Overview
This lecture introduces the basic chemistry concepts underlying life, focusing on the structure of matter, atomic components, types of chemical bonds, and how these concepts apply to biological molecules and physiology.
Matter and Atoms
- Matter is anything that takes up space and has mass, including solids, liquids, gases, and plasma.
- Atoms are the smallest stable units of matter, made of subatomic particles: protons, neutrons, and electrons.
- Protons (positive charge) and neutrons (neutral) are located in the nucleus, while electrons (negative charge) orbit in the electron cloud.
Subatomic Particles & Atomic Structure
- Protons determine atomic identity and contribute to mass; neutrons add mass but no charge; electrons add charge but negligible mass.
- Atomic mass = number of protons + number of neutrons.
- Atomic charge = number of protons (positive) - number of electrons (negative).
Elements, Atomic Number, and Isotopes
- Elements are pure substances consisting of only one type of atom; defined by atomic number (number of protons).
- Isotopes are atoms of the same element with different numbers of neutrons, resulting in different masses.
- The atomic mass on the periodic table is the weighted average of all isotopes.
Electron Shells & Valence Electrons
- Electrons occupy shells/energy levels around the nucleus; shells fill in order (2 in the first, then 8 in the next, etc.).
- The outermost shell is the valence shell; valence electrons determine chemical reactivity.
- Atoms react to achieve a full valence shell, making them stable.
Molecules, Compounds, and Chemical Bonds
- Molecule: two or more atoms bonded together.
- Compound: molecule containing atoms of different elements.
- Atoms bond by sharing or transferring electrons to fill valence shells.
Types of Chemical Bonds
- Ionic bonds: formed through transfer of electrons, creating charged ions (cation = positive, anion = negative).
- Covalent bonds: formed by sharing pairs of electrons; can be single, double, or triple bonds.
- Nonpolar covalent bonds share electrons equally; polar covalent bonds share unequally, producing partial charges.
- Hydrogen bonds: weak attractions between partial positive and negative regions of polar molecules.
Biological Relevance
- The properties of elements and bonds (especially in water) explain key biological processes like metabolism and transport in the body.
- Water's polarity and hydrogen bonding explain its unique properties essential for life.
Key Terms & Definitions
- Matter — anything with mass that occupies space.
- Atom — the smallest unit of an element, made of protons, neutrons, and electrons.
- Element — a pure substance of one type of atom, defined by number of protons.
- Isotope — atoms of the same element with different numbers of neutrons.
- Valence Shell — the outermost electron shell, involved in chemical bonding.
- Ion — a charged atom (cation = positive, anion = negative).
- Molecule — two or more atoms joined together.
- Compound — a molecule with at least two different elements.
- Ionic Bond — bond formed by transfer of electrons between ions.
- Covalent Bond — bond formed by sharing electrons between atoms.
- Hydrogen Bond — weak bond between partial charges in polar molecules.
Action Items / Next Steps
- Read and review the chemical notation and symbols for atoms, molecules, and ions.
- Be able to identify if a structure is an atom, molecule, or compound.
- Practice calculating protons, neutrons, electrons, atomic mass, and charge.
- Prepare questions for the next lecture if unclear on any concepts.