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Important Orders

High-yield increasing / decreasing ordering sequences — every entry is extracted and verified directly from the uploaded PDFs. Nothing here is generated or summarised.

207 document-verified orders

Alkali Metals

Ionisation Energy (I.E.)

Alkali Metals

Li > Na > K > Rb > Cs

Atomic Radius (A.R.)

Alkali Metals

Li < Na < K < Rb < Cs

Electron Gain Enthalpy (E.G.E.)

Alkali Metals

Li > Na > K > Rb > Cs

Electronegativity (EN)

Alkali Metals

Li > Na > K > Rb > Cs

Melting Point (M.P.)

Alkali Metals

Li > Na > K > Rb > Cs

Boiling Point (B.P.)

Alkali Metals

Li > Na > K > Rb > Cs

Density

Alkali Metals

Li < K < Na < Rb < Cs

Hydration Enthalpy

Alkali Metals

Li > Na > K > Rb > Cs

Standard Reduction Potential (SRP)

Alkali Metals

Na > K > Rb > Cs > Li

Reducing power in aqueous solution

Alkali Metals

Na < K < Cs < Rb < Li

Alkaline Earth Metals

Ionisation Energy (I.E.)

Alkaline Earth Metals

Be > Mg > Ca > Sr > Ra > Ba

Atomic Radius (A.R.)

Alkaline Earth Metals

Be < Mg < Ca < Sr < Ba

Electron Gain Enthalpy (E.G.E.)

Alkaline Earth Metals

Be (48) > Mg (40) > Ca (2.37) > Sr (-5.023) > Ba (-13.954)

Values in kJ/mol.

Electronegativity (EN)

Alkaline Earth Metals

Be > Mg > Ca > Sr > Ba

Melting Point (M.P.)

Alkaline Earth Metals

Be > Ca > Sr > Ba > Ra > Mg

Boiling Point (B.P.)

Alkaline Earth Metals

Be > Ba > Ca > Sr > Mg

Density

Alkaline Earth Metals

Ca < Mg < Be < Sr < Ba

Standard Reduction Potential (SRP)

Alkaline Earth Metals

Be > Mg > Ca > Sr > Ba

E° M^2+/M = -1.97, -2.36, -2.84, -2.89, -2.92 V.

Boron Family

Ionisation Energy (I.E.)

Boron Family

B > Tl > Ga > Al > In

Atomic Radius (A.R.)

Boron Family

B < Ga < Al < In < Tl

Electron Gain Enthalpy (E.G.E.)

Boron Family

B (26.898) < Tl (36.4) < In (37.043) < Ga (41) < Al (41.762)

Electronegativity (EN)

Boron Family

B > Tl > In > Ga > Al

Melting Point (M.P.)

Boron Family

B > Al > Tl > In > Ga

Boiling Point (B.P.)

Boron Family

B > Al > Ga > In > Tl

Density

Boron Family

B < Al < Ga < In < Tl

Carbon Family

Ionisation Energy (I.E.)

Carbon Family

C > Si > Ge > Sn > Pb

Atomic Radius (A.R.)

Carbon Family

C < Si < Ge < Sn < Pb

Electron Gain Enthalpy (E.G.E.)

Carbon Family

Si > C > Ge > Sn > Pb

Electronegativity (EN)

Carbon Family

C > Pb > Si ≈ Ge ≈ Sn

Melting Point (M.P.)

Carbon Family

C > Si > Ge > Pb > Sn

Boiling Point (B.P.)

Carbon Family

C > Si > Ge > Sn > Pb

Density

Carbon Family

Si < C < Ge < Sn < Pb

Nitrogen Family

Ionisation Energy (I.E.)

Nitrogen Family

N > P > As > Sb > Bi

Atomic Radius (A.R.)

Nitrogen Family

N < P < As < Sb < Bi

Electron Gain Enthalpy (E.G.E.)

Nitrogen Family

N < P < As < Sb < Bi

Electronegativity (EN)

Nitrogen Family

N > P > As > Sb ≈ Bi

Melting Point (M.P.)

Nitrogen Family

N < P < Bi < Sb < As

Boiling Point (B.P.)

Nitrogen Family

N < P < As < Bi < Sb

Density

Nitrogen Family

N < P < As < Sb < Bi

Oxygen Family

Ionisation Energy (I.E.)

Oxygen Family

O > S > Se > Te > Po

Atomic Radius (A.R.)

Oxygen Family

O < S < Se < Te < Po

Electron Gain Enthalpy (E.G.E.)

Oxygen Family

S > Se > Te > Po > O

Electronegativity (EN)

Oxygen Family

O > S > Se > Te > Po

Melting Point (M.P.)

Oxygen Family

O < S < Se < Po < Te

Boiling Point (B.P.)

Oxygen Family

O < S < Se < Po < Te

Density

Oxygen Family

O < S < Se < Te

Halogen Family

Ionisation Energy (I.E.)

Halogen Family

F > Cl > Br > I

Atomic Radius (A.R.)

Halogen Family

F < Cl < Br < I

Electron Gain Enthalpy (E.G.E.)

Halogen Family

Cl > F > Br > I

Electronegativity (EN)

Halogen Family

F > Cl > Br > I

Melting Point (M.P.)

Halogen Family

F < Cl < Br < I

Boiling Point (B.P.)

Halogen Family

F < Cl < Br < I

Density

Halogen Family

F < Cl < Br < I

Hydration Enthalpy

Halogen Family

F > Cl > Br > I

Bond Dissociation Enthalpy

Halogen Family

Cl₂ > Br₂ > F₂ > I₂

Noble Gases

Ionisation Energy (I.E.)

Noble Gases

He > Ne > Ar > Kr > Xe > Rn

Atomic Radius (A.R.)

Noble Gases

He < Ne < Ar < Kr < Xe

Electron Gain Enthalpy (E.G.E.)

Noble Gases

He < Xe < Ar = Kr < Ne

Positive value of EGE (48, 77, 96, 96, 116).

Melting Point (M.P.)

Noble Gases

He < Ne < Ar < Kr < Xe

Boiling Point (B.P.)

Noble Gases

He < Ne < Ar < Kr < Xe

Density

Noble Gases

He < Ne < Ar < Kr < Xe

d-Block (3d-series)

Atomic Radius (A.R.)

d-Block (3d-series)

Sc > Ti > Mn ≈ Zn > V > Cr > Cu > Fe > Co ≈ Ni

Sc is the lightest in the 3d series (density).

Ionisation Energy (IE1)

d-Block (3d-series)

Sc (631) < V (650) < Cr (653) < Ti (656) < Mn (717) < Ni (736) < Cu (745) < Co (758) < Fe (762) < Zn (906)

Ionisation Energy — Zn vs Cu

d-Block (3d-series)

IE₁: Zn > Cu ; IE₂: Cu > Zn

SRP (M^2+/M)

d-Block (3d-series)

Positive only for Cu, while negative for all 3d-series elements

SRP (M^3+/M^2+)

d-Block (3d-series)

Mn = 1.57 V, Fe = 0.77 V, Co = 1.97 V

Enthalpy of Atomisation

d-Block (3d-series)

V > Ti > Ni > Co > Fe > Cr > Cu > Sc > Mn > Zn

Values in kJ/mol.

Enthalpy of Hydration

d-Block (3d-series)

Cu ≈ Ni > Zn > Co > Fe > Cr > Mn > V > Ti

Values in kJ/mol.

Colour of Ions

d-Block (3d-series)

Sc³⁺ colourless; Ti⁴⁺ colourless; Ti³⁺ purple; V³⁺ green; V²⁺ violet; Cr³⁺ violet; Mn³⁺ violet; Mn²⁺ pink; Fe³⁺ yellow; Fe²⁺ green; Co³⁺/Co²⁺ blue-pink; Ni²⁺ green; Cu²⁺ blue; Zn²⁺ colourless

Inorganic In My Pocket

Decreasing ionic size

Inorganic In My Pocket

O^2- > F^- > Na⁺ > Mg²⁺

All four are isoelectronic (1s² 2s² 2p⁶); nuclear charge increases Mg > Na > F > O.

Increasing acidic property

Inorganic In My Pocket

Na₂O₂ < MgO < ZnO < P₂O₅

Acidic character increases with electronegativity: Na < Mg < Zn < P.

Increasing bond length

Inorganic In My Pocket

N₂ < O₂ < F₂ < Cl₂

N₂ triple bond, O₂ double bond, F₂ and Cl₂ single bonds.

Increasing size

Inorganic In My Pocket

Ca²⁺ < Cl^- < S^2-

Isoelectronic species; more protons → more attraction → smaller radius.

Increasing acid strength

Inorganic In My Pocket

HClO < HClO₂ < HClO₃ < HClO₄

More the oxidation number of the central atom, more acidic.

Increasing oxidation number of iodine

Inorganic In My Pocket

HI < I₂ < ICl < HIO₄

Oxidation states of I are -1, 0, +1, +7 respectively.

Increasing thermal stability

Inorganic In My Pocket

HOCl < HOClO < HOClO₂ < HOClO₃

Increasing bond enthalpy

Inorganic In My Pocket

F₂ < Cl₂ < O₂ < N₂

F₂ has lower bond enthalpy than Cl₂ due to greater non-bonding electron repulsion in F₂.

Increasing acidic character

Inorganic In My Pocket

SiO₂ < CO₂ < N₂O₅ < SO₃

Increasing electronegativity makes the oxide more acidic.

Increasing ionic size

Inorganic In My Pocket

Mg²⁺ < Na⁺ < F^- < O^2-

Increasing strength of hydrogen bonding (H···H–X)

Inorganic In My Pocket

S < Cl < N < O < F

Negative charge on X increases with electronegativity, strengthening H-bonding.

Increasing ionic radii in water

Inorganic In My Pocket

Cs⁺ < Rb⁺ < K⁺ < Na⁺ < Li⁺

Smaller ions are more heavily hydrated, so hydrated size is larger.

Increasing molar conductivity in water

Inorganic In My Pocket

Li⁺ < Na⁺ < K⁺ < Rb⁺ < Cs⁺

Li⁺ heavily hydrated → lowest mobility; Cs⁺ least hydrated → highest mobility.

Increasing reactivity with water

Inorganic In My Pocket

Li < Na < K < Rb < Cs

Reactivity increases down group 1.

Increasing basic nature of hydroxides

Inorganic In My Pocket

LiOH < NaOH < KOH < RbOH < CsOH

Increasing covalent character

Inorganic In My Pocket

LiCl < LiBr < LiI

Smaller Li⁺ polarises the larger anion more → greater covalent character.

Increasing ionic character

Inorganic In My Pocket

BeCl₂ < MgCl₂ < CaCl₂ < BaCl₂ < SrCl₂

Increasing solubility

Inorganic In My Pocket

BaCO₃ < CaCO₃ < MgCO₃ < BeCO₃

Down the group, lattice energy changes little while hydration decreases, so solubility decreases.

Increasing solubility

Inorganic In My Pocket

Be(OH)₂ < Mg(OH)₂ < Ca(OH)₂ < Ba(OH)₂

Increasing basicity

Inorganic In My Pocket

Be(OH)₂ < Mg(OH)₂ < Ca(OH)₂ < Ba(OH)₂

Increasing hydration of ions

Inorganic In My Pocket

Ba²⁺ < Sr²⁺ < Ca²⁺ < Mg²⁺ < Be²⁺

Hydration decreases with increasing ionic size.

Increasing reactivity with water

Inorganic In My Pocket

Be < Mg < Ca < Sr < Ba

Increasing reactivity towards air

Inorganic In My Pocket

Be < Mg < Ca < Sr < Ba

Increasing solubility

Inorganic In My Pocket

BaSO₄ < SrSO₄ < CaSO₄ < MgSO₄ < BeSO₄

Hydration dominates over lattice energy.

Increasing ionic character

Inorganic In My Pocket

BCl₃ < AlCl₃ < GaCl₃

Increasing strength of Lewis acid

Inorganic In My Pocket

BF₃ < BCl₃ < BBr₃

pπ-pπ back-bonding is maximum in BF₃ and falls to BBr₃, so acceptor tendency increases.

Increasing strength of Lewis acid

Inorganic In My Pocket

InCl₃ < GaCl₃ < AlCl₃

Increasing reducing power

Inorganic In My Pocket

PbCl₂ < SnCl₂ < GeCl₂

Stability of +II increases up group 14 (inert-pair effect).

Increasing oxidizing power

Inorganic In My Pocket

GeCl₄ < SnCl₄ < PbCl₄

Stability of +IV decreases up group 14 (inert-pair effect).

Increasing basic character

Inorganic In My Pocket

SbH₃ < AsH₃ < PH₃

Increasing thermal stability

Inorganic In My Pocket

SbH₃ < AsH₃ < PH₃ < NH₃

Increasing acidic strength

Inorganic In My Pocket

H₃SbO₄ < H₃AsO₄ < H₃AsO₃ < HNO₃

Increasing solubility in water

Inorganic In My Pocket

H₃SbO₄ < H₃AsO₄ < H₃AsO₃ < HNO₃

Increasing order of +5 oxidation state

Inorganic In My Pocket

Bi < Sb < As < P < N

Increasing stability of hydrides

Inorganic In My Pocket

H₂Te < H₂Se < H₂S < H₂O

Increasing poisonous nature

Inorganic In My Pocket

H₂S < H₂Se < H₂Te < H₂Po

Increasing acidic strength

Inorganic In My Pocket

H₂O < H₂S < H₂Se < H₂Te

Larger X → weaker H–X bond → H⁺ lost more easily.

Increasing strength of oxoacids

Inorganic In My Pocket

H₂TeO₃ < H₂SeO₃ < H₂SO₃

Increasing stability of oxoacids

Inorganic In My Pocket

H₂TeO₃ < H₂SeO₃ < H₂SO₃

Increasing stability of oxoacids

Inorganic In My Pocket

H₂TeO₄ < H₂SeO₄ < H₂SO₄

Increasing stability of oxoacids

Inorganic In My Pocket

H₂TeO₄ < H₂SeO₄ < H₂SO₄

Increasing electron affinity

Inorganic In My Pocket

Cl > F > Br > I

Increasing reducing power

Inorganic In My Pocket

HF < HCl < HBr < HI

Increasing affinity for hydrogen

Inorganic In My Pocket

I₂ < Br₂ < Cl₂ < F₂

Increasing acidity

Inorganic In My Pocket

HF < HCl < HBr < HI

Increasing boiling point

Inorganic In My Pocket

HCl < HBr < HI < HF

Anomalous behaviour of HF is due to hydrogen bonding.

Increasing stability

Inorganic In My Pocket

HFO₃ < HClO₃ < HBrO₃ < HIO₃

Increasing covalent character

Inorganic In My Pocket

TiCl₂ < TiCl₃ < TiCl₄

Higher oxidation state → more polarisation → more covalency.

Increasing magnetic moment

Inorganic In My Pocket

Zn²⁺ < Ti³⁺ < Ni²⁺ < Co²⁺ < Cr²⁺

Unpaired electrons: Ti³⁺ 1, Ni²⁺ 2, Co²⁺ 3, Cr²⁺ 4, Zn²⁺ 0.

Increasing ionic character

Inorganic In My Pocket

VCl₄ < VCl₃ < VCl₂

Decreasing oxidation state increases ionic character.

Increasing basic characteristics

Inorganic In My Pocket

CO₂ < B₂O₃ < BeO < Li₂O

Increasing electronegativity

Inorganic In My Pocket

As < P < S < Cl

Increasing acidity

Inorganic In My Pocket

HOI < HOBr < HOCl

Increasing thermal stability

Inorganic In My Pocket

HI < HBr < HCl < HF

Increasing bond enthalpy

Inorganic In My Pocket

F₂ < Cl₂ < O₂ < N₂

Increasing melting point

Inorganic In My Pocket

CaI₂ < CaBr₂ < CaCl₂ < CaF₂

Increasing oxidizing power

Inorganic In My Pocket

Te < Se < S < O

Increasing oxidizing power

Inorganic In My Pocket

I < Br < Cl < F

Increasing single bond strength

Inorganic In My Pocket

N—N < O—O < F—F

Increasing stability of hydrides

Inorganic In My Pocket

CsH < KH < NaH < LiH

Increasing pH of aqueous solution

Inorganic In My Pocket

LiCl > MgCl₂ > BeCl₂ > AlCl₃

Larger charge and smaller size favour more hydrolysis → more free H⁺ → lower pH.

Increasing acidic oxide

Inorganic In My Pocket

MgO < Al₂O₃ < SiO₂ < P₄O₁₀

Increasing basicity

Inorganic In My Pocket

I^- < Br^- < Cl^- < F^-

Stronger the acid, weaker its conjugate base.

Increasing basic strength

Inorganic In My Pocket

F^- < OH^- < NH₂^- < CH₃^-

More electronegative the atom, lesser its tendency to donate a lone pair.

Increasing thermal stability

Inorganic In My Pocket

BeCO₃ < MgCO₃ < CaCO₃ < BaCO₃

Larger cation → lower polarising power → more stable compound.

Increasing paramagnetism

Inorganic In My Pocket

Ca < Al < O < N

Paramagnetism increases with number of unpaired electrons.

Increasing ionic character

Inorganic In My Pocket

LiBr < NaBr < KBr < RbBr < CsBr

Greater electronegativity difference → greater ionic character.

Increasing hydration energy

Inorganic In My Pocket

Ba²⁺ < Sr²⁺ < Ca²⁺ < Mg²⁺ < Be²⁺

Smaller size → more hydration energy.

Increasing bond angle

Inorganic In My Pocket

AsH₃ < PH₃ < NH₃

Larger / less electronegative central atom decreases bond-pair repulsion.

Increasing bond angle

Inorganic In My Pocket

AsH₃ < PH₃ < NH₃

Increasing bond angle

Inorganic In My Pocket

H₂Se < H₂S < H₂O

Increasing bond angle

Inorganic In My Pocket

NF₃ < NCl₃

Bond-pair repulsion in NF₃ is less than in NCl₃.

Increasing bond angle

Inorganic In My Pocket

NO₂⁺ < NO₂ < NO₂^-

Increasing bond angle

Inorganic In My Pocket

NF₃ < NH₃

Lesser bond-pair repulsion in NF₃.