Chap 02 Part 1- Elements compounds
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Questions and Answers

Which of the following is the symbol for Potassium?

  • P
  • Ca
  • K (correct)
  • Na

    • What is the correct symbol for Beryllium?

  • Be (correct)
  • Bi
  • Br
  • B

    • Identify the element that has the symbol 'Ne'.

  • Nitrogen
  • Boron
  • Neon (correct)
  • Sulphur

    • Which element's symbol is 'Cl'?

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

    What is the symbol for Oxygen?

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

    Which of the following is a characteristic of non-metals?

    <p>They are soft solids or gases.</p> Signup and view all the answers

    What defines metalloids?

    <p>Elements with intermediate properties between metals and non-metals.</p> Signup and view all the answers

    Which of these elements is classified as a noble gas?

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

    Which symbol correctly represents Aluminium?

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

    Which of the following statements about the symbols of elements is true?

    <p>Most symbols correspond to the first one or two letters of their names.</p> Signup and view all the answers

    Which of the following is NOT a characteristic of non-metals?

    <p>They are excellent conductors of electricity.</p> Signup and view all the answers

    What is the primary reason for using two-letter symbols for elements with the same first letter?

    <p>To ensure uniqueness among elemental symbols.</p> Signup and view all the answers

    Which of the following elements has a symbol derived from its Latin name?

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

    What information does the symbol of an element convey?

    <p>The unique name of the element and one atom of it.</p> Signup and view all the answers

    How many elements are typically expected to be represented in a compound?

    <p>At least two elements.</p> Signup and view all the answers

    Which of these compounds is correctly defined based on its elemental composition?

    <p>Water is made up of hydrogen and oxygen.</p> Signup and view all the answers

    What does the symbol 'Na' represent in the context of elements?

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

    What distinguishes pure substances from mixtures?

    <p>Pure substances consist of particles of only one kind.</p> Signup and view all the answers

    What major contribution to chemistry did Jons Jacob Berzelius make?

    <p>Devised the system of chemical symbols</p> Signup and view all the answers

    Which of the following statements about elements is correct?

    <p>Elements can exist independently or combine with other elements.</p> Signup and view all the answers

    Which of these elements is classified as a metal?

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

    Which of the following elements was NOT discovered by Berzelius?

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

    During which century did Jons Jacob Berzelius make his contributions to chemistry?

    <p>19th century</p> Signup and view all the answers

    Which property is characteristic of metals?

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

    How many known elements are there today?

    <p>118</p> Signup and view all the answers

    What was one of Berzelius's achievements related to atomic weights?

    <p>He determined the atomic weights of nearly all known elements.</p> Signup and view all the answers

    What is the classification of the element with the symbol 'Au'?

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

    Which of the following statements is true about Jons Jacob Berzelius?

    <p>He is one of the founders of modern chemistry.</p> Signup and view all the answers

    What uniquely characterizes the composition of a compound?

    <p>It is always made up of the same elements in a fixed ratio.</p> Signup and view all the answers

    Which of the following properties is true for all compounds?

    <p>Compounds have different properties than their constituent elements.</p> Signup and view all the answers

    Which example correctly identifies the physical state of a compound at room temperature?

    <p>Sodium chloride is a solid.</p> Signup and view all the answers

    What is required to separate a compound into its constituent elements?

    <p>Chemical processes.</p> Signup and view all the answers

    What typically occurs during the formation of a compound?

    <p>Energy is released or absorbed.</p> Signup and view all the answers

    How do the properties of compounds differ from those of elements?

    <p>Compounds possess unique properties not found in their elements.</p> Signup and view all the answers

    What distinguishes a compound from an element?

    <p>A compound has different properties than its constituent elements.</p> Signup and view all the answers

    Which of the following classifications does not describe elements?

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

    Which property is true for noble gases?

    <p>They do not react chemically with other elements.</p> Signup and view all the answers

    What defines an element?

    <p>It is composed of only one kind of atom.</p> Signup and view all the answers

    What indicates that sodium chloride is a compound?

    <p>It can be broken down into sodium and chlorine.</p> Signup and view all the answers

    Which of the following is a characteristic of non-metals?

    <p>They are typically dull and poor conductors of heat.</p> Signup and view all the answers

    Which statement is true about elements?

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

    How can a compound be defined in terms of composition?

    <p>It is formed by the chemical combination of two or more elements.</p> Signup and view all the answers

    A pure substance consists of particles of only one ______.

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

    An ______ is a pure substance that cannot be broken down into simpler substances by any physical or ordinary chemical means.

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

    A ______ is a substance made up of two or more elements chemically combined together in a fixed ratio.

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

    The ______of an element is a single-letter or two-letter abbreviation of its full name.

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

    A ______ formula represents the composition of a molecule of an element or a compound.

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

    Study Notes

    Elements

    • Hydrogen, helium, lithium, beryllium, boron, carbon, nitrogen, oxygen, fluorine, neon, sodium, magnesium, aluminium, silicon, phosphorus, sulphur, chlorine, argon, potassium, and calcium are the first twenty elements.
    • There are 118 known elements today, out of which 92 occur naturally and the remaining are made by humans.

    Classification of Elements

    • Elements are classified into:
      • Metals: gold, silver, iron, aluminium, and copper are examples of metals.
        • They are usually hard solids.
        • They have a characteristic shine or lustre.
        • They are good conductors of heat and electricity.
        • They have high melting and boiling points.
      • Non-metals: carbon, hydrogen, oxygen, and nitrogen are examples of non-metals.
        • They are either soft solids or gases.
        • They do not possess shine or lustre.
        • They are bad conductors of heat and electricity.
        • They have low melting and boiling points.
      • Metalloids: silicon, germanium, arsenic, and antimony are examples of metalloids.
        • They have intermediate properties between those of metals and non-metals.
      • Noble or Inert Gases: helium, neon, argon, krypton, xenon, and radon are examples of noble or inert gases.
        • They do not react chemically with other elements.

    Symbols of Elements

    • Elements are represented by symbols, which are single-letter or two-letter abbreviations of their full names.
    • The present system of allotting symbols to the elements was introduced by J.J. Berzelius.
    • The IUPAC approves the names and symbols of new elements.

    Compounds

    • A compound is a substance made up of two or more elements chemically combined in a fixed ratio.
    • Compounds have properties different from those of their constituent elements.
    • Examples of compounds include water, sodium chloride (common salt), and sodium hydroxide.

    Characteristics of Compounds

    • Compounds are made up of two or more elements.
    • Compounds are homogeneous, meaning all samples of a compound are identical in composition and have the same properties throughout.
    • The properties of a compound are different from those of its constituent elements.
    • It is not possible to separate the constituents of a compound by physical means.
    • Energy is usually given off or absorbed when a compound is formed.

    Difference Between Elements and Compounds

    • Elements are made up of only one kind of substance.
    • Elements cannot be broken down into simpler substances by chemical means.
    • Elements have unique properties.
    • Compounds are made up of two or more elements.
    • Compounds can be broken down into their constituent elements by chemical means.
    • The properties of a compound are different from those of its constituent elements.

    Characteristics of Pure Substances

    • A pure substance consists of particles of only one kind.

    Classification of Elements

    • Elements are classified into four categories based on their properties: metals, non-metals, metalloids, and noble or inert gases.

    Definition of an Element

    • An element is a pure substance that cannot be broken down into simpler substances by any physical or ordinary chemical means.

    Symbol of an Element

    • An element's symbol is a single-letter or two-letter abbreviation of its full name.

    Definition of a Compound

    • A compound is a substance made up of two or more elements chemically combined together in a fixed ratio.

    Atomic Structure

    • An atom is the smallest particle of an element that possesses all the properties of that element.
    • Atoms may or may not have independent existence.

    Molecular Structure

    • A molecule is the smallest particle of an element or a compound that has independent existence.
    • Molecules show all the properties of the substance they represent.

    Molecular Formula

    • A molecular formula represents the composition of a molecule of an element or a compound.

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    Learn the names and symbols of the first 20 elements in the periodic table, from Hydrogen to Calcium. Test your knowledge of the chemical symbols and their corresponding elements.

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