Overview
This lecture introduces the concepts of matter, atoms, elements, and compounds, highlighting their definitions, characteristics, and relationships.
Matter and Its Properties
- Matter is anything that has mass and takes up space.
- Matter is distinct from energy; energy is not matter.
Atoms and Elements
- Atoms are the smallest units of an element that retain the properties of that element.
- An element is a type of matter that cannot be chemically converted into another element.
- Each element has a unique symbol, often one or two letters, from the periodic table.
- Examples of elements: carbon (C), gold (Au), hydrogen (H), helium (He), neon (Ne), fluorine (F), and oxygen (O).
- Chemical reactions cannot change one element into a different element.
Compounds
- Compounds are formed when atoms of different elements combine in specific ratios.
- Compounds have properties different from the elements that compose them.
- Water (H₂O) is a compound made of two hydrogen atoms and one oxygen atom.
- Sodium chloride (NaCl), or table salt, is a compound made from one sodium atom (Na) and one chlorine atom (Cl).
- Sodium is a reactive metal, and chlorine is a toxic gas, but together they form non-toxic, edible table salt.
Key Terms & Definitions
- Matter — Anything with mass that takes up space.
- Atom — The smallest part of an element that retains its properties.
- Element — A substance that cannot be chemically converted into another by ordinary means.
- Compound — A substance made from atoms of different elements bonded together in fixed ratios.
Action Items / Next Steps
- Familiarize yourself with key chemical symbols (e.g., H, O, Na, Cl).
- Review the periodic table and recognize element symbols.
- Understand the differences between elements and compounds.