Chemistry Basics: Atoms and Chemical Formulas
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Questions and Answers

Which branch of chemistry focuses on the study of living organisms?

  • Physical Chemistry
  • Biochemistry (correct)
  • Analytical Chemistry
  • Organic Chemistry

    • Inorganic Chemistry covers all chemical compounds that are organic.

    False

    What is the study of matter and the changes it undergoes known as?

    Chemistry

    _______ Chemistry applies physics to the study of chemistry.

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

    Match the following branches of chemistry with their descriptions:

    <p>Analytical Chemistry = Analysis of chemical substances Biochemistry = Study of living organisms Organic Chemistry = Primarily carbon and hydrogen compounds Inorganic Chemistry = Non-organic chemical compounds</p> Signup and view all the answers

    Which of the following is a binary acid?

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

    Phosphorous acid is represented by the formula H3PO4.

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

    What is the molar mass of HBr?

    <p>81 g/mol</p> Signup and view all the answers

    The percentage composition of oxygen in H2PO4 is _______.

    <p>65.98%</p> Signup and view all the answers

    Match the following acids with their characteristics:

    <p>HBr = Hydrobromic acid H3PO4 = Phosphoric acid HF = Hydrofluoric acid H3PO3 = Phosphorous acid</p> Signup and view all the answers

    What is the empirical formula for the compound analyzed?

    <p>MgCO3</p> Signup and view all the answers

    The ratio of moles of magnesium to moles of carbon is greater than 1.

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

    What is the mass of carbon in grams present in the compound?

    <p>14.24</p> Signup and view all the answers

    The percentage of oxygen in the compound is ___%.

    <p>56.93</p> Signup and view all the answers

    Match the element to its corresponding moles in the compound:

    <p>Mg = 1.20 C = 1.19 O = 3.56</p> Signup and view all the answers

    Which of the following particles has a positive charge?

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

    The atomic number is equal to the number of protons in an atom.

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

    What is the term for atoms of the same element that have different masses?

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

    The part of the atom where most of the atom's mass is found is called the ______.

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

    Match the following formulas with their types:

    <p>H₂O = Molecular Formula C₂H₅ = Empirical Formula Mg₃N₂ = Molecular Formula HO = Empirical Formula</p> Signup and view all the answers

    What does the oxidation number indicate?

    <p>The number of electrons an atom loses or gains</p> Signup and view all the answers

    A cation is negatively charged because it gains electrons.

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

    What is the formula for the compound formed by sodium and chlorine?

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

    In a chemical reaction, an anion is formed when an atom ______ electrons.

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

    Match the following ions with their charges:

    <p>Na+ = Cation Cl- = Anion Mg2+ = Cation PO43- = Anion</p> Signup and view all the answers

    What does the skeletal equation for the reaction of aluminum and sulfuric acid produce?

    <p>Hydrogen and aluminum sulfate</p> Signup and view all the answers

    In a synthesis reaction, two or more reactants form a single product.

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

    What type of reaction is represented by the equation $CaCO_3 \rightarrow CaO + CO_2$?

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

    In a double replacement reaction, the general form is AB + CD → ______ + ______.

    <p>AD, BC</p> Signup and view all the answers

    Match the following types of reactions with their general equations:

    <p>Synthesis = A + B → AB Decomposition = AB → A + B Single Replacement = A + BC → AC + B Double Replacement = AB + CD → AD + BC</p> Signup and view all the answers

    What is the empirical formula of diborane?

    <p>BH_3</p> Signup and view all the answers

    The molecular formula of diborane is B_2H_6.

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

    Calculate the molar mass of diborane (B_2H_6).

    <p>27.67 g/mol</p> Signup and view all the answers

    The multiplier used to determine the molecular formula from the empirical formula is __________.

    <p>2</p> Signup and view all the answers

    Match the following components with their respective values:

    <p>Molar mass of diborane = 27.67 g/mol Mass of boron in diborane = 12.89 g Mass of hydrogen in diborane = 3.606 g Empirical formula mass = 14 g/mol</p> Signup and view all the answers

    How many oxygen atoms are present in the products of the equation C2H4 + 3O2 → 2CO2 + 2H2O?

    <p>6</p> Signup and view all the answers

    The balanced equation BaCl2 + 2Na(OH)2 → Ba(OH)2 + 2NaCl contains 6 sodium atoms.

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

    What is the coefficient of NaCl in the balanced equation BaCl2 + 2Na(OH)2 → Ba(OH)2 + 2NaCl?

    <p>2</p> Signup and view all the answers

    In the reaction C2H4 + 3O2 → 2CO2 + 2H2O, the total number of carbon atoms in the reactants equals ___ in the products.

    <p>2</p> Signup and view all the answers

    Match the following elements with their quantities in the reactants of the equation C2H4 + 3O2:

    <p>C = 2 H = 4 O = 6</p> Signup and view all the answers

    What is the correct name for the compound NaF?

    <p>Sodium fluoride</p> Signup and view all the answers

    FeCl3 is also known as ferrous chloride.

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

    What is the traditional name for CuF2?

    <p>Cupric fluoride</p> Signup and view all the answers

    MgO is commonly known as __________.

    <p>magnesium oxide</p> Signup and view all the answers

    Match the following compounds with their traditional names:

    <p>FeCl2 = Ferric chloride FeCl3 = Ferrous chloride CuF = Cupric fluoride CuF2 = Cuprous fluoride</p> Signup and view all the answers

    Study Notes

    Atom

    • An atom is indivisible and the smallest unit of matter.
    • Subatomic particles include:
      • Proton (+) discovered by Ernest Rutherford.
      • Electron (−) discovered by Joseph John Thomson.
      • Neutron discovered by James Chadwick.
    • The nucleus contains most of the atom's mass, with atomic mass calculated as the sum of protons and neutrons.
    • The atomic number represents the number of protons, which equals the number of electrons in a neutral atom.
    • Isotopes are variants of the same element with differing masses.

    Chemical Formula

    Types

    • Empirical Formula represents the simplest ratio of elements.
      • Examples:
        • H₂O₂ simplifies to HO.
        • C₄H₁₀ simplifies to C₂H₅.
        • C₆H₁₂O₆ simplifies to CH₂O.
    • Molecular Formula shows the exact number of atoms.
      • Examples:
        • Mg₃N₂
        • Ca(OH)₂

    Branches of Chemistry

    • Analytical Chemistry: Focused on the analysis of substances.
    • Biochemistry: Studies chemical processes in living organisms.
    • Organic Chemistry: Deals primarily with carbon-containing compounds.
    • Inorganic Chemistry: Covers compounds that are not organic.
    • Physical Chemistry: Combines principles of physics with chemistry.

    Acids

    • Binary Acids contain hydrogen and examples include:
      • HBr (hydrobromic acid)
      • HF (hydrofluoric acid)
      • HI (hydroiodic acid)
    • Ternary Acids contain hydrogen and oxygen; examples include:
      • H₃PO₄ (phosphoric acid)
      • H₃PO₃ (phosphorous acid)

    Molar Mass

    • Molar mass is computed as the sum of atomic weights multiplied by their respective subscripts.
    • Example calculations:
      • For HBr:
        • H: 1 × 1 = 1
        • Br: 1 × 80 = 80
        • Total = 81 g/mol
      • For H₂PO₄:
        • H: 2 × 1 = 2
        • P: 1 × 31 = 31
        • O: 4 × 16 = 64
        • Total = 97 g/mol

    Percentage Composition

    • Percentage of each element can be determined using:
      • % of element = (number of atoms × atomic mass) / molar mass × 100

    Structural Formula

    • Represents the arrangement of atoms within molecules; examples include:
      • H₂O depicted as H-O-H
      • C₄H₁₀ depicted as H-C-C-C-C-H

    Atoms and Electrons

    • Atoms may gain or lose electrons, leading to oxidation states.
      • Cation: Positively charged (loses electrons).
      • Anion: Negatively charged (gains electrons).

    Example Compounds

    Cation Anion Compound
    Na⁺ Cl⁻ NaCl
    K⁺ NO₃⁻ KNO₃
    Mg²⁺ PO₄³⁻ Mg₃(PO₄)₂

    Chemical Applications

    • To determine empirical formulas from percentage composition, convert percentages to moles, find mole ratios, and derive the simplest formula.
      • Example compound with 28.82% Mg, 14.24% C, and 56.93% O results in empirical formula MgCO₃.

    Molecular Formula Example

    • For diborane:
      • Calculate grams of boron and hydrogen.
      • Find empirical formula BH₃.
      • Molar mass calculation leads to molecular formula B₂H₆.

    Chemical Equations

    • Basic format: Reactants → Products.
    • Example of word equation: Aluminum + Sulfuric acid → Hydrogen + Aluminum sulfate.
    • Example of skeletal equation: ( Al_{(s)} + H_2 SO_4 \longrightarrow H_2 + Al_2 (SO_4)_3 ).

    Types of Reactions

    • Synthesis: A + B → AB.
    • Decomposition: AB → A + B.
    • Single Replacement: A + BC → AC + B.
    • Double Replacement: AB + CD → AD + BC.

    Naming Compounds

    • Binary Ionic Compounds end in -ide (e.g., NaF - sodium fluoride).
    • Compounds with metals that have varying oxidation states use Stock or Traditional nomenclature (e.g., Iron (II) chloride, ferrous chloride).

    Balancing Chemical Equations

    • Ensure the number of each type of atom is the same on both sides of the equation.
    • Example:
      • ( BaCl_2 + 2Na(OH){2} → Ba(OH){2} + 2NaCl ) balances Ba, Cl, Na, O, and H.
      • ( C_2H_4 + 3O_2 → 2CO_2 + 2H_2O ) balances C, H, and O.

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    Description

    Explore the fundamentals of atoms and chemical formulas in this quiz. You'll learn about the subatomic particles, their contributions, and the various types of chemical formulas such as empirical formulas. Test your knowledge of atomic structure and chemical representation.

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