Atomic Structure and Subatomic Particles
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Questions and Answers

What defines the atomic number of an atom?

  • The number of protons in the atom (correct)
  • The total number of electrons in the atom
  • The total mass of protons and neutrons
  • The total number of neutrons in the atom

    • Which subatomic particle is neutral in charge?

  • Electron
  • Neutron (correct)
  • Positron
  • Proton

    • How is mass number defined?

  • The total mass of the atom in grams
  • The number of protons plus the number of neutrons (correct)
  • The number of protons plus the number of electrons
  • The number of electrons in the outer shell

    • If an atom has 20 protons, how many electrons does it have?

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

    What distinguishes different isotopes of the same element?

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

    Which of the following statements is true regarding electrons?

    <p>They balance the positive charge of protons in a neutral atom.</p> Signup and view all the answers

    What is the mass of a neutron in kilograms?

    <p>1.675 × 10−27</p> Signup and view all the answers

    If an atom's mass number is 3 and its atomic number is 1, how many neutrons does it possess?

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

    What do the angular momentum quantum numbers indicate?

    <p>The shape of the orbital</p> Signup and view all the answers

    According to Hund's Rule, how are electrons distributed in orbitals of equal energy?

    <p>One electron is added to each orbital before pairing</p> Signup and view all the answers

    What is the maximum number of electrons that can be held in the second energy level?

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

    Which of the following describes an isotope?

    <p>Atoms with the same number of protons but different neutrons</p> Signup and view all the answers

    What principle states that only two electrons can occupy an orbital and must have paired spins?

    <p>Pauli Exclusion Principle</p> Signup and view all the answers

    Which orbital type corresponds to the angular momentum quantum number L=1?

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

    How many orbitals are present in the d sublevel?

    <p>5</p> Signup and view all the answers

    What describes the energy level of electrons filling according to the Aufbau principle?

    <p>From lowest energy to highest</p> Signup and view all the answers

    How many neutrons are present in lithium (Li) with a mass number of 7 and an atomic number of 3?

    <p>4</p> Signup and view all the answers

    According to the Bohr model, which statement about electron orbits is correct?

    <p>The first orbit can hold up to 2 electrons.</p> Signup and view all the answers

    What is the primary focus of the Electron Cloud model?

    <p>It presents a cloud-like region indicating where electrons are likely to be.</p> Signup and view all the answers

    Which quantum number indicates the main energy level of an electron?

    <p>Principal quantum number</p> Signup and view all the answers

    What is the maximum number of electrons that can occupy the third orbit according to the Bohr model?

    <p>18</p> Signup and view all the answers

    What do the values of the angular momentum quantum number (l) represent?

    <p>The shape or type of orbital</p> Signup and view all the answers

    How is the number of protons (P+) in an atom related to its atomic number?

    <p>Atomic number equals the number of protons.</p> Signup and view all the answers

    In a neutral atom, how does the number of electrons (e-) compare to the number of protons (P+)?

    <p>Electrons equal the number of protons.</p> Signup and view all the answers

    Study Notes

    Atomic Structure

    • Atoms are the fundamental building blocks of matter
    • Matter is anything that occupies space and has mass
    • Understanding atomic structure is key to understanding the properties of matter
    • Atoms consist of subatomic particles: electrons, protons, and neutrons

    Subatomic Particles

    • Subatomic particles make up atoms
    • Many subatomic particles exist but the three most important for chemistry are: electrons, protons, and neutrons
    • Electrons have a negative charge
    • Protons have a positive charge
    • Neutrons have no charge

    Properties of Subatomic Particles

    Particle Symbol Charge Mass (kg)
    Electron e- -1 9.109 x 10-31
    Proton p+ +1 1.673 x 10-27
    Neutron n0 0 1.675 x 10-27

    Atomic Structure: Atom

    • Atoms are electrically neutral because the number of protons equals the number of electrons
    • Protons and neutrons are located in the nucleus of an atom
    • Electrons orbit the nucleus

    Atomic Number

    • The atomic number identifies an element
    • The atomic number equals the number of protons in an atom
    • Example: Hydrogen's atomic number is 1, meaning it has 1 proton.

    Mass Number

    • Mass number is the sum of protons and neutrons in an atom
    • Example: If an atom has a mass number of 3 and an atomic number of 1 (Hydrogen), it has 2 neutrons (3-1=2).
    • The number of neutrons = mass number - atomic number

    Determining the Number of Subatomic Particles

    • Using the mass and atomic numbers, the number of protons, neutrons, and electrons can be calculated for any atom
    • Example: Lithium (Li) has atomic number 3 and mass number 7 = 3 protons, 4 neutrons, 3 electrons.

    Bohr's Model

    • Atoms have a centrally located, positively charged nucleus containing protons and neutrons
    • Electrons orbit the nucleus in specific energy levels or shells/orbits
    • Each electron shell can only hold a specific number of electrons (2n2)

    Bohr Model of the atom (2n2):

    • The first shell can hold a maximum of 2 electrons
    • The second shell can hold a maximum of 8 electrons
    • The third shell can hold a maximum of 18 electrons

    Electron Cloud Model

    • The electron cloud represents the probability of finding an electron in a particular region around the nucleus
    • The electron cloud model is a more complex and modern way of visualizing electron distribution compared to the Bohr model.
    • Electrons exist in a cloud-like orbital around the nucleus
    • Electrons are not confined to specific paths.

    Quantum Numbers

    • Quantum numbers describe the properties of atomic orbitals and the electrons within them
    • Quantum numbers are used to characterize the energy levels, angular momentum, magnetic properties, and spin of each electron in an atom
    • Four quantum numbers describe each electron:
      • Principal quantum number (n): indicates the main energy level of the electron
        • Angular momentum quantum number (l): describes the shape of the orbital
        • Magnetic quantum number (ml ): specifies the orientation of the orbital
      • Spin Quantum Number (s): the electron spin

    Sublevel Names

    Angular momentum (l) Sublevel name (s, p, d, f)
    0 s
    1 p
    2 d
    3 f

    Electron Configuration

    • Describes the arrangement of electrons in an atom's energy levels and sublevels
    • Electrons occupy orbitals following principles like the Aufbau principle (filling orbitals from lowest to highest energy), Hund's rule (filling orbitals evenly before pairing up electrons), and Pauli exclusion principle (no two electrons in the same atom can have the same set of four quantum numbers)

    Isotopes

    • Isotopes have the same number of protons but different numbers of neutrons
    • Therefore, isotopes of an element have different mass numbers but same atomic number

    Elements

    • An element is a substance that is made entirely from one type of atom
    • Scientists have identified 90 naturally occurring elements and made 28 more

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    Atomic Structure - 2 - PDF

    Description

    Explore the fundamentals of atomic structure and the essential subatomic particles that make up atoms. This quiz covers the properties of electrons, protons, and neutrons, highlighting their charges and masses. Understanding these concepts is crucial for grasping the properties of matter.

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