Chem 1

Introduction to Chemistry

• Chemistry is the study of matter, its properties, composition, and behavior.

• It is often called the central science because it connects physical sciences with life sciences and applied sciences.

Basic Principles of Chemistry

Matter

• Matter is anything that has mass and occupies space.

• It can exist in three states: solid, liquid, and gas.

Atoms

• Atoms are the smallest units of elements.

• Each atom consists of three main types of subatomic particles:

  • Protons: Positively charged (+) particles found in the nucleus.

  • Neutrons: Uncharged particles also located in the nucleus.

  • Electrons: Negatively charged (–) particles that orbit the nucleus.

Elements and Compounds

• Elements: Pure substances that cannot be broken down further by chemical means.

  • Examples include oxygen (O), carbon (C), and nitrogen (N).

• Compounds: Substances formed when two or more elements chemically bond together.

  • They can be ionic (electron transfer) or covalent (electron sharing).

Water as a Chemical Substance

Unique Properties of Water

• Water (H2O) is vital for all known forms of life and has unique properties due to its molecular structure:

  • Cohesion: Water molecules stick together, providing surface tension.

  • Adhesion: Water molecules can also stick to other substances.

  • High Heat Capacity: Water can absorb a lot of heat without a significant temperature change, helping regulate temperature.

  • Density Anomaly: Ice floats because it is less dense than liquid water, allowing it to insulate aquatic environments.

Chemical Reactions

• Chemical reactions involve the transformation of substances through breaking and forming bonds:

  • Reactants: Substances that undergo change.

  • Products: New substances formed as a result of the reaction.

• Types of reactions include synthesis, decomposition, and exchange reactions.

Conclusion

• Understanding the principles of chemistry is fundamental for exploring complex systems in both biology and the environment.