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JEE 2024: Periodic Properties Class 11 One Shot | 1 Month 11th Done | JEE Chemistry #jeepreparation

Vedantu JEE English・96 minutes read

Understanding the history and key topics of the classification of elements and periodic properties in chemistry is crucial for exam preparation, covering Mendeleev's contributions, periodic trends, and the modern periodic table based on atomic number and electronic configuration. Various factors like atomic size, ionization energy, electron gain enthalpy, electronegativity, and bonding are explored to understand the properties and behavior of different elements across the periodic table.

Insights

  • Understanding the historical evolution of the periodic table, from Mendeleev's organization based on atomic weights to Mosley's modern table based on atomic number, is crucial for comprehending the classification of elements and their properties.
  • The periodic table's structure, including the arrangement of elements in periods and groups, plays a vital role in predicting properties and trends such as atomic size, ionization energy, electron affinity, and electronegativity, essential for exam preparation.
  • The concept of shielding effect, which involves inner electrons reducing the effective nuclear charge felt by outer electrons, influences atomic size, ionization energy, and electron affinity trends across the periodic table, impacting the chemical behavior of elements significantly.

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Recent questions

  • What is the significance of Mendeleev's periodic table?

    Mendeleev's periodic table organized elements by atomic weights, predicting properties of undiscovered elements. He arranged elements with similar properties in columns and rows, leaving gaps for future discoveries. Mendeleev's adjustments improved accuracy, influencing the modern periodic table based on atomic number.

  • How does the modern periodic table differ from Mendeleev's?

    The modern table is based on atomic number, explaining periodicity through electron configuration. It consists of 18 groups and 7 periods, classifying elements by outermost shells. Mendeleev's table focused on atomic weights and properties, while the modern table emphasizes atomic number and electronic structure.

  • What are the key trends in the periodic table?

    Periodic trends include ionization enthalpy, electron gain enthalpy, and electronegativity. Physical properties like melting points and densities vary across periods and groups. Understanding these trends aids in predicting element behaviors and properties.

  • How are elements classified in the periodic table?

    Elements are grouped into S, P, D, and F blocks based on electron configurations. Lanthanides and actinides are inner transition elements within the D block. The table's structure helps in identifying elements and understanding their properties.

  • Why is the concept of shielding effect important in chemistry?

    Shielding effect explains how inner electrons shield outer electrons from the nucleus, affecting atomic size and properties. It influences effective nuclear charge, ionization energy, and electron affinity. Understanding shielding effect aids in comprehending atomic behaviors and trends in the periodic table.

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Summary

00:00

Evolution and Importance of Periodic Elements

  • Chapter: Classification of Elements and Periodic Properties is crucial for JEE Mains and Advanced exams, foundational for inorganic chemistry chapters like coordination compounds, s block, p block, and dnf block.
  • Understanding the history of periodic elements evolution is essential, from the initial days with fewer elements to the current 118 elements discovered.
  • Key topics in the chapter include modern periodic law, periodic table structure, nomenclature of elements, electronic configurations (SPDF blocks), and types of elements.
  • Detailed study of s block, p block, d block, and f block elements is necessary, as these chapters are covered in both 11th and 12th standards.
  • Learning about metals, nonmetals, and metalloids, along with periodic trends and properties of elements, is crucial for exam preparation.
  • Focus on trends in physical properties like ionization enthalpy, electron gain enthalpy, and electronegativity, as well as chemical properties like oxidation state and reactivity.
  • Historical overview includes Doberiner's grouping of elements based on atomic mass, Newland's Law of Octaves, and Lothar Meyer's atomic volume vs. atomic mass graph.
  • Mendeleev's contribution as the father of the periodic table, organizing elements based on atomic weights and proposing physical properties as periodic functions of atomic masses.
  • Mendeleev's periodic table had seven rows and nine columns, with groups named from 1 to 7 and a zero group, organizing elements like hydrogen, lithium, sodium, potassium, fluorine, chlorine, and manganese.
  • Despite its accuracy, Mendeleev's table had a flaw of placing three elements in the same column, highlighting the importance of his contributions to the periodic table's development.

16:31

"Mendeleev's Periodic Table Predicts Element Properties"

  • Mendeleev's periodic table arranges elements by increasing atomic weights, showing similar properties at regular intervals in vertical columns and horizontal rows.
  • Elements with similar natures are grouped together in vertical columns based on atomic weight.
  • Mendeleev adjusted the order of atomic weights to match the physical and chemical properties of elements.
  • He left empty spaces in the table for undiscovered elements, which were later found to fit his predictions.
  • Predicted elements like eka aluminum and eka silicon were later discovered with atomic masses close to his predictions.
  • The densities and melting points of predicted elements closely matched those of the discovered elements.
  • Mendeleev corrected doubtful atomic weights, like for beryllium, leading to a more accurate classification.
  • The modern periodic table, developed by Henry Mosley, is based on atomic number rather than atomic weight.
  • The modern table explains the periodicity of elements based on their atomic number and electronic configuration.
  • The modern table includes 18 groups and 7 periods, with elements classified based on their outermost electron shells.

31:59

"Periodic Table: Elements, Orbitals, Naming, Screening"

  • The periodic table consists of eight elements in a short period, starting from sodium (11) and ending at argon (18).
  • The fourth period includes the filling of 4S, 3D, and 4B orbits, totaling 18 electrons from potassium (19) to Krypton (36).
  • The fifth period spans from rubidium (37) to Xenon (54), with 5S, 4D, and 5P orbitals, also totaling 18 electrons.
  • The sixth period involves 6S, 4F, 5D, and 6P orbitals, accommodating 32 elements from cesium (55) to radon (86).
  • The seventh period, from francium (87) to organism (118), includes 5F, 6D, and 7P orbitals, totaling 32 elements.
  • A controversy arose over naming elements, like rutherfordium, resolved by IUPAC to standardize nomenclature.
  • The periodic table is divided into S, P, D, and F blocks, with S and P blocks as representative and D block as transition elements.
  • Lanthanides (57-71) and actinides (89-103) within the D block are termed inner transition elements.
  • IUPAC's naming rule post-atomic number 100 involves deriving element names from digit roots, as demonstrated with examples.
  • Screening effect in atoms, akin to a crowded scenario, explains how inner electrons shield outer electrons from the nucleus, affecting the effective nuclear charge.

47:57

Atomic Radius Calculation and Factors Explained

  • Gossip about lions and tigers on the road in Silkboard with heavy traffic was shared.
  • Calculation of Z effective charge for an electron using shells and electrons present.
  • Step-by-step calculation of Z effective charge for a 4S electron in Mn (Z=25).
  • Factors affecting shielding effect: number of inertial electrons, orbital shape (S>P>D>F).
  • Explanation of atomic radius measurement challenges and methods.
  • Types of atomic radius: covalent, metallic, and Van Der Waals.
  • Calculation of bond length using covalent radii and electronegativity difference.
  • Factors affecting atomic radius: increases with more shells, largest in Group 1 elements.
  • Definition and impact of effective nuclear charge on atomic size.
  • Increase in nuclear charge leads to a decrease in atomic size due to electron attraction.

01:07:00

Atomic size trends in periodic table.

  • More protons mean more electrons; nuclear charge increases, atomic size decreases.
  • Shielding effect: inner electrons act as curtains, preventing nucleus-electron interaction, increasing atomic radius.
  • Multiplicity of bonds: more bonds lead to shorter bond lengths.
  • Periodic table: atomic size decreases across a period, increases down a group.
  • Exceptions in group 13: atomic radius increases from Boron to Aluminum, remains constant from Aluminum to Gallium due to poor shielding effect of 3D electrons.
  • Transition series: covalent radii decrease left to right, increase slightly towards the end.
  • Maximum atomic radius: magnesium has the largest atomic radius among aluminum, silicon, phosphorus, and magnesium.
  • Ionic radius: cations are smaller due to more protons, anions are larger due to more electrons.
  • Example with titanium and manganese ions: 4+ titanium is larger than 7+ manganese.
  • Isoelectronic species: comparing sizes of ions with different charges.

01:23:42

Isoelectronic Species and Ionization Energy Trends

  • Isoelectronic species have the same number of electrons but differ in nuclear charge.
  • Examples include N3 minus, O2 minus, F minus, Mg 2 plus, Na plus, and Al 3 plus.
  • The ionic radius decreases as the nuclear charge and force of attraction increase.
  • The correct order of ionic radii is Al 3 plus, Mg 2 plus, Na plus, F minus, O2 minus, N3 minus.
  • Potassium ion is relatively bigger than chloride ion if they are isoelectronic.
  • Ionization energy is the energy needed to remove an electron from an atom.
  • Ionization energy increases as you move from left to right in a period.
  • Atomic size is inversely proportional to ionization energy.
  • Nuclear charge is directly proportional to ionization energy.
  • Screening effect decreases ionization energy as inner orbital electrons shield outermost electrons.

01:39:43

Atomic Properties and Electron Behavior in Chemistry

  • Oxygen, magnesium, and aluminum have lower ionization energy due to their atomic numbers.
  • Electron gain enthalpy is the energy released when an electron is added to an atom's valence shell.
  • Factors affecting electron gain enthalpy include effective nuclear charge and electron affinity.
  • Atomic radius is inversely proportional to electron affinity.
  • Screening effect decreases electron affinity as protons are unable to attract electrons.
  • Half-filled and fully filled electronic configurations are stable and resist accepting extra electrons.
  • Across a period, electron gain enthalpy becomes more negative with increasing atomic number.
  • Electronegativity is the ability of an atom to attract shared electrons in a bond.
  • Mulliken and Pauling scales measure electronegativity based on ionization potential and bond enthalpy.
  • Factors affecting electronegativity include atomic size, effective nuclear charge, and hybridization state.

01:56:03

Ionic vs Covalent Bonds: Oxide Electronegativity Analysis

  • If the ionic percentage of a compound is less than 50%, it leans towards a covalent bond. The electronegativity of an oxide determines its nature: if greater than 2.3, it's basic; if equal to 2.3, it's amphoteric; if less than 2.3, it's acidic. This calculation concludes the session, with additional tips and tricks to be covered in a separate video.
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