CHEM 1010 Week 3: Atoms and Elements
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Questions and Answers

What is the smallest identifiable unit of an element?

  • Compound
  • Isotope
  • Molecule
  • Atom (correct)

    • Which law states that matter is neither created nor destroyed in a chemical reaction?

  • Law of Atomic Theory
  • Law of Multiple Proportions
  • Law of Definite Proportions
  • Law of Conservation of Mass (correct)

    • How many naturally occurring elements are there?

  • 72
  • 85
  • 91 (correct)
  • 100

    • Which of the following is not an element?

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

    Which two elements are involved in forming salt?

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

    The law of multiple proportions indicates that when two elements form more than one compound, the mass of one element that combines with a fixed mass of the other can be expressed as a ratio of small whole numbers. What does this mean?

    <p>There are fixed ratios for combinations of elements.</p> Signup and view all the answers

    What does the modern atomic theory suggest about matter?

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

    Which of the following correctly describes the composition of an isotope?

    <p>Different number of neutrons</p> Signup and view all the answers

    Which element contains 50 protons in its nucleus?

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

    How many neutrons are present in neon-20?

    <p>10</p> Signup and view all the answers

    What term describes atoms with the same number of protons but different numbers of neutrons?

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

    What is the primary role of protons in an atom?

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

    According to Dalton's atomic theory, what is true about atoms?

    <p>Atoms combine in simple, whole-number ratios</p> Signup and view all the answers

    What is the natural abundance of neon-21?

    <p>0.27%</p> Signup and view all the answers

    What isotope of argon has a mass number of 40?

    <p>Argon-40</p> Signup and view all the answers

    Which particle in an atom has a charge of zero?

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

    What observation supports the law of multiple proportions?

    <p>The same mass ratios of elements forming different compounds</p> Signup and view all the answers

    What is the mass number of neon if it has 12 neutrons?

    <p>22</p> Signup and view all the answers

    Which of the following isotopes of neon has the highest natural abundance?

    <p>Ne-20</p> Signup and view all the answers

    Which of the following statements about electrons is true?

    <p>Electrons are responsible for most chemical behavior</p> Signup and view all the answers

    If a neutral atom of neon has 10 protons, how many electrons does it have?

    <p>10</p> Signup and view all the answers

    What is the definition of atomic number (Z)?

    <p>Number of protons in an atom's nucleus</p> Signup and view all the answers

    Which of the following elements has the symbol 'Au'?

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

    Which of the following best describes a neutron's charge?

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

    How are chemical symbols formatted for elements?

    <p>First letter is always capitalized and the second letter is lowercase</p> Signup and view all the answers

    What is the main difference between protons and electrons in terms of charge?

    <p>Protons have a positive charge, while electrons have a negative charge</p> Signup and view all the answers

    What characteristic is common to metals?

    <p>Can be drawn into wires</p> Signup and view all the answers

    Which of the following is classified as a nonmetal?

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

    Which group of elements exhibits mixed properties that are characteristic of both metals and nonmetals?

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

    What is true about nonmetals in comparison to metals?

    <p>Nonmetals are poor conductors of heat and electricity.</p> Signup and view all the answers

    How many total nonmetals are there in the periodic table?

    <p>17</p> Signup and view all the answers

    Which element is a liquid at room temperature?

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

    In the periodic table, what is the significance of a group's number?

    <p>It suggests similar chemical properties among the elements.</p> Signup and view all the answers

    What does the periodic table's diagonal line represent?

    <p>The separation between metals and nonmetals</p> Signup and view all the answers

    What charge do alkali metals typically form when they lose an electron?

    <p>+1</p> Signup and view all the answers

    How do the charges of main-group elements that form cations relate to their group number?

    <p>The charge is equal to the group number.</p> Signup and view all the answers

    What is the typical charge of halogens when they gain an electron?

    <p>-1</p> Signup and view all the answers

    Which statement regarding the formation of anions is accurate?

    <p>Group 6A elements form -2 anions.</p> Signup and view all the answers

    What does atomic mass represent for an element?

    <p>The average mass of the isotopes, weighted by their natural abundance.</p> Signup and view all the answers

    In the periodic table, where is the atomic mass located for each element?

    <p>Below the element's symbol.</p> Signup and view all the answers

    What happens to the number of electrons when transition elements form ions?

    <p>They can lose varying numbers of electrons, leading to different charges.</p> Signup and view all the answers

    How is the atomic mass of chlorine calculated based on its isotopes?

    <p>Multiply each isotope's mass by its percent abundance and add them.</p> Signup and view all the answers

    Study Notes

    Atoms and Elements

    • An atom is the smallest identifiable unit of an element, composed of protons, neutrons, and electrons.
    • Carbon atoms cannot be further divided without losing their identity as carbon.
    • There are about 91 naturally occurring elements and over 20 synthetic elements.

    Modern Atomic Theory

    • Key laws that led to atomic theory:
      • Law of conservation of mass: Matter is neither created nor destroyed in chemical reactions.
      • Law of definite proportions: Compounds always contain elements in fixed ratios.
      • Law of multiple proportions: Elements can combine in different ratios to form different compounds.

    Structure of the Atom

    • Nucleus: central part of the atom, contains protons and neutrons, holds 99% of an atom's mass.
    • Electrons: negatively charged particles orbiting outside the nucleus, with negligible mass.

    Subatomic Particles

    • Protons: found in the nucleus, positively charged, and define the atomic number (Z), which determines the element.
    • Neutrons: also in the nucleus, neutral charge, contribute to the mass number.
    • The charge of protons and electrons is equal in magnitude but opposite in sign.

    Isotopes

    • Isotopes are variants of elements with the same number of protons but different numbers of neutrons.
    • Neon has isotopes with mass numbers of 20 (10 neutrons), 21 (11 neutrons), and 22 (12 neutrons).
    • Natural abundance refers to the relative amount of each isotope in a sample.

    Periodic Table

    • The periodic table is organized into groups (vertical columns) and periods (horizontal rows).
    • Groups correspond to elements with similar chemical properties and predictable behavior in reactions.
    • Elements are classified as metals, nonmetals, and metalloids based on their properties.

    Metals, Nonmetals, Metalloids

    • Metals: good conductors of heat and electricity, ductile, malleable, typically lose electrons.
    • Nonmetals: poor conductors, not ductile or malleable, typically gain electrons.
    • Metalloids: exhibit properties of both metals and nonmetals, often semiconductors.

    Ions

    • Cations are formed when main-group metals lose electrons and have charges equal to their group number.
    • Anions are formed when nonmetals gain electrons, and the charge equals their group number minus eight.
    • Transition metals can form various ions with different charges.

    Atomic Mass

    • Atomic mass represents the weighted average mass of an element’s isotopes based on natural abundance.
    • Example: Chlorine's atomic mass calculation involves averaging its isotopes’ masses weighted by their respective abundances.

    Practice Calculations

    • Proficiency in determining the number of protons, electrons, and neutrons in isotopes.
    • Ability to identify an element's position in the periodic table based on its atomic number and group.

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    Week 3: Atoms and Elements CHEM 1010 PDF

    Description

    This quiz covers the fundamentals of atoms and elements, focusing on their structure and characteristics. You will be asked to explain atomic structure, identify elements and their symbols, and perform calculations related to protons, electrons, and neutrons. Prepare to also navigate the periodic table and recognize different groups of elements.

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