Chemistry: Atoms, Molecules, and Compounds
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Chemistry: Atoms, Molecules, and Compounds

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Questions and Answers

What happens to an atom when it gains electrons?

  • It becomes neutral.
  • It becomes negatively charged. (correct)
  • It loses its protons.
  • It becomes positively charged.

    • What is the molecular formula for common salt?

  • NaCl (correct)
  • Na2Cl
  • ClNa
  • KCl

    • Which statement is true about ions?

  • Ions have equal numbers of protons and electrons.
  • Ions can be either positively or negatively charged. (correct)
  • Ions do not participate in chemical reactions.
  • Ions are always neutral.

    • What scientific principle does Thales's experiment with amber demonstrate?

    <p>The concept of static electricity.</p> Signup and view all the answers

    What major concept did Benjamin Franklin contribute to the understanding of electricity?

    <p>The idea of electrical current as an energy transfer.</p> Signup and view all the answers

    When an atom is balanced, what characteristic does it exhibit?

    <p>It has an equal number of protons and electrons.</p> Signup and view all the answers

    What is the main difference between conductors and insulators?

    <p>Conductors allow the flow of electric current while insulators do not.</p> Signup and view all the answers

    What are the atoms that comprise water?

    <p>Hydrogen and Oxygen.</p> Signup and view all the answers

    In electrical terms, what does a positively charged ion indicate?

    <p>It has lost electrons.</p> Signup and view all the answers

    Which of the following elements is a good conductor of electricity?

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

    Which of the following materials is typically classified as a good electrical insulator?

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

    In the context of semi-conductors, what is the role of Boron when incorporated into the material?

    <p>It creates electron holes.</p> Signup and view all the answers

    What characteristic do Silicon and Germanium share that classifies them predominantly as semi-conductors?

    <p>They contain 4 electrons in their valence shell.</p> Signup and view all the answers

    What determines whether a semi-conductor material is classified as N-Type?

    <p>The addition of extra electrons through impurities.</p> Signup and view all the answers

    Which of the following is NOT a good insulator as per common classifications?

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

    Which statement accurately describes the bonding situation in a Boron atom?

    <p>It has no electrons available to form covalent bonds.</p> Signup and view all the answers

    What is the primary feature of the crystalline structure of semi-conductors like Silicon?

    <p>A defined arrangement of atoms that allows for controlled conductivity.</p> Signup and view all the answers

    What effect does adding impurities like Arsenic to a semiconductor have?

    <p>It reduces the material's overall resistance.</p> Signup and view all the answers

    What defines the general structure and behavior of insulators compared to conductors and semi-conductors?

    <p>Insulators have tightly bound electrons that do not conduct electricity.</p> Signup and view all the answers

    What is the primary function of outer or valence electrons in a material?

    <p>To facilitate the flow of electric current when moved</p> Signup and view all the answers

    Which characteristic defines a good conductor?

    <p>Loose hold on 1 to 3 electrons in the valence shell</p> Signup and view all the answers

    Why do insulators have a high resistivity?

    <p>Their electrons are tightly held and cannot move easily</p> Signup and view all the answers

    Which of the following metals is NOT considered a good conductor?

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

    What role do free electrons play in a conducting material?

    <p>They are responsible for the movement that constitutes electric current</p> Signup and view all the answers

    What occurs when a positive electrical force acts on valence electrons?

    <p>Electrons are forced from their orbit, creating a positively charged ion</p> Signup and view all the answers

    Which of the following best describes the electron configuration of a good insulator?

    <p>5 – 8 electrons tightly held in the valence shell</p> Signup and view all the answers

    Which statement is true about semi-conductors compared to conductors and insulators?

    <p>They possess properties of both conductors and insulators</p> Signup and view all the answers

    What is the effect of increasing temperature on the resistance of conductors?

    <p>It generally increases resistance</p> Signup and view all the answers

    What is the charge of neutrons in an atom?

    <p>Neutrally charged</p> Signup and view all the answers

    Which statement accurately describes molecules?

    <p>They are the smallest particles of a substance that retain its properties.</p> Signup and view all the answers

    In which of the following would you find a compound?

    <p>Pure water (H2O)</p> Signup and view all the answers

    The molecular structure of _____ consists of two or more atoms bonded together.

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

    Which type of particle is predominant in the structural makeup of conductors?

    <p>Electrons and protons</p> Signup and view all the answers

    What is true about electrical charges within conductors?

    <p>They can migrate freely allowing for conductivity.</p> Signup and view all the answers

    What defines a compound?

    <p>A substance made of identical molecules comprised of different atoms.</p> Signup and view all the answers

    Which of these best represents the structure of nicotine?

    <p>C10H14N2</p> Signup and view all the answers

    What role do protons play in an atom?

    <p>They balance the negative charge of electrons.</p> Signup and view all the answers

    Which of the following options is NOT a part of atomic structure?

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

    Study Notes

    Atoms

    • Atoms are the smallest particles to which elements can be reduced while retaining their characteristics.
    • Atoms are comprised of protons (positively charged), neutrons (neutrally charged), and electrons (negatively charged).
    • The forces between positive and negative charges are the fundamental cause of electrical phenomena.

    Molecules

    • Molecules are composed of two or more atoms bonded together.
    • They are the smallest particle of a substance that can be reduced while maintaining its characteristics.
    • This applies to all substances, including liquids, solids, and gases.
    • A molecule of Nicotine (C10H14N2) contains 10 Carbon atoms, 14 Hydrogen atoms, and 2 Nitrogen atoms.

    Compounds

    • Compounds are substances where all molecules are identical, but the molecules are comprised of different atoms in exact proportions.
    • These elements combine to form a separate substance with characteristics different from the original elements.
    • Examples include water (H2O), carbon dioxide (CO2), and common salt (NaCl).

    Ions

    • Normal atoms have a neutral charge due to an equal number of protons and electrons.
    • An ion is an atom that has lost or gained electrons.
    • Atoms with lost electrons have a positive charge, while atoms with gained electrons have a negative charge.

    Static Electricity

    • The Greek philosopher Thales experimented with static electricity around 500 BC.
    • Certain materials exert forces on each other, which were discovered to be electrical.
    • Rubbing amber strips it of electrons, making it positive and able to attract a negative substance.

    Benjamin Franklin

    • Benjamin Franklin experimented with wet string and a metal key in a thunderstorm.
    • He discovered that energy was transferred from lightning to the ground and was the first to use the term "current."
    • Energy transfer is now the major use for electricity.

    Conductors and Insulators

    • A balanced atom has an equal number of protons and electrons.
    • Electrostatic attraction holds electrons in orbit, opposing the centrifugal force.
    • The outermost electron shell is called the valence shell, and it contains the valence electrons.

    Conductors

    • Substances that readily permit the free flow of a large number of electrons are called conductors.
    • A good conductor has 1-3 valence electrons, which are more loosely held in orbit and have room for more electrons to join.
    • Four good conductors are silver, copper, gold, and aluminum.

    Insulators

    • Materials that inhibit the flow of electricity are called insulators.
    • A good insulator has 5-8 valence electrons, which are solidly held in orbit and do not readily move to another atom.
    • Insulators have a high resistivity.
    • Four good insulators are glass, rubber, plastic, and ceramic.

    Semi-conductors

    • Semi-conductors have 4 electrons in the valence shell.
    • Silicon and Germanium exist in this configuration, form a crystalline structure, and are almost insulators.
    • Mixing in impurities will produce a semi-conductor.
    • Arsenic incorporates extra electrons (N-type material), while Boron incorporates electron holes (P-type material).
    • Semi-conductors are the basis of electronic components.

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    Description

    This quiz explores the fundamental concepts of atoms, molecules, and compounds. Understand the structure of atoms, how molecules form from atoms, and the characteristics of compounds. Test your knowledge on the basic building blocks of matter!

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