Chemistry: Properties and Changes of Matter
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Questions and Answers

What is the main difference between physical and chemical change?

  • Physical change changes the state of matter, whereas chemical change changes the composition of matter. (correct)
  • Chemical change changes the color of matter, whereas physical change changes the composition of matter.
  • Physical change changes the color of matter, whereas chemical change changes the state of matter.
  • Chemical change changes the state of matter, whereas physical change changes the composition of matter.

    • What is the difference between a molecule and a compound?

  • A molecule is a pure substance, while a compound is a mixture.
  • A compound is made up of two or more atoms of the same element, while a molecule is made up of two or more atoms of different elements.
  • A molecule is made up of two or more atoms of the same element, while a compound is made up of two or more atoms of different elements. (correct)
  • A compound is a pure substance, while a molecule is a mixture.

    • Which of the following scientists proposed the first atomic theory based on experimental evidence?

  • Empedocles
  • Aristotle
  • John Dalton (correct)
  • Democritus

    • What is the main difference between the atomic theories of Democritus and Dalton?

    <p>Dalton's theory was based on experimental evidence while Democritus' was based on philosophical reasoning. (D)</p> Signup and view all the answers

    Which of the following statements best summarizes Mendeleev's contribution to the periodic table?

    <p>He arranged the elements by atomic mass, leaving gaps for undiscovered elements and predicting their properties. (B)</p> Signup and view all the answers

    Which of the following elements exists as a diatomic molecule?

    <p>Oxygen (O) (D)</p> Signup and view all the answers

    What is the main difference between Newlands' and Mendeleev's periodic tables?

    <p>Newlands' table did not leave any gaps for undiscovered elements, while Mendeleev's did. (C)</p> Signup and view all the answers

    Which of these is NOT a characteristic of a chemical change?

    <p>Change in state. (C)</p> Signup and view all the answers

    Which of Dalton's postulates was proven incorrect by the discovery of isotopes?

    <p>All atoms of the same element are identical in size, mass, and chemical and physical composition. (D)</p> Signup and view all the answers

    What experimental setup was crucial for the discovery of the electron?

    <p>Cathode ray tube (B)</p> Signup and view all the answers

    Which of the following statements accurately describes Rutherford's model of the atom?

    <p>A dense, positively charged nucleus surrounded by a cloud of negatively charged electrons. (B)</p> Signup and view all the answers

    What did the results of Rutherford's gold foil experiment reveal about the structure of the atom?

    <p>Atoms are mostly empty space with a small, dense nucleus. (C)</p> Signup and view all the answers

    Which scientist is credited with discovering the neutron?

    <p>James Chadwick (C)</p> Signup and view all the answers

    Which of the following is NOT a fundamental postulate of Dalton's atomic theory?

    <p>Atoms are composed of protons, neutrons, and electrons. (B)</p> Signup and view all the answers

    What property of cathode rays convinced J.J. Thomson that they were composed of particles?

    <p>They can be bent by a magnetic field. (C)</p> Signup and view all the answers

    What evidence did Rutherford's gold foil experiment provide to support the nuclear model of the atom?

    <p>All of the above. (D)</p> Signup and view all the answers

    Flashcards

    Physical Property

    A characteristic of a substance that describes its attributes like taste, color, or state.

    Chemical Property

    Reactive characteristics of a substance that change it into a new substance.

    Physical Change

    A change in matter that does not alter its identity or composition.

    Chemical Change

    A change in matter that results in the formation of a new substance.

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    Mendeleev

    Created the periodic table based on atomic mass and predicted properties of undiscovered elements.

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    Dalton

    Revitalized atomic theory based on experimental evidence, differing from earlier philosophers.

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    Atoms

    The smallest unit of matter, indivisible as proposed by Democritus.

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    Diatomic Elements

    Elements that exist as two atoms covalently bonded together, like H2 or N2.

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    Atom indivisibility

    Atoms cannot be subdivided into smaller particles.

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    Conservation of atoms

    Atoms cannot be created or destroyed in a chemical reaction.

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    Identical atoms

    All atoms of the same element are identical in size and mass.

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    Element properties

    Atoms of different elements have distinct properties.

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    Atomic ratios

    Atoms combine in small, whole number ratios to form compounds.

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    Cathode ray tube

    Device that enabled the study of subatomic particles like electrons.

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    Rutherford's gold foil experiment

    Showed that atoms are mostly empty space with a dense nucleus.

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    Discovery of neutrons

    Chadwick found that atomic nuclei contain neutral particles called neutrons.

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    Study Notes

    Physical Properties

    • A characteristic of a substance
    • Describes how a substance appears (taste, texture, color)
    • Describes a substance's state and changes in state
    • Examples of physical properties include taste, texture, color, and state changes

    Physical Changes

    • A change in matter that does not alter the substance's identity
    • Examples include breaking, dissolving, melting, boiling, and freezing

    Chemical Properties

    • The reactive characteristics of a substance
    • Describes how a substance changes into a new substance
    • Examples include the reaction of calcium with water and burning paper

    Chemical Changes

    • A change in matter that alters a substance's identity
    • A new substance is formed during a chemical change
    • Examples include burning wood, rusting of iron and the reaction of vinegar with baking soda

    Elements

    • Pure substances that contain only one type of atom
    • Found on the periodic table
    • Atomic examples include sodium (Na), copper (Cu), lithium (Li), and iron (Fe)
    • Diatomic elements: Exist as two atoms covalently bonded together (e.g., H₂, Br₂, N₂)
    • Example diatomic elements: "HOBrFINCI"

    Molecules

    • Consist of two or more atoms bonded together
    • Examples include water (H₂O), glucose (C₆H₁₂O₆), and fluorine (F₂)

    Compounds

    • Molecules containing more than one type of element

    The Periodic Table

    • A tabular arrangement of chemical elements
    • History included in the slides

    Dobereiner (1829)

    • Developed the concept of "triads"
    • Noted that groups of three elements share similar chemical behaviors
    • Did not work for all elements

    Newlands (1864)

    • Organized elements by atomic weight
    • Noted that every eighth element had similar properties (Law of Octaves)
    • Gaps in the table were not accounted for

    Mendeleev (1869)

    • Organized elements by atomic weight (and properties)
    • Created the Periodic Table as we know it today
    • Prediction of undiscovered elements and their properties
    • Issues existed with the ordering of elements based on weights

    Moseley (1913)

    • Arranged the periodic table by atomic number
    • Atomic number was more suitable for arranging the elements than atomic mass

    History of the Atom

    • Ancient Greek philosophers, including Democritus, proposed the concept of atoms as indivisible particles

    Democritus (~460 - ~370 BCE)

    • Proposed the atomic theory
    • First to propose the theory
    • Coined the term "atom," meaning indivisible
    • No experimental evidence

    Aristotle (384-322 BCE)

    • Criticized Democritus' theory
    • Supported the four-element theory proposed by Empedocles (Earth, Air, Water, Fire).
      • This theory held for nearly 2,000 years later

    John Dalton (1766-1844)

    • Revitalized atomic theory from the basis of experimental evidence
    • Scientist and teacher
    • His theories were different from those of Greek philosophers

    Dalton's Atomic Theories

    • Atoms cannot be subdivided / created / destroyed.
    • All atoms of the same element are identical.
    • Atoms combine in small whole-number ratios to form compounds

    Thompson (1856-1940)

    • Discovered the electron
    • Proposed the "raisin bun model" of the atom
    • Electrons embedded in a positively charged sphere

    Ernest Rutherford (1871-1937)

    • Conducted the gold foil experiment
    • Discovered the nucleus of the atom
    • Demonstrated that most of an atom is empty space
    • Proved atom contained a densely packed positive core (nucleus)

    James Chadwick (1891-1974)

    • Discovered the neutron
    • Neutral particles in the atomic nucleus, along with protons.

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    Chemistry Basics: History & Properties (PDF)

    Description

    Explore the fundamental concepts of physical and chemical properties and changes in matter. This quiz covers characteristics such as taste, texture, state changes, and the transformation of substances. Test your understanding of elements and the periodic table with this engaging quiz.

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