CHEM1011 Lecture 1 Notes

Types of Particles:
- Atom: Smallest unit in chemistry.
- Element: Only atoms of one type.
- Molecule: Two or more atoms.
- Compound: Two or more atoms of different types.
- Molecules and compounds are overlapping categories.
Matter Classifications:
- Homogeneous: All matter is the same at the atomic level; pure substance.
- Mixture: Multiple different types of substances.
- Heterogeneous: Uneven distribution of substances.
- Homogeneous: Even distribution of substances.
  - Examples:
    - Glass of water (only $H_2O$ ): Homogeneous, pure substance.
    - Seawater (water + salts): Homogeneous mixture.
    - Ocean: Heterogeneous mixture (composition varies with depth).
Elements and Compounds:
- Elements consist of only one type of atom.
- Compounds consist of two or more different elements chemically bonded.
Occurrence in Nature:
- Elements like helium, neon, argon, krypton, xenon, and radon occur as individual atoms (monoatomic).
- Diatomic molecules: Hydrogen, nitrogen, oxygen, fluorine, chlorine, bromine, and iodine.
- All the monoatomic elements exists as a singular atom do not need bonds with other atoms and that there's a common feature of all of those elements.
- The diatomic elements on the other had need to bond with each other and be in a energetic state.

Sulfur ( $S_8$ ): Eight sulfur atoms connected.
Ozone ( $O_3$ ): Three oxygen atoms connected.
Carbon-60 ( $C_{60}$ ): Buckminsterfullerene (buckyball) - network of carbon atoms bonded together.
Extended networks: Some elements can extend indefinitely due to their bonding properties.