na
  • •
    3rd period second I.E.: \(Mg
  • •
    2nd period first I.E.: \(Li
  • •
    2nd period second I.E.: \(Be
  • •
    First I.P. of Na, Mg, Al, Si: \(Na
  • •
    Second I.P. = energy required to remove one mole electrons from one mole gaseous cations.
▢ Radii and Electronegativity Orders:
  • •
    Increasing radii example: \(Be^{2+}
  • •
    Electronegativity increases in order \(P
  • •
    Second ionization potential of C, N, O, F: \(O>F>N>C\).
📚
PERIODIC PROPERTY TRENDS

Table 1: Trends in group and period

Property
Group: top to bottom
Period: left to right
Atomic radius
Increases
Decreases
Ionization energy
Decreases
Increases
Electron affinity
Decreases
Increases
Electronegativity
Decreases
Increases
Electropositive / metallic character
Increases
Decreases
Oxidising power
Decreases
Increases
Reducing power
Increases
Decreases
📚
SOME IMPORTANT RELATIONS
▢ Relations:
  • •
    \(Atomic\ radius\propto\dfrac{1}{Ionization\ potential}\)
  • •
    \(Atomic\ radius\propto\dfrac{1}{Electronegativity}\)
  • •
    \(Ionization\ potential\propto Electronegativity\)
  • •
    \(Metallic\ character\propto\dfrac{1}{Electronegativity}\)
  • •
    \(Metallic\ character\propto\dfrac{1}{Ionization\ potential}\)
  • •
    \(Non\text{-}metallic\ character\propto Electronegativity\)
  • •
    \(Electron\ affinity\propto\dfrac{1}{Screening\ effect}\)
  • •
    \(Effective\ nuclear\ charge\propto\dfrac{1}{Atomic\ radius}\)
Q1.
Which one of the following has highest electronegativity?
📅I.E.
Q2.
The element Uranium (At. No. 92) belongs to
📅I.E. 2003
Q3.
Atomic radius is nearly equal in
📅I.E. 2006
Q4.
Lithium shows diagonal relationship with Magnesium because
📅BPKIHS 2006
Q5.
The correct sequence of ionization energies is
📅BPKIHS 2011
Q6.
Correct order of increasing ionization energy is
📅I.E. 2006
Q7.
Which of the following elements has the lowest ionization energy?
📅I.E.
Q8.
Which of the following is correct order of electron affinity?
📅I.E.
Q9.
Alkali metal in each period has
📅IOE
Q10.
Chemical and physical properties of an element are the function of their
📅IOE
Q11.
According to Mendeleev, properties of elements are periodic function of their
📅IOE
Q12.
Variable valency is generally shown by
📅IOE
Q13.
Iron belongs to which block of periodic table?
📅IOE
Q14.
Beryllium shows diagonal relationship with
📅IOE
Q15.
The ability of an atom to attract shared electron pair towards itself is called
📅IOM 2002
Q16.
Which of the following is the most electronegative atom?
📅IOM 1996
Q17.
The outermost electronic configuration of most electronegative atom is
📅IOM 1995
Q18.
The most homogenous family in the periodic table is
📅IOM 1995
Q19.
Moving from top towards bottom in periodic table
📅IOM 1995
Q20.
Electron attracting tendency of an element is called
📅BPKIHS
Q21.
Newland is famous for giving
📅BPKIHS
Q22.
Increasing order of size is
📅BPKIHS
Q23.
Correct order of electron affinity
📅BPKIHS
Q24.
In periodic table, the element which comes after calcium is
📅BPKIHS
Q25.
Mendeleev proposed his periodic law on the basis of
📅IOM 1992
Q26.
Which of the following represents the correct order of ionic radii?
📅MOE 2065
Q27.
Which sequence is correct if elements are arranged by ascending atomic number?
📅IOM 2008
Q28.
Atomic number 27 belongs to which block?
📅MOE 2008
Q29.
The character of hydrogen which is different from halogen is
📅Bangladesh 2008
Q30.
Atomic number of calcium is
📅IOM 2000
📚
ADDITIONAL QUESTIONS
Q1.
The first attempt to classify elements was made by
Q2.
Mendeleeff's periodic law is based on
Q3.
In the modern periodic table, elements are arranged in
Q4.
Eka-aluminium and Eka-silicon are known as
Q5.
Aluminium is diagonally related to
Q6.
If the valence shell electronic structure for an element is ns²np⁵, this element will belong to the group of
Q7.
An atom with atomic number 21 belongs to the category of
Q8.
Chloride of an element A gives neutral solution in water. In the periodic table, the element A belongs to
Q9.
Which one of the following belongs to representative element of a group in the periodic table?
Q10.
The lightest metal is
Q11.
Which of the following is the smallest cation?
Q12.
Which of the following is largest ion?
Q13.
Which of the following is smallest in size?
Q14.
Which of the following is not isoelectronic?
Q15.
Which one is the correct order of the size of the iodine species?
Q16.
The size of the following species increases in the order
Q17.
Al³⁺ has a lower ionic radius than Mg²⁺ because
Q18.
The energy required to remove an electron of a gaseous atom from its ground state is called
Q19.
Which of the following elements will have the lowest first ionisation energy?
Q20.
The first ionisation energy of lithium will be
Q21.
Which of the following electronic configuration corresponds to an element having lowest ionisation energy?
Q22.
Which has maximum first ionization potential?
Q23.
Which has lowest first ionization potential?
Q24.
Which has the highest second ionisation potential?
Q25.
Which one of the following elements has the highest ionisation energy?
Q26.
Which of the following order is correct for ionisation energy?
Q27.
The correct order of second ionisation potential of carbon, nitrogen, oxygen and fluorine is
Q28.
Of the following elements, which one has the highest electronegativity?
Q29.
Which of the following is the most electronegative?
Q30.
The electronegativity of Be is same as that of
Q31.
Which of the following represents the electronic configuration of d-block elements?
Q32.
Which one of the following elements has the maximum electron affinity?
Q33.
Electron affinity depends on
Q34.
Elements of which group form anions most readily?
Q35.
Oxidizing action increases from top to bottom in the following order
Q36.
Which is the weakest base among NaOH, Ca(OH)₂, KOH and Zn(OH)₂?
Q37.
Variable valency is generally exhibited by
Q38.
Paramagnetism is exhibited by molecules
Q39.
Which of the following ion is paramagnetic?
Q40.
Which of the following shows highest magnetic moment?
Q41.
Variable valency is due to
Q42.
Which one of the following electronic configuration is not possible?
Q43.
One would expect proton to have very large
Q44.
In the long form of the periodic table all the non-metals are placed in
Q45.
The long form of periodic table is based on
Q46.
The correct order of first ionization potential of the elements is
Q47.
Which of the following has maximum ionisation potential?
Q48.
With reference to ionization potential which one of the following sets is correct?
Q49.
Highest ionization potential is shown by
Q50.
The atomic radius of elements of which of the following series should be nearly the same?
Q51.
The decreasing order of the size of the following ions is
Q52.
The correct order of radii is
Q53.
Which has the smallest size?
Q54.
Which one of the following represents the correct order of size?
Q55.
On going from right to left in a period in the periodic table, the electronegativity of the elements
Q56.
The correct order of electron affinity of B, C, N and O is
Q57.
Fluorine has low electron affinity than chlorine because of
Q58.
Which of the following is not paramagnetic?
Q59.
Which of the following is not paramagnetic?
Q60.
Lanthanides contraction is due to increase in
Q61.
According to modern periodic law, variations in the properties of elements is related to their
Q62.
Increasing order of density is
Q63.
The lanthanide contraction is responsible for the fact that
Q64.
Increasing order of electron affinity is
Q65.
Outer electronic configuration of K, Cu and Cr are respectively
Q66.
Lanthanides and actinides are also called as
Q67.
Which of the following sets is of coinage metal?
Q68.
The group of elements in which the differentiating electron enters the antepenultimate shell are called
Q69.
Which is not soluble in water?
Q70.
Which of the following is second most electronegative element?
Q71.
In the periodic table, metals usually used as catalysts belong to
Q72.
Which is correctly arranged in increasing size?
Q73.
Ionization energy decreases down the group due to
Q74.
Increase in atomic size down the group is due to
Q75.
The only non-metal which is liquid at room temperature is
Q76.
Lanthanides contraction is due to increase in
Q77.
Lanthanides and Actinides are also called as
Q78.
In the periodic table, metals usually used as catalysts belong to
Q79.
Increase in atomic size down the group is due to
Q80.
The long form of the periodic table is based on
Q81.
The only non-metal which is liquid at room temperature is
📚
SAURAV QUESTION
Q1.
Technetium is named by Mendeleev as
📅2022
Q2.
Increasing order of metallic character
📅2022
Q3.
X belongs to group IIA and Y belongs to group VIIA. The formula of the compound formed by them is
📅2022
Q4.
Mg²⁺ is isoelectronic with
📅2021
Q5.
Electronic configuration having highest first I.E is
📅2017 Re-exam
Q6.
If the electronic configuration of an element ends at (n-1)d¹⁰ ns² then it falls in
📅2017
Q7.
The atom with highest 2ⁿᵈ ionization potential is
📅2016
Q8.
The VII A group of the periodic group is known as halogen family due to the property of forming
📅2016
Q9.
Which of the following has the highest ionization energy?
📅2014
Q10.
Which of the following electronic configuration given for some neutral atoms would be expected to have highest second ionization energy IE₂?
📅2010
Q11.
Arrange these in increasing Atomic Size
📅2000
Q12.
Moving from top towards bottom in periodic table
📅1995
Q13.
Al is diagonally related to
📅1994
Q14.
Which property of element is always a whole number?
📅2071 Mangsir 20
Q15.
Sodium and potassium have similar chemical and physical properties. This is best explained by the fact that both elements are
📅2070 Poush
Q16.
Which of the following elements have least value for electronegativity?
📅2069 Kartik
Q17.
The decreasing order of atomic radii for Be, Na and Mg is
📅2068 Kartik
Q18.
While moving from left to right in a periodic table which of the following variable decreases?
📅2067 Kartik
Q19.
Element with atomic number 19 belongs to which block of the periodic table?
📅2066 Poush
Q20.
Which of the following represents the correct order of ionic radii in aqueous medium?
📅2065 Marg
Q21.
Atomic number 27 belong to which block?
📅2065 Baisakh
Q22.
Oxidation number of Nitrogen ranges from
📅2055 Bhadra
Q23.
Which element was not included in Mendeleev's periodic table?
📅2018
Q24.
It is impossible for any two electrons in the same atom to have all the four quantum numbers identical. It states
📅2017
Q25.
Which one of the following ion has the largest radius?
📅2017
Q26.
Nitrogen is more stable than oxygen because of
📅2012
Q27.
In any given orbital electron fill up in increasing order of energy is it known as
📅2006
Q28.
In periodic table the element which comes after calcium is
📅2006
Q29.
On moving from top to down in group IV
📅2011
📚
HYDROGEN
Q1.
H2O2 is formed when a compound is reacted with H₂SO4. The compound is
📅2022
Q2.
Ortho and para isomer of hydrogen are separated by
📅2017
Q3.
Ortho and para hydrogen are distinguished by
📅2011
Q4.
Hydrogen cannot be obtained by
📅2005
Q5.
Calgon is used as a water softener is
📅2004
Q6.
Given colourless liquid will be determined whether it is water or not by
📅1998
Q7.
In which of the following compounds does hydrogen have negative valency?
📅1998
Q8.
Which of the following is not a water softener?
📅2070 Poush
Q9.
Calgon process for purification of water involves
📅2065 Baisakh
Q10.
The character of hydrogen which is different from halogen is
📅2009 MOE Banga
Q11.
The exhausted Zeolite in a water softener is regenerated with 10% solution of
📅2007
Q12.
The permanent hardness of water is due to dissolved
📅2006
Q13.
Which option is false regarding ortho and para hydrogen?
📅2018
Q14.
Froth floatation process is used for
📅2021
Q15.
Metals in german silver
📅2019
Q16.
Auto reduction is used to extract
📅2017 Re-exam
Q17.
During metallurgy fused metal is obtained during
📅2017
Q18.
Heating of pyrites to remove sulphur is
📅2015
Q19.
Hydrated Alumina is converted to anhydrous form by
📅2009
Q20.
Acid flux is
Q21.
Deposition of the layer of Zn over iron is called
Q22.
In the blast furnace iron ore is reduced by
📅2071 Mangsir
Q23.
Which of the following is the most abundant element in the Earth's Crust?
📅2069 Marg
Q24.
Leaching of ores is a process of
📅2067 Ashad
Q25.
Which of the following oxide can be reduced by carbon atom?
📅2063 Falgun
Q26.
Hall's process is used for
📅2017
Q27.
Froth floatation is applied for all except which ore
📅2010
Q28.
Abundance of the following elements in the Earth's crust is in order of
📅2007
📚
FROM SLIDES
Q1.
What is the screening effect in atoms?
Q2.
Which of the following factor increase screening effect?
Q3.
The effective nuclear charge
Q4.
In third row of periodic table from Na to Cl [MP PET 1986]
📅1986
Q5.
An atom with high electronegativity has [Kerala PMT 2003]
📅2003
Q6.
Between HF, HCl, HBr and HI, HF has the highest ionic character because [MP PMT 2007]
📅2007
Q7.
The most polar bond is [IIPMT 2005]
📅2005
Q8.
On going from right to left in a period in the periodic table the electronegativity of the elements [MP PET/PMT 1998; MP PMT]
📅1998
Q9.
Which one of the following represents the electronic configuration of the most electropositive element [AIIMS 1982; CPMT 1994; MP PMT 2000]
📅1982•1994•2000
Q10.
Which element having following electronic configurations has minimum ionisation potential [KCET 1991; CBSE PMT 1991; Pb. PET 1999; BHU 2000]
📅1991•1991•1999•2000
Q11.
A sudden large jump between the values of second and third ionisation energies of an element would be associated with the electronic configuration [CBSE PMT 1992; AFMC 1998; CPMT 1999; DCE 2006]
📅1992•1998•1999•2006