Unit 2 Review: Basic Atomic Structure, Isotopes, Average Atomic Mass, and Ions

Basic Atomic Structure and Subatomic Particles

• Lithium Atom Structure:

  • Diagram Components:
    • Nucleus: Contains $3$ protons ($p^+$) and $4$ neutrons ($n^0$).
    • First Energy Level (Inner Shell): Contains $2$ electrons ($e^-$).
    • Second Energy Level (Outer Shell): Contains $1$ electron ($e^-$).
  • Element Identification: The element is Lithium ($\text{Li}$). The number of protons (atomic number) determines the identity of the element.

• Neutral Atom Analysis ($\text{Atomic Number } Z = 12$, $\text{Mass Number } A = 25$):

  • Subatomic Particles:
    • Protons ($p^+$): $12$
    • Neutrons ($n^0$): Calculated as $\text{Mass Number} - \text{Atomic Number} = 25 - 12 = 13$
    • Electrons ($e^-$): $12$ (equal to the number of protons in a neutral atom)
  • Element Identification: Magnesium ($\text{Mg}$)

Reading the Periodic Table and Atomic Calculations

• Subatomic Calculations for Neutral Atoms:

  • For any neutral atom:
    • $\text{Atomic Number } (Z) = \text{Number of Protons } (p^+) = \text{Number of Electrons } (e^-)$
    • $\text{Mass Number } (A) = \text{Number of Protons } (p^+) + \text{Number of Neutrons } (n^0)$
    • $\text{Number of Neutrons } (n^0) = \text{Mass Number } (A) - \text{Atomic Number } (Z)$

• Neutral Atoms Data Table:

  • Beryllium ($\text{Be}$):
    • $\text{Atomic Number } (Z) = 4$
    • $\text{Mass Number } (A) = 9$
    • $\text{Number of Protons } (p^+) = 4$
    • $\text{Number of Neutrons } (n^0) = 5$
    • $\text{Number of Electrons } (e^-) = 4$
  • Helium ($\text{He}$):
    • $\text{Atomic Number } (Z) = 2$
    • $\text{Mass Number } (A) = 4$
    • $\text{Number of Protons } (p^+) = 2$
    • $\text{Number of Neutrons } (n^0) = 2$
    • $\text{Number of Electrons } (e^-) = 2$
  • Phosphorus ($\text{P}$):
    • $\text{Atomic Number } (Z) = 15$
    • $\text{Mass Number } (A) = 31$
    • $\text{Number of Protons } (p^+) = 15$
    • $\text{Number of Neutrons } (n^0) = 16$
    • $\text{Number of Electrons } (e^-) = 15$
  • Titanium ($\text{Ti}$):
    • $\text{Atomic Number } (Z) = 22$
    • $\text{Mass Number } (A) = 48$
    • $\text{Number of Protons } (p^+) = 22$
    • $\text{Number of Neutrons } (n^0) = 26$
    • $\text{Number of Electrons } (e^-) = 22$
  • Gold ($\text{Au}$):
    • $\text{Atomic Number } (Z) = 79$
    • $\text{Mass Number } (A) = 197$
    • $\text{Number of Protons } (p^+) = 79$
    • $\text{Number of Neutrons } (n^0) = 118$
    • $\text{Number of Electrons } (e^-) = 79$

Isotopes and Notations

• Gallium Isotopes Comparison ($\text{Gallium-69}$ and $\text{Gallium-71}$):

  • Shared Particle: Both isotopes share identical numbers of protons ($31$ protons each).
  • Neutron Difference:
    • $\text{Gallium-69}$ has $69 - 31 = 38$ neutrons.
    • $\text{Gallium-71}$ has $71 - 31 = 40$ neutrons.
    • $\text{Gallium-69}$ has $2$ fewer neutrons than $\text{Gallium-71}$.

• Silicon Isotope Nuclear Notation Construction:

  • Given: $\text{Atomic Number } (Z) = 14$, $\text{Neutrons } (n^0) = 16$
  • $\text{Mass Number } (A) = 14 + 16 = 30$
  • Nuclear Notation: $^{30}\text{Si}$

• Bromine-81 Isotope Breakdown:

  • Hyphen Notation: $\text{Bromine-81}$
  • Protons ($p^+$): $35$
  • Neutrons ($n^0$): $81 - 35 = 46$
  • Electrons ($e^-$): $35$

• Isotope Notations and Subatomic Summary Table:

  • Copper-63:
    • Hyphen Notation: $\text{Copper-63}$
    • Nuclear Notation: $^{63}\text{Cu}$
    • Atomic Number ($Z$): $29$
    • Mass Number ($A$): $63$
    • Protons ($p^+$): $29$
    • Neutrons ($n^0$): $34$
    • Electrons ($e^-$): $29$
  • Copper-65:
    • Hyphen Notation: $\text{Copper-65}$
    • Nuclear Notation: $^{65}\text{Cu}$
    • Atomic Number ($Z$): $29$
    • Mass Number ($A$): $65$
    • Protons ($p^+$): $29$
    • Neutrons ($n^0$): $36$
    • Electrons ($e^-$): $29$
  • Neon-22:
    • Hyphen Notation: $\text{Neon-22}$
    • Nuclear Notation: $^{22}\text{Ne}$
    • Atomic Number ($Z$): $10$
    • Mass Number ($A$): $22$
    • Protons ($p^+$): $10$
    • Neutrons ($n^0$): $12$
    • Electrons ($e^-$): $10$

Average Atomic Mass and Natural Abundance

• Concept of Average Atomic Mass:

  • The average atomic mass of chlorine ($35.45\,\text{amu}$) is a weighted average of all naturally occurring isotopes of chlorine ($\text{Chlorine-35}$ and $\text{Chlorine-37}$) based on their relative natural abundances, rather than the mass of any single individual atom.

• Average Atomic Mass Calculation Example:

  • Given an element with two naturally occurring isotopes:
    • Isotope 1: Mass = $35\,\text{amu}$, Abundance = $75\%$ ($0.75$)
    • Isotope 2: Mass = $37\,\text{amu}$, Abundance = $25\%$ ($0.25$)
  • Calculation:
    • $\text{Average Atomic Mass} = (35\,\text{amu} \times 0.75) + (37\,\text{amu} \times 0.25)$
    • $\text{Average Atomic Mass} = 26.25\,\text{amu} + 9.25\,\text{amu} = 35.5\,\text{amu}$

• Determining Relative Abundance from Average Atomic Mass:

  • For Lithium, $\text{Lithium-7}$ is more naturally abundant than $\text{Lithium-6}$ because the weighted average atomic mass on the periodic table ($6.94\,\text{amu}$) is significantly closer to $7$ than to 6$.\n\n\n# Atoms vs. Ions\n\n* **Fundamental Difference Between Neutral Atoms and Ions:**\n * **Neutral Atom:** Contains an equal number of protons (p^+$) and electrons ($e^-), resulting in a net electrical charge of zero.\n * **Ion:** Forms when an atom gains or loses electrons, resulting in an unequal number of protons and electrons and producing a net positive charge (cation) or net negative charge (anion).\n\n* **Magnesium Ion Analysis (^{24}\text{Mg}^{2+}):**\n * **Symbol / Notation:** ^{24}\text{Mg}^{2+}\n * **Protons (p^+$):**$12\n * **Neutrons (n^0$):** Calculated as$24 - 12 = 12\n * **Electrons (e^-$):** Calculated as$12 - 2 = 10$(loses$2$electrons to form a$2+ charge)\n\n* **Atoms and Charged Ions Summary Table:**\n * **Potassium (^{39}\text{K}):**\n * **Classification:** Atom\n * **Atomic Number (Z$):**$19\n * **Mass Number (A$):**$39\n * **Protons (p^+$):**$19\n * **Neutrons (n^0$):**$20\n * **Electrons (e^-$):**$19\n * **Oxide Ion (^{16}\text{O}^{2-}):**\n * **Classification:** Ion\n * **Atomic Number (Z$):**$8\n * **Mass Number (A$):**$16\n * **Protons (p^+$):**$8\n * **Neutrons (n^0$):**$8\n * **Electrons (e^-$):**$10$(gained$2 electrons)\n * **Aluminum (^{27}\text{Al}):**\n * **Classification:** Atom\n * **Atomic Number (Z$):**$13\n * **Mass Number (A$):**$27\n * **Protons (p^+$):**$13\n * **Neutrons (n^0$):**$14\n * **Electrons (e^-$):**$13\n * **Phosphide Ion (^{31}\text{P}^{3-}):**\n * **Classification:** Ion\n * **Atomic Number (Z$):**$15\n * **Mass Number (A$):**$31\n * **Protons (p^+$):**$15\n * **Neutrons (n^0$):**$16\n * **Electrons (e^-$):**$18$(gained$3$$ electrons)