Year 10 Chemistry - Periodic Table
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Questions and Answers

Who is credited with arranging elements by atomic number?

  • Henry Moseley (correct)
  • Antoine Lavoisier
  • Dmitri Mendeleev
  • Johann Dobereiner
  • What happens to the atomic radius when moving down a group in the periodic table?

  • It fluctuates
  • It increases (correct)
  • It decreases
  • It remains the same
  • What is the result of an increased positive charge in the nucleus when moving from left to right across a period?

  • The atomic radius increases
  • The electron shells are pushed away from the nucleus
  • The number of protons decreases
  • The electron shells are drawn closer to the nucleus (correct)
  • Who is credited with grouping elements into metals, non-metals, and semimetals?

    <p>Antoine Lavoisier</p> Signup and view all the answers

    What is observed when arranging elements by atomic mass?

    <p>A periodic trend</p> Signup and view all the answers

    What is the result of an increase in electron shells when moving down a group?

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

    Which direction across a period in the periodic table do reactivity trends for metals increase?

    <p>Right to left</p> Signup and view all the answers

    What is the reason for the increase in reactivity of metals down a group?

    <p>Larger atomic radius</p> Signup and view all the answers

    What is the characteristic of metals that makes them good conductors of heat and electricity?

    <p>Delocalised electrons</p> Signup and view all the answers

    What is the primary factor that determines the rate of reaction according to the collision theory?

    <p>All of the above</p> Signup and view all the answers

    Which of the following is a characteristic of nonmetals?

    <p>Low melting and boiling points</p> Signup and view all the answers

    What is the property of semimetals that is intermediate between metals and nonmetals?

    <p>Average thermal conductivity</p> Signup and view all the answers

    Study Notes

    Contributions of Scientists

    • Johann Dobereiner discovered triads of elements with chemical similarities.
    • John Newlands arranged elements by atomic mass and observed periodic trends and families of elements.
    • Dmitri Mendeleev grouped elements by physical properties, observed periodic trends and similarities in grouping, and made predictions for yet to be discovered elements.
    • Henry Moseley arranged elements by atomic number.
    • Antonine Lavoisier grouped elements into metals, non-metals, and semimetals.

    The Structure of the Periodic Table

    • Atomic radius increases down a group and from right to left across a period.
    • When moving down a group, the number of electron shells increases, causing the outermost electrons to be farther from the nucleus, increasing the width of the atom.
    • When moving from left to right across a period, the number of protons increases, resulting in a stronger positive charge in the nucleus, which pulls the outermost electrons in, making the atom smaller.
    • Metals are located in the bottom left of the periodic table.
    • Reactivity of metals increases down a group due to a greater atomic radius, which leads to a weaker attraction between outermost electrons and the nucleus.
    • A weaker attraction means less energy is required to remove the outermost electron to initiate chemical bonding or a reaction.

    Element Notation

    • Atomic number (Z) = number of protons = number of electrons.
    • Mass number (A) = number of nucleons = number of protons + number of neutrons.

    Properties of Metals, Nonmetals, and Semimetals

    • Metals: solid at room temperature (exception: mercury), malleable, ductile, good conductor of heat and electricity, lustrous, high density, high boiling and melting points.
    • Nonmetals: can be a gas, liquid, or solid (mostly gases), high ionisation, high electronegativity, poor thermal conductors, poor electrical conductors, little or no metallic lustre, low melting and boiling points.
    • Semimetals: form solid at room temperature, malleable, ductile, average thermal conductivity, semi-conductive, brittle.

    Drivers of Reactions

    • The rate of reaction is the speed at which a chemical reaction occurs.
    • Collision Theory: a chemical reaction can only occur if reacting particles collide at the correct orientation with sufficient energy (activation energy).
    • The kinetic theory of matter: all matter is composed of particles that are in constant motion.

    Factors Affecting the Rate of Reaction

    • Temperature: increases kinetic energy, particles move faster, increasing the frequency of collisions, and thus the rate of reaction.
    • (Note: other factors, such as concentration, surface area, and catalysts, can also affect the rate of reaction.)

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    Description

    Identify the contributions of famous scientists to the development of the periodic table, including Johann Dobereiner, John Newlands, Dmitri Mendeleev, Henry Moseley, and Antonine Lavoisier. Test your knowledge of their discoveries and how they shaped our understanding of the elements.

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