Electrons, Orbitals, and Ions: A Deeper Dive into Atomic Structure

Electrons and Atomic Structure

Introduction to Subatomic Particles and Chemical Bonding

  • This lecture continues to focus on subatomic particles, particularly electrons.

  • Electrons play a critical role in chemistry and chemical bonding due to their arrangement and movement.

  • Examples of electron interactions leading to bonding include:

    • Sodium (Na{\text{Na}}) interacting with Chloride (Cl){\text{Cl}}) (ionic bond).

    • Oxygen (O){\text{O}}) bonding with Carbon (C){\text{C}}) (covalent bond).

  • The primary focus will be on electron arrangements, orbitals, and ion formation in ionic bonds.

Review of Atomic Structure

  • Atoms are comprised of: Protons, Neutrons, and Electrons.

  • Charges:

    • Protons: +1+1

    • Electrons: −1-1

    • Neutrons: Neutral (no charge)

  • Mass:

    • Protons and Neutrons carry the significant mass in atoms.

    • Electrons have a relatively irrelevant mass, approximately 1/20001/2000th of a proton or neutron's mass. The true mass of protons and neutrons is already very small, making electron mass negligible.

  • Atomic Mass Units (AMU) are used to measure the structure of the atom.

  • **Atomic Number (Z){\text{Z}}):

    • Indicates the number of protons.

    • Determines the identity of an element (e.g., Oxygen (Z=8Z=8) changing protons to Z=7Z=7 becomes Nitrogen).

    • This number appears above each element's symbol on the periodic table.

    • It is generally stable; changing it changes the element's identity.

  • Ground State:

    • Refers to an atom where the number of protons equals the number of electrons.

    • Changes in the number of electrons lead to ions (positively or negatively charged).

  • Chemical Properties:

    • The number of electrons and protons gives each element specific chemical properties.

    • Changing the number of electrons (forming ions) changes the atom's propensity to form bonds.

  • **Mass Number (A){\text{A}}):

    • The sum of protons and neutrons ({\text{A}} = {\text{#protons}} + {\text{#neutrons}}).

  • Symbolic Representation of Isotopes:

    • ZAE{\text{}}^A_Z{\text{E}}, where E is the element symbol, A is the mass number (superscript), and Z is the atomic number (subscript).

  • Isotopes:

    • Atoms of the same element with different numbers of neutrons (e.g., carbon-12, carbon-14).

    • The atomic mass unit on the periodic table is the weighted average of the natural abundance of an element's isotopes.

History of the Atomic Model

  • John Dalton (1803):

    • Theory: Atoms are indivisible; atoms of a given element are identical; compounds are combinations of different types of atoms.

    • Still Correct: Compounds are combinations of different atoms (e.g., carbon monoxide, sodium chloride).

    • Partially Incorrect: Atoms can be broken down into subatomic particles (protons, neutrons, electrons), not