Introduction to Elements, Atomic Structure, and Chemical Reactions

Fundamentals of Elements

  • Elements are pure substances consisting of only one type of atom.

  • They cannot be broken down or split into simpler substances.

  • Elements are represented by symbols and arranged on the periodic table (e.g., oxygen, gold, carbon).

Atomic Structure and Subatomic Particles

  • An atom is the smallest particle of an element capable of participating in a chemical reaction.

  • Structure: Consists of a central nucleus and surrounding energy levels or shells.

  • Protons (++, located in the nucleus): Actual mass is 1.67262×10−27 kg1.67262 \times 10^{-27}\,kg.

  • Neutrons (neutral, located in the nucleus): Actual mass is 1.67492×10−27 kg1.67492 \times 10^{-27}\,kg.

Electrons (−-, located in shells): Actual mass is 9.10938×10−31 kg9.10938 \times 10^{-31}\,kg.

  • Relative masses are utilized for calculations because actual subatomic masses are too small for everyday use.

Organization of the Periodic Table

  • Developed based on patterns identified by Mendeleev.

  • Columns: Known as Groups (18 total). Key groups include Group 1 (Alkali Metals), Group 2 (Alkaline Earth Metals), and Group 17 (Halogens).

  • Rows: Known as Periods (7 total).

  • Classification: Elements transition from metals on the left to non-metals on the right. The center block consists of Transition Metals.

Chemical Reactions and Atomic Theory

  • Antoine Lavoisier (1789): Established the Law of Conservation of Mass; mass is neither created nor destroyed during a reaction, only transformed.

  • John Dalton's Atomic Theory: Atoms of a specific element are identical; different elements vary by atomic mass; atoms cannot be destroyed but can regroup to form compounds.

  • Reaction Equations: Written as Reactants→Products\text{Reactants} \rightarrow \text{Products}. A plus sign (++) separates multiple reactants or products.

Typical Acid Reactions

  • Acid+Metal→Salt+Hydrogen Gas\text{Acid} + \text{Metal} \rightarrow \text{Salt} + \text{Hydrogen Gas}

  • Acid+Base→Salt+Water\text{Acid} + \text{Base} \rightarrow \text{Salt} + \text{Water}

  • Acid+Metal Carbonate→Salt+Water+Carbon Dioxide Gas\text{Acid} + \text{Metal Carbonate} \rightarrow \text{Salt} + \text{Water} + \text{Carbon Dioxide Gas}

Metal Extraction and Sustainability

  • Metals are obtained from minerals and ores found in the Earth (e.g., CuO(s)+C(s)CuO_{(s)} + C_{(s)}).

  • Environmental Impacts: Mining causes deforestation, water and soil pollution, and contributes to global warming.

  • Social Impacts: Potential for unsafe working conditions, displacement of communities, and destruction of livelihoods.