Development of Atomic Theory and Classification
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Questions and Answers

What was John Dalton’s major contribution to the classification of elements?

  • He proposed the Law of Octaves.
  • He classified elements into groups based on their properties.
  • He suggested that all elements were multiples of Oxygen.
  • He defined a way to determine atomic weights and rearranged a list in increasing order of mass. (correct)

    • What observation did William Prout make about atomic weights?

  • They were all equal to the weight of Oxygen.
  • They followed the Law of Octaves.
  • They could not be simplified.
  • They seemed to be multiples of Hydrogen. (correct)

    • What method did Johann Wolfgang Döbereiner use to classify elements?

  • He arranged them based on their density.
  • He classified them based on their atomic numbers.
  • He grouped them into pairs based on specific properties.
  • He organized them into triads with a middle element displaying intermediate properties. (correct)

    • How did John Newlands contribute to the understanding of element classification?

    <p>He proposed the Law of Octaves based on periodic trends.</p> Signup and view all the answers

    What was a notable feature of Dmitri Mendeleev's periodic table?

    <p>It organized elements by atomic mass and classified them by properties.</p> Signup and view all the answers

    Why was Mendeleev able to address discrepancies in the periodic table?

    <p>He assumed elements were missing and proposed reordering.</p> Signup and view all the answers

    What was the primary focus of John Dalton's atomic theory?

    <p>The atomic nature and weights of elements.</p> Signup and view all the answers

    How did Lavoisier influence John Dalton's work?

    <p>By providing a method for determining atomic weights.</p> Signup and view all the answers

    Which category of elements is primarily located on the right side of the periodic table?

    <p>Nonmetals</p> Signup and view all the answers

    What is a characteristic of nonmetals?

    <p>Dull appearance</p> Signup and view all the answers

    Which of the following elements is considered a metalloid?

    <p>Silicon (Si)</p> Signup and view all the answers

    What is a distinguishing feature of metalloids?

    <p>They exhibit intermediate properties between metals and nonmetals.</p> Signup and view all the answers

    Which elements are considered part of the Lanthanide and Actinide series?

    <p>Elements that have their last electrons in the f orbital.</p> Signup and view all the answers

    Which of the following statements about metals is true?

    <p>Metals tend to lose electrons to form cations.</p> Signup and view all the answers

    How do nonmetals generally behave in terms of electron configuration?

    <p>They tend to gain electrons.</p> Signup and view all the answers

    What characteristic is typical of metalloids?

    <p>They can be lustrous or dull.</p> Signup and view all the answers

    What does the effective nuclear charge represent?

    <p>The net positive charge experienced by valence electrons</p> Signup and view all the answers

    How does atomic radius change as you move down a group in the periodic table?

    <p>Atomic radius increases</p> Signup and view all the answers

    What is the typical range of atomic radii for most atoms?

    <p>30 to 300 pm</p> Signup and view all the answers

    Which factor contributes to an increase in effective nuclear charge?

    <p>Increase in the number of protons</p> Signup and view all the answers

    What determines the ionic radius of an element?

    <p>The number of electrons surrounding the nucleus</p> Signup and view all the answers

    Why is it important to know the atomic radius in applications?

    <p>Atoms can be modeled as spheres</p> Signup and view all the answers

    How do the forces of attraction and repulsion affect effective nuclear charge?

    <p>Attraction by protons increases net charge experienced by valence electrons</p> Signup and view all the answers

    What does an increase in valence electrons do to effective nuclear charge?

    <p>Increases the effective nuclear charge</p> Signup and view all the answers

    What occurs when electrons are removed from a parent atom to form a positive ion?

    <p>The atomic radius decreases.</p> Signup and view all the answers

    How does adding electrons to a parent atom affect its ionic radius?

    <p>It results in a higher atomic radius.</p> Signup and view all the answers

    How is atomic radius defined in isoelectronic species?

    <p>It decreases with a higher effective nuclear charge.</p> Signup and view all the answers

    What defines ionization energy?

    <p>The energy needed to remove an electron from an atom.</p> Signup and view all the answers

    What effect does the addition of an electron have on the energy associated with electron affinity?

    <p>It releases energy due to attractive forces.</p> Signup and view all the answers

    In what way does electronegativity influence atomic interactions?

    <p>It refers to the ability to attract electron pairs in covalent bonds.</p> Signup and view all the answers

    Which statement accurately describes the relationship between atomic radius and ionization energy?

    <p>Smaller atomic radius typically correlates with higher ionization energy.</p> Signup and view all the answers

    What can be inferred about the trend in ionic radius when comparing negative ions to positive ions?

    <p>Negative ions have larger ionic radii than positive ions.</p> Signup and view all the answers

    What describes metallic character in terms of electron behavior?

    <p>The tendency to lose electrons to form a cation.</p> Signup and view all the answers

    Which of the following statements about Group 1 metals is true?

    <p>They are very soft and have one valence electron.</p> Signup and view all the answers

    What trend is observed regarding the reactivity of Group 1 elements with water?

    <p>Reactivity increases as ionization energy decreases.</p> Signup and view all the answers

    What defines non-metallic character?

    <p>The tendency to gain electrons and form an anion.</p> Signup and view all the answers

    Which of the following statements about halogens is true?

    <p>Halogens are highly electronegative and exist in all three states of matter.</p> Signup and view all the answers

    Why are pure alkali metals stored submerged in oils?

    <p>To prevent oxidation and reactivity with water.</p> Signup and view all the answers

    Which of the following is NOT a property of Group 1 metals?

    <p>They are very hard metals.</p> Signup and view all the answers

    What is true about the reactivity of halogens?

    <p>Halogens can be harmful and are highly reactive due to high electron affinity.</p> Signup and view all the answers

    Study Notes

    Development of Atomic Theory

    • John Dalton (1810) built on Lavoisier's work, determining atomic weights and rearranging elements by mass.
    • Dalton excluded light and energy as elements.
    • William Prout (1815) recognized atomic weights were multiples of Hydrogen, simplifying its weight to 1 unit.

    Classification of Elements

    • Johann Wolfgang Döbereiner (1817) classified elements into triads based on similar properties: the middle element had intermediate characteristics.
    • John Newlands (1864) proposed the Law of Octaves, grouping elements into eight sets, indicating periodicity in properties.

    Mendeleev's Periodic Table

    • Dmitri Mendeleev (1869) created a table ordering elements by atomic mass and properties; discrepancies recognized due to undiscovered elements.
    • Mendeleev's classification involved groups (columns) and periods (rows).

    Element Categories

    • Elements are divided into metals, nonmetals, and metalloids.
    • Nonmetals are found on the right, characterized by brittleness, dull appearance, low melting points, and tendency to gain electrons.
    • Metalloids lie between metals and nonmetals, showing intermediate properties, e.g., Silicon (Si) and Tellurium (Te).

    Lanthanide and Actinide Series

    • Lanthanide and actinide series are placed at the bottom of the periodic table, linked to their f orbital electron configurations.

    Blocks in the Periodic Table

    • Elements are categorized into blocks (s, p, d, f) based on outermost electron orbital shapes.
    • Effective Nuclear Charge (ENC) is the net positive charge felt by valence electrons, influenced by proton and core electron interactions.
    • ENC increases with the number of protons and valence electrons.
    • Atomic radius is semi-defined as the Van der Waals distance between adjacent nuclei, typically ranging from 30 to 300 picometers.
    • Atomic radius increases down a group and decreases across a period.
    • Ionic radius varies with ionization: removing electrons (for positive ions) results in a smaller radius, while adding electrons (for negative ions) increases radius.

    Isoelectronic Species

    • For isoelectronic species, the radius decreases with increased effective nuclear charge.
    • Ionization energy is the energy required to remove an electron from an atom's outer layer.
    • Lower ionization energies lead to a higher tendency to lose electrons.
    • Electron affinity measures the energy released when an electron is added to an atom, revealing tendencies for an atom to form anions.
    • Electronegativity is the ability of an atom to attract electron pairs in covalent bonds.
    • Metallic character corresponds to the tendency to lose electrons; non-metallic character relates to the tendency to gain electrons.

    Group Properties

    • Group 1 alkali metals have high reactivity, characterized by a single valence electron and soft metal structure.
    • Alkali metals form compounds with water, reacting violently and are stored submerged in oil due to their reactivity.

    Group 17: Halogens

    • Halogens, meaning "salt makers," are highly electronegative and reactive, forming salts with metals.
    • They exist in all three states: gases (F, Cl), liquids (Br), and solids (I, At, Ts) at room temperature.

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    IB Chemistry Module 1.3: The Periodic Table - PDF

    Description

    Explore the evolution of atomic theory from Dalton to Mendeleev's periodic table. This quiz covers key concepts such as classification of elements and distinctions between metals, nonmetals, and metalloids. Test your understanding of the foundations of chemistry and element categorization.

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