Atoms and Molecules
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Questions and Answers

What is the ratio of hydrogen to oxygen atoms in a water molecule?

  • 2:2
  • 1:1
  • 2:1 (correct)
  • 1:2

    • Helium is a diatomic element.

    False

    What is a negatively charged ion called?

    anion

    A molecule of water is made up of two hydrogen atoms and one ____ atom.

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

    Match the following particles with their charges:

    <p>Anion = Negatively charged Cation = Positively charged Sodium ion (Na+) = Cation Chloride ion (Cl-) = Anion</p> Signup and view all the answers

    Which of the following is a polyatomic element?

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

    Sodium chloride (NaCl) consists of only negatively charged ions.

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

    What type of molecules are formed by atoms of different elements joining together in definite proportions?

    <p>molecules of compounds</p> Signup and view all the answers

    What does the law of conservation of mass state?

    <p>Mass can neither be created nor destroyed.</p> Signup and view all the answers

    Lavoisier is known for establishing the law of constant proportions.

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

    Who presented the atomic theory in 1808?

    <p>John Dalton</p> Signup and view all the answers

    The law of constant proportions states that a compound is composed of elements in _____ proportions.

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

    Match the chemists with their contributions:

    <p>Antoine Lavoisier = Law of conservation of mass John Dalton = Atomic theory Joseph Proust = Law of constant proportions Robert Boyle = Experimental method in chemistry</p> Signup and view all the answers

    What is a fundamental concept of Dalton's atomic theory?

    <p>All matter is composed of atoms.</p> Signup and view all the answers

    According to Dalton, compounds are composed of only one type of atom.

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

    What should be done to prevent the contents of the flask from escaping during a reaction?

    <p>Put a cork on the mouth of the flask</p> Signup and view all the answers

    Who postulated the idea of indivisible particles called 'Parmanu'?

    <p>Maharishi Kanad</p> Signup and view all the answers

    Lavoisier conducted his research in the era of ancient Indian philosophers.

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

    What is the meaning of the term 'atom' as introduced by Democritus?

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

    The ____________ law states that mass is conserved in a chemical reaction.

    <p>law of conservation of mass</p> Signup and view all the answers

    Match the philosophers with their contributions:

    <p>Maharishi Kanad = Proposed the smallest particles 'Parmanu' Pakudha Katyayama = Elaborated on Kanad's doctrine Democritus = Introduced the concept of 'atom' Joseph L. Proust = Worked on experimental validations</p> Signup and view all the answers

    What did Pakudha Katyayama elaborate on?

    <p>The doctrine of combined form of particles</p> Signup and view all the answers

    Maharishi Kanad suggested that dividing matter would eventually lead to particles that could be divided further.

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

    Name one pair of substances listed under X and Y that can be prepared as a 5% solution.

    <p>copper sulphate and sodium carbonate</p> Signup and view all the answers

    What is the formula for sodium sulphate created by criss-crossing the valencies of ions?

    <p>Na2SO4</p> Signup and view all the answers

    A sodium ion has a valency of +1.

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

    What is the formula for sodium phosphate?

    <p>Na3PO4</p> Signup and view all the answers

    The formula for sodium sulphate is Na2______.

    <p>SO4</p> Signup and view all the answers

    Match the following ions with their valencies:

    <p>Na+ = +1 SO4^2- = -2 PO4^3- = -3 Cl- = -1</p> Signup and view all the answers

    What is the symbol for the ammonium ion?

    <p>NH4+</p> Signup and view all the answers

    Potassium ion has a valency of 2.

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

    What is the formula for calcium oxide?

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

    The symbol for iron (III) ion is ______.

    <p>Fe3+</p> Signup and view all the answers

    Match the following elements with their respective symbols:

    <p>Sodium = Na+ Magnesium = Mg2+ Zinc = Zn2+ Copper (II) = Cu2+</p> Signup and view all the answers

    Which of the following compounds is formed with a metal and a non-metal?

    <p>Calcium Chloride</p> Signup and view all the answers

    Magnesium ion is represented as Mg2-.

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

    What charge do phosphate ions carry?

    <p>3-</p> Signup and view all the answers

    What defines a molecule?

    <p>The smallest particle of an element or compound capable of independent existence</p> Signup and view all the answers

    Polyatomic ions can exist independently and do not carry any charge.

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

    What is the chemical formula of magnesium chloride?

    <p>MgCl2</p> Signup and view all the answers

    A sample containing 0.144 g of oxygen and 0.096 g of boron has a total mass of ______ g.

    <p>0.24</p> Signup and view all the answers

    Which of the following represents the main factor in determining the chemical formula of a molecular compound?

    <p>Valency of each element</p> Signup and view all the answers

    Match the following compounds with their chemical formulae:

    <p>Quick lime = CaO Hydrogen bromide = HBr Baking powder = NaHCO3 Potassium sulphate = K2SO4</p> Signup and view all the answers

    Calculate the molar mass of ethyne, C2H2.

    <p>26 g/mol</p> Signup and view all the answers

    Ionic compounds are formed by the sharing of electrons between atoms.

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

    Study Notes

    Ancient Indian and Greek Philosophers

    • Philosophers questioned the nature of matter and its divisibility
    • Indian philosopher Kanad proposed that matter could be divided into smaller and smaller particles (parmanu) until indivisible particles were reached
    • Greek philosophers Democritus and Leucippus suggested atoms (indivisible particles)

    Law of Conservation of Mass

    • Lavoisier and Proust's experiments led to the law
    • Mass is neither created nor destroyed in a chemical reaction

    Law of Constant Proportions

    • The ratio of masses of elements in a compound is constant
    • This ratio is independent of the source or method of preparation

    Dalton's Atomic Theory

    • All matter is composed of atoms
    • Atoms are indivisible and indestructible
    • Atoms of the same element are identical in mass and properties
    • Atoms combine in whole number ratios to form compounds
    • Relative atomic mass was defined using the ratios determined in chemical reactions

    Atomic Symbols

    • The first letter of a symbol is always uppercase
    • The second letter of a symbol, if any, is lowercase
    • Symbols are derived from the name of the element, sometimes from the color, or Greek, Latin or German name

    Atomic Mass

    • The relative atomic mass is the mass of an atom relative to 1/12th the mass of a carbon-12 atom

    Molecules

    • Molecules are groups of two or more atoms chemically bonded together
    • They represent the smallest particle of an element or compound capable of independent existence
    • Molecule can be composed the same atom type or different atom types

    Molecular Mass

    • The molecular mass is determined by adding the atomic masses of all atoms in a molecule

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    Atoms and Molecules PDF

    Description

    Explore the foundations of atomic theory in this quiz covering ancient Indian and Greek philosophies, the law of conservation of mass, the law of constant proportions, and Dalton's atomic theory. Test your knowledge on the contributions of philosophers like Kanad, Lavoisier, and Proust.

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