Ions and Ionic Compounds
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Questions and Answers

What forms a cation?

  • A negatively charged ion that loses protons
  • A neutral atom that loses electrons (correct)
  • An atom that gains protons
  • An atom that gains neutrons

    • What is a characteristic property of ionic compounds in their solid state?

  • They are typically fluid and flexible
  • They have a high melting point (correct)
  • They are composed of both metals and gases
  • They are excellent conductors of electricity

    • What happens to the electrical conductivity of ionic compounds when they dissolve in water?

  • It remains unchanged
  • It becomes excellent (correct)
  • It depends on the solvent's temperature
  • It decreases significantly

    • What type of bond holds ionic compounds together?

    <p>Ionic bonds</p> Signup and view all the answers

    What describes the state of ionic solids?

    <p>They are rigid and brittle</p> Signup and view all the answers

    Which of the following elements typically forms cations?

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

    How does sodium chloride differ from its constituent elements, sodium and chlorine?

    <p>Sodium chloride is non-toxic while sodium and chlorine are dangerous</p> Signup and view all the answers

    Which of the following statements about binary ionic compounds is true?

    <p>They contain both a metal cation and a nonmetal anion</p> Signup and view all the answers

    What characterizes the valence shells of nonmetal atoms?

    <p>They readily gain electrons to fill their shells.</p> Signup and view all the answers

    What must the total number of positive and negative charges in an ionic compound be?

    <p>Identical.</p> Signup and view all the answers

    Which of the following correctly describes the formula of an ionic compound?

    <p>It indicates the simplest ratio of ions necessary for neutrality.</p> Signup and view all the answers

    Why is sodium chloride not referred to as a molecule?

    <p>It does not have discrete ion pairs.</p> Signup and view all the answers

    What happens to a main group element when it forms a cation?

    <p>It loses all its valence electrons.</p> Signup and view all the answers

    Which statement accurately describes the formation of cations for groups 13-17?

    <p>Cation charge equals group number minus 10.</p> Signup and view all the answers

    What defines the inert pair effect in heavy group elements?

    <p>Relatively low energy of the valence s-electron pair.</p> Signup and view all the answers

    What is typical for transition metals when they form cations?

    <p>They lose d electrons before s electrons.</p> Signup and view all the answers

    How does the electron configuration of the Ca2+ ion compare to that of its neutral atom?

    <p>It has the same electron configuration as Ar.</p> Signup and view all the answers

    What energy is required to dissociate one mole of NaCl into gaseous ions?

    <p>769 kJ</p> Signup and view all the answers

    What is the expected ion configuration for chromium when it loses electrons?

    <p>Loses its 4s electrons followed by its 3d electrons.</p> Signup and view all the answers

    Which trace element forms a Cr3+ ion?

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

    What happens to the electron configuration of an atom that forms an Al3+ ion?

    <p>It loses three valence electrons.</p> Signup and view all the answers

    What is the general trend for electron loss in transition metals?

    <p>They lose d electrons before s electrons irrespective of charge.</p> Signup and view all the answers

    Why do nonmetals have high electron affinities?

    <p>They readily accept electrons to achieve stable configurations.</p> Signup and view all the answers

    Study Notes

    Ions and Ionic Compounds

    • Ions are atoms or molecules with an electrical charge.
    • Cations are positive ions formed when atoms lose valence electrons.
    • Anions are negative ions formed when atoms gain valence electrons.
    • Ionic compounds (salts) are compounds composed of ions held together by ionic bonds (electrostatic attraction between oppositely charged ions).
    • Ionic compounds are typically solid, rigid, and brittle with high melting and boiling points, indicating strong ionic bonds.
    • Solid ionic compounds are poor conductors of electricity due to the fixed positions of ions. They become good conductors when melted or dissolved in water, allowing ions to move freely.
    • Sodium atoms (Na) react explosively with water, while chlorine gas (Cl2) is corrosive and poisonous; however, sodium chloride (NaCl) is essential for life and readily dissolves in water.

    Properties of Ionic Compounds

    • Ionic compounds have different properties compared to their constituent elements due to the formation of ionic bonds.
    • Binary ionic compounds are composed of a metal (cation) and a nonmetal (anion).
    • The total positive charge of cations must equal the total negative charge of anions in an ionic compound (electrical neutrality).
    • The formula of an ionic compound represents the simplest ratio of ions needed for electrical neutrality. For example, Al2O3 has two Al3+ cations and three O2- anions.
    • The formula doesn't show physical arrangement. Ionic bonds are isotropic, attracting ions in all directions, forming a three-dimensional lattice structure, like in NaCl.

    Formation of Ionic Compounds

    • Metals tend to lose electrons easily (low ionization potential), and nonmetals readily gain electrons (high electron affinity).
    • Ionic compound formation is governed by periodic properties, with metals typically positioned on the left and nonmetals on the right of the periodic table.
    • The energy required to dissociate one mole of an ionic solid into gaseous ions is characteristic of the strength of its ionic bonds expressed in kJ/mole.
    • For NaCl, this is 769 kJ/mol.

    Electronic Structures of Cations

    • Main group elements form cations by losing valence electrons, achieving the noble gas electron configuration of the element that precedes it in the periodic table.
    • For groups 1 and 2, the charge of the cation is equal to the group number.
    • For groups 13-17, the cation charge is equal to the group number minus 10. For example, Al (group 13) forms Al3+
    • Exceptions exist, particularly among heavier elements, due to the "inert pair effect" where valence "s" electrons are less readily lost.
    • Transition metals lose outermost "s" electrons first, often followed by "d" electrons, leading to various cation charges (e.g., Fe2+ and Fe3+)
    • Inner transition metals typically form 3+ cations.

    Determining Electronic Structures of Cations

    • "Essential trace elements" are required by the human body in small amounts as ions for various bodily functions.
    • The electron configurations of ions are derived from the neutral atom's configuration, adjusting for the addition or removal of electrons from energy orbitals.

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    Description

    This quiz covers the fundamental concepts of ions and ionic compounds. It explores the formation of cations and anions, the properties of ionic compounds, and their behavior in different states. Test your understanding of these essential chemistry topics!

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