Grade 6 Chemistry Ch. 3 Quiz(elements)
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Questions and Answers

What is an element?

  • A pure substance made of one kind of atom (correct)
  • A mixture of different types of particles
  • A collection of atoms with variable properties
  • A compound formed by chemical bonds

    • An impure substance contains a mixture of two or more types of particles.

    True

    What is the smallest particle of an element called?

    atom

    The center of an atom is called the ______.

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

    Which of the following sub-atomic particles has a positive charge?

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

    Match the sub-atomic particles with their charges:

    <p>Proton = Positive charge Electron = Negative charge Neutron = No charge Nucleus = Contains protons and neutrons</p> Signup and view all the answers

    Electrons revolve around the nucleus in defined paths known as shells.

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

    A pure substance has _________ composition throughout.

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

    Which of the following is NOT a noble gas?

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

    All non-metals are brittle.

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

    Name an example of a metalloid.

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

    The symbol for Iron is ____.

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

    Match the following elements with their classification:

    <p>Helium = Noble gas Boron = Metalloid Iron = Metal Graphite = Non-metal</p> Signup and view all the answers

    Which property is characteristic of metals?

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

    All metals are solid at room temperature.

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

    What is a common use of noble gases?

    <p>Lighting or gas discharge tubes</p> Signup and view all the answers

    ____ and Neon are examples of noble gases.

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

    Match the following non-metal characteristics with their definitions:

    <p>Not malleable = Cannot be shaped into sheets Does not have lustre = Lacks shiny appearance Bad conductor = Poor in conducting electricity Does not make resonating sound = Not sonorous</p> Signup and view all the answers

    Which compound has the formula H2O?

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

    Compounds can be separated into their constituent elements by physical methods.

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

    What is the molecular formula of sulphuric acid?

    <p>H2SO4</p> Signup and view all the answers

    The compound NaCl is commonly known as ______.

    <p>sodium chloride</p> Signup and view all the answers

    Match the following compounds with their formulas:

    <p>Carbon dioxide = CO2 Sodium chloride = NaCl Nitric acid = HNO3 Magnesium oxide = MgO</p> Signup and view all the answers

    What is the symbol for Tungsten?

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

    The atomicity of most metals is two.

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

    What term describes the number of atoms that constitute a molecule?

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

    Elements are made of only one kind of __________.

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

    Which of the following molecules has an atomicity of 4?

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

    Chlorine is a diatomic molecule.

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

    Provide an example of a molecule of an element.

    <p>H₂</p> Signup and view all the answers

    The molecular formula for oxygen is __________.

    <p>O₂</p> Signup and view all the answers

    Match the following elements with their atomicity:

    <p>Hydrogen = 2 Ozone = 3 Sulphur = 8 Phosphorus = 4</p> Signup and view all the answers

    Which of the following statements about elements is correct?

    <p>Elements consist of only one kind of atom.</p> Signup and view all the answers

    Study Notes

    Elements

    • An element is a pure substance composed of one kind of atom, unable to be broken down into simpler substances.
    • Pure substances have uniform composition and defined properties; impure substances contain mixed particles and lack definite composition.
    • Atoms are the smallest units of elements, examples include oxygen (O), hydrogen (H), nitrogen (N), and sulfur (S).

    Structure of Atom

    • The nucleus at the atom's core contains:
      • Protons (+): Positively charged particles.
      • Neutrons: Neutral particles with no charge.
    • Electrons (-): Negatively charged particles, orbiting around the nucleus in shells.

    Classification of Elements

    • Elements are categorized as metals, non-metals, metalloids, and noble gases.
    • Metalloids display properties of both metals and non-metals (e.g., Boron, Silicon, Germanium).
    • Noble gases are inert and found in trace amounts in the air (e.g., Helium, Neon, Argon).

    Metals vs. Non-Metals

    • Metals possess lustre, are typically hard (except sodium and mercury), malleable, ductile, sonorous, and good conductors of heat and electricity.
    • Non-metals lack lustre, are brittle, not malleable or ductile, do not resonate, and are poor conductors of heat and electricity (except graphite).

    Element Names and Symbols

    • Some element symbols are derived from Latin names:
      • Iron: Ferrum (Fe)
      • Tungsten: Wolfram (W)

    Molecules

    • A molecule represents the smallest particle of a substance that can exist independently.
    • Molecules form from:
      • The combination of the same elements (e.g., O2, H2).
      • Different elements (e.g., HCl, H2O).

    Atomicity

    • Atomicity indicates the number of atoms in a molecule.
    • Most metals and noble gases have an atomicity of one (monoatomic).
    • Common molecular formulas and their atomicity include:
      • Hydrogen (H2): atomicity 2
      • Ozone (O3): atomicity 3
      • Phosphorus (P4): atomicity 4

    Compounds

    • A compound is a pure substance formed from two or more different elements combined chemically in a fixed ratio.
    • Examples of common compounds and their formulas:
      • Water: H2O
      • Ammonia: NH3
      • Sodium Chloride: NaCl

    Characteristics of Compounds

    • Elements in a compound are chemically bonded in a specific ratio (e.g., water consists of two hydrogen atoms for every oxygen atom).
    • Compounds exhibit unique properties distinct from their constituent elements.
    • Elements within a compound cannot be separated by physical methods; separation often requires chemical reactions (e.g., electrolysis for water).

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    Description

    Test your understanding of elements, compounds, and mixtures in this Grade 6 Chemistry Chapter 3 quiz. Discover key concepts and definitions about pure and impure substances. Challenge yourself and enhance your chemistry knowledge!

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