Life and Chemistry: Small Molecules
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Questions and Answers

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

  • Isotopes (correct)
  • Atoms
  • Ions
  • Molecules

    • Which electron shell is closest to the nucleus and contains only one s orbital?

  • Second shell
  • First shell (correct)
  • Third shell
  • Fourth shell

    • How many electrons can occupy a single orbital?

  • Two (correct)
  • Three
  • Four
  • One

    • What happens when a radioactive isotope decays?

    <p>It loses energy and may lose a proton</p> Signup and view all the answers

    What is the maximum number of electrons the second shell can accommodate?

    <p>8</p> Signup and view all the answers

    Which of the following best describes the role of a radioactive isotope in medical applications?

    <p>It helps in diagnosing diseases</p> Signup and view all the answers

    Which of the following statements is true regarding atomic structure?

    <p>Atoms of an element always have the same number of protons.</p> Signup and view all the answers

    What determines how an atom reacts with other atoms?

    <p>The electrons found in the valence shell</p> Signup and view all the answers

    What is the maximum number of electrons that can be found in the second shell of an atom?

    <p>8 electrons</p> Signup and view all the answers

    Which element has a valence of four?

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

    What is the term for the number of unpaired valence electrons in an atom?

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

    Which of the following statements is true regarding the octet rule?

    <p>Hydrogen is not considered under the octet rule.</p> Signup and view all the answers

    What kind of bond involves the sharing of a pair of electrons between two atoms?

    <p>Covalent bond</p> Signup and view all the answers

    How many orbitals are there in the second shell of an atom?

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

    Which of the following elements does NOT typically follow the octet rule?

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

    What causes the repulsion between atomic nuclei?

    <p>Mutually repelling positive charges</p> Signup and view all the answers

    Which type of covalent bond results in the sharing of three pairs of electrons?

    <p>Triple covalent bond</p> Signup and view all the answers

    How is molecular weight defined?

    <p>The sum of the masses of all the atoms in a molecule</p> Signup and view all the answers

    What is the molarity of a solution?

    <p>Number of moles of solute per liter of solution</p> Signup and view all the answers

    What determines an atom's electronegativity?

    <p>A combination of the number of protons and the atomic radius</p> Signup and view all the answers

    What type of bond results from unequal sharing of electrons?

    <p>Polar covalent bond</p> Signup and view all the answers

    What charge develops around the more electronegative atom in a polar covalent bond?

    <p>Partial negative charge</p> Signup and view all the answers

    Which molecule would most likely contain the largest number of polar covalent bonds?

    <p>C2H4O2 (acetic acid)</p> Signup and view all the answers

    What type of bond involves a complete transfer of electrons between atoms?

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

    Which of the following is true about polar molecules?

    <p>They tend to be hydrophilic.</p> Signup and view all the answers

    What are negatively charged ions called?

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

    Which force is responsible for the attractions between nonpolar molecules?

    <p>Van der Waals forces</p> Signup and view all the answers

    What happens to ionic bonds when salt is introduced into water?

    <p>They are interfered with by water's partial charges.</p> Signup and view all the answers

    In a chemical reaction, what are the substances called that are converted to products?

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

    What type of bond do not share electrons?

    <p>Hydrogen bonds</p> Signup and view all the answers

    What is the primary characteristic of hydrophobic molecules?

    <p>They do not dissolve in water.</p> Signup and view all the answers

    What must occur in a chemical equation to comply with the law of conservation of mass?

    <p>The equation must balance the number of atoms on both sides.</p> Signup and view all the answers

    Which statement correctly defines a calorie?

    <p>The amount of heat needed to raise the temperature of one gram of water from 14.5°C to 15.5°C.</p> Signup and view all the answers

    What characterizes a 1 molar (1 M) solution of NaCl?

    <p>It is created by dissolving 58.5 grams of NaCl in one liter of water.</p> Signup and view all the answers

    Which of the following describes how water behaves when it freezes?

    <p>Water expands upon freezing and ice is less dense than liquid water.</p> Signup and view all the answers

    How does the mole concept aid in quantitative analysis?

    <p>It defines the amount of substance as grams equal to its molecular weight.</p> Signup and view all the answers

    What role does water play in living organisms?

    <p>It serves as a solvent for many biochemical reactions.</p> Signup and view all the answers

    What property of water is primarily responsible for its ability to form hydrogen bonds?

    <p>The bent shape and polarity of water molecules.</p> Signup and view all the answers

    Why do chemical bonds store potential energy?

    <p>They create a stable and low-energy arrangement of atoms.</p> Signup and view all the answers

    What is the primary reason ice floats in liquid water?

    <p>Ice is less dense than liquid water.</p> Signup and view all the answers

    What does specific heat indicate in the context of liquid water?

    <p>The amount of heat required to raise the temperature of 1 gram by 1°C.</p> Signup and view all the answers

    What property of water contributes to its high surface tension?

    <p>Cohesion due to hydrogen bonds.</p> Signup and view all the answers

    Which of the following statements is true regarding the specific heat of water?

    <p>It is approximately 4 Joules per gram per degree Celsius.</p> Signup and view all the answers

    How does water's cohesive strength affect its movement in trees?

    <p>It enables water transport from roots to leaves.</p> Signup and view all the answers

    What happens to water when it freezes?

    <p>It loses energy and expands.</p> Signup and view all the answers

    What defines an acid in terms of its behavior in water?

    <p>It donates hydrogen ions.</p> Signup and view all the answers

    What is the relationship between the polarity of a substance and the energy required to change its temperature?

    <p>Higher polarity requires more energy to change temperature.</p> Signup and view all the answers

    Study Notes

    Life and Chemistry: Small Molecules

    • Atoms are the fundamental building blocks of matter.
    • Chemical bonds connect atoms together, forming molecules.
    • Chemical reactions involve atoms changing partners.
    • Water has unique properties crucial for life.
    • Acids, bases, and the pH scale describe how acidic or basic a substance is.
    • Properties of molecules are influenced by their composition, structure, reactivity, and solubility. Functional groups and isomerism are important concepts.

    Objectives (ILOs)

    • Students should be familiar with chemical terminology.
    • Understand the basics of atoms and their properties including energy levels and orbitals.
    • Develop a strong understanding of various chemical bonds (between atoms and molecules)
    • Understand the properties of water
    • Know the concept of kinetic energy and heat.
    • Ability to calculate the pH of a substance.
    • Understand the concept of isomers and apply it in context
    • Students should understand various functional groups' importance.
    • Understand the function of carbon atoms

    Atoms: The Constituents of Matter

    • Matter consists of atoms.
    • Atomic structure dictates element behavior.
    • Atoms are comprised of protons, neutrons, and electrons.
    • Elements have unique atomic numbers (protons).
    • Mass numbers are the sum of protons and neutrons.
    • Atomic weight is the average mass of naturally occurring isotopes.
    • Each element has a unique symbol and is organized in a table (periodic table)
    • Electron shells or energy levels surround the nucleus.
    • Each shell has a limited number of electrons.
    • valence shell is the outermost shell and determines reactivity.
    • Valence electrons participate in bonding

    Atoms: The Octet Rule

    • Atoms are typically stable when their outer shell has eight electrons (octet rule)
    • Atoms without a full octet will gain, lose, or share electrons to achieve stability.

    Chemical Bonds: Linking Atoms Together

    • Molecules form when atoms bond.
    • Covalent bonds form by sharing pairs of electrons.
    • In covalent bonds atoms with different electronegativities form polar covalent bonds.
    • Hydrogen bonds form weak attractions between slightly charged portions of polar molecules.
    • Ionic bonds form by complete transfer of electrons.

    Quantifying Molecules

    • Molecular weight is the sum of the atomic weights of atoms in a molecule
    • One mole equals 6.022 × 10²³ molecules
    • Molarity (M) measures concentration as the number of moles per liter

    Water: Structure and Properties

    • Water is essential for life.
    • Water is a polar molecule because of unequal electron sharing.
    • Exceptional Properties:
      • High Specific heat (ability to absorb or release heat)
      • High Heat of vaporization (energy to convert water to gas).
      • Cohesion and adhesion of water molecules (important in transport).
      • Ice's density is less than liquid water.
      • Water is an excellent solvent for other polar or ionic substances.

    Acids, Bases, and the pH Scale

    • Acids release H+ and bases release OH-
    • pH scale measures acidity.
    • Buffer solutions resist pH changes.

    Properties of Molecules

    • Molecules are classified based on their structure, composition, reactivity, and solubility.
    • Functional groups are components responsible for the unique properties of molecules
    • Isomers exhibit same chemical formula but different atomic arrangements.

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    Lecture 2, Life and Chemistry: Small Molecules PDF

    Description

    This quiz covers essential concepts in chemistry, focusing on small molecules and their properties. Students will examine the structure of atoms, chemical bonds, and the significance of water's unique properties. Key topics include pH scale, functional groups, and isomerism, providing a foundation for understanding chemical reactions and terminology.

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