ChemistryClassification of Elements and Periodicity in Properties1 / 12
QuestionState the formula — Moseley's Law
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Answer1 / 12
Moseley's Lawν=a(Z−b)Relates the frequency of emitted X-rays to the atomic number of an element.applies whena is a proportionality constant and b is a screening constant.moseleyx-rayjee-advanced
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All 12 Classification of Elements and Periodicity in Properties formulas
01
Modern Periodic Table and Law
1 formula
Moseley's Law
ν=a(Z−b)
Relates the frequency of emitted X-rays to the atomic number of an element.
applies whena is a proportionality constant and b is a screening constant.
moseleyx-rayjee-advanced
02
Periodic Trends in Properties
11 formulas
Acidic Oxide Reaction with Water
Cl2O7+H2O→2HClO4
Demonstrates the highly acidic nature of extreme right-side non-metallic oxides.
applies whenStandard test reaction for Group 17 non-metal oxides.
oxideacidicreactionworked-example
Allred-Rochow Electronegativity
χAR=0.359r2Zeff+0.744
Electronegativity based on the electrostatic force exerted by the effective nuclear charge on valence electrons.
applies whenr is the covalent radius in Angstroms (A˚).
electronegativityallred-rochowjee-advanced
Basic Oxide Reaction with Water
Na2O+H2O→2NaOH
Demonstrates the highly basic nature of extreme left-side metallic oxides.
applies whenStandard test reaction for Group 1 metal oxides.
oxidebasicreactionworked-example
Thermodynamic Electron Affinity Relation
ΔegH=−Ae−25RT
Relationship between electron gain enthalpy and electron affinity at a given temperature.
applies whenAssumes ideal gas behavior for the added electron; T is temperature.
electron-affinitythermodynamics
Electron Gain Enthalpy
X(g)+e−→X−(g)
Reaction and enthalpy change when an electron is added to a neutral gaseous atom.
applies whenIsolated gaseous atom.
electron-gainenthalpy
First Ionization Enthalpy
X(g)→X+(g)+e−
Reaction and enthalpy change for removing the first electron from an isolated gaseous atom.
applies whenIsolated gaseous atom in its ground state.
ionizationenthalpyfirst
Second Ionization Enthalpy
X+(g)→X2+(g)+e−
Reaction and enthalpy change for removing the second most loosely bound electron.
applies whenPositive isolated gaseous ion.
ionizationenthalpysecond
Ionization Enthalpy of Hydrogen
ΔiH=(E∞−E1)×NA=2.18×10−18NA J/mol
Calculation of the ionization enthalpy of 1 mole of atomic hydrogen from its ground state energy.
applies whenDerived from E1=−2.18×10−18 J.
ionizationhydrogenexercise
Mulliken Electronegativity
χM=2IE+EA
Electronegativity based on the arithmetic mean of ionization energy and electron affinity.
applies whenIE and EA are in electron-volts (eV) per atom.
electronegativitymullikenjee-advanced
Pauling Electronegativity Difference
∣χA−χB∣=0.208ΔA−B
Calculates the difference in electronegativity between two bonded atoms using bond dissociation energies.
applies whenΔA−B=EA−B−EA−AEB−B. Energies are in kcal/mol.
electronegativitypaulingjee-advanced
Effective Nuclear Charge
Zeff=Z−σ
Net positive charge experienced by an electron in a multi-electron atom.
applies whenσ is the shielding or screening constant calculated via Slater's rules.