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.