Basic Chemistry and Biological Macromolecules

Basic Chemistry and Biological Macromolecules

Atoms and Their Composition

  • Definition of an Atom:

    • Basic unit of matter that comprises all substances.

  • Subatomic Particles:

    • Protons:
    • Positively charged particles found in the nucleus.
    • Symbol: +1
    • Neutrons:
    • Neutral particles located in the nucleus.
    • Electrons:
    • Negatively charged particles that orbit around the nucleus.
    • Symbol: -1

Structure of an Atom

  • Location of Protons and Neutrons:

    • Both are located in the nucleus of the atom.

  • Electron Shells:

    • Electrons occupy orbitals organized in shells:
    • 1st Shell: Max of 2 electrons
    • 2nd Shell: Max of 8 electrons
    • 3rd Shell: Max of 8 electrons (and beyond)

Chemical Bonds

  • Types of Chemical Bonds:
    • Covalent Bonds:
    • Formed by the sharing of electron pairs between atoms.
    • Strong bond type occurring within the same molecule.
    • Involves elements with similar electronegativities to share electrons.
    • Ionic Bonds:
    • Formed from the transfer of electrons from one atom to another, resulting in charged ions.
    • Strong electrostatic attraction between oppositely charged ions.
    • Hydrogen Bonds:
    • A weak bond between a hydrogen atom and an electronegative atom (like oxygen or nitrogen).
    • Creates a relatively strong attraction due to high electronegativity of the atoms.

Key Terms and Concepts

  • Atomic Number (Atomic #):
    • Number of protons in the nucleus of an atom.
  • Mass Number:
    • Total number of protons and neutrons in an atom's nucleus.
  • Electronegativity:
    • Measure of an atom's ability to attract and hold onto shared electrons.
    • In groups:
    • Group 1 has 1 valence electron.
    • Group 13 has 3 valence electrons.
  • Electrons:
    • There are fewer electrons than protons in cations and more electrons than protons in anions.

Summary of Bonding in Molecules

  • Covalent Bonds:
    • Involves sharing of electrons between atoms.
    • Strong bonds that create stable molecules.
  • Ionic Bonds:
    • Formed through the loss and gain of electrons, leading to strong attractions between ions with opposite charges.
    • Generally found in salts or ionic compounds.
  • Hydrogen Bonds:
    • Occur between molecules through partial charges, crucial in biochemistry (e.g., in water and DNA structures).

Implications in Biology

  • Understanding these basic concepts of atom and bond formation is essential for exploring the structure and function of biological macromolecules such as proteins, nucleic acids, carbohydrates, and lipids.