Overview
This lecture introduces the chemical foundations of life, focusing on atomic structure, types of chemical bonds, properties of water and carbon, and basic terms in chemistry relevant to biology.
Matter and Elements
- Matter is anything that occupies space and has mass.
- Matter exists in three states: solid, liquid, and gas.
- Mass measures the amount of material in an object.
- An element is a substance that cannot be broken down by chemical reactions.
- Elements are identified by chemical symbols (e.g., S for sulfur, Ca for calcium).
- The four most common elements in living organisms are carbon, oxygen, hydrogen, and nitrogen.
- Elements in living organisms have higher concentrations of C, H, O, and N compared to non-living matter.
Atoms and Atomic Structure
- Atoms are the smallest unit of matter retaining the properties of an element.
- An atom consists of a nucleus (center) and electrons orbiting around it.
- The nucleus contains protons (positively charged) and neutrons (no charge).
- Electrons are negatively charged and found in orbitals surrounding the nucleus.
- Hydrogen is an exception, with one proton and one electron, but no neutrons.
- Protons and neutrons have about the same mass (1 atomic mass unit, AMU).
- Atoms are neutral when they have equal numbers of protons and electrons.
Atomic Number, Mass, and Isotopes
- The number of protons in an atom determines its atomic number and element.
- The atomic mass is the sum of protons and neutrons in an atom.
- Electrons are excluded from atomic mass calculations due to their minimal mass.
- Isotopes are different forms of the same element with varying numbers of neutrons.
- Atomic mass is expressed in atomic mass units (AMU).
Key Terms & Definitions
- Matter — anything that occupies space and has mass.
- Element — a substance that cannot be broken down by chemical reactions.
- Atom — the smallest unit of an element retaining its properties.
- Proton — subatomic particle with a positive charge, found in the nucleus.
- Neutron — subatomic particle with no charge, found in the nucleus.
- Electron — subatomic particle with a negative charge, orbits the nucleus.
- Atomic Number — number of protons in an atom, defines the element.
- Atomic Mass — total number of protons and neutrons in an atom.
- Isotope — atoms of the same element with different numbers of neutrons.
- AMU (Atomic Mass Unit) — unit for measuring atomic mass.
Action Items / Next Steps
- Review the periodic table for atomic numbers and symbols.
- Read textbook sections on atomic structure and isotopes.
- Prepare for upcoming discussions on chemical bonds, water, and carbon properties.