Atoms and Elements in Environmental Chemistry

Atoms and Elements

• Atoms are the fundamental building blocks of matter.
• Atoms consist of a nucleus containing protons (positively charged) and neutrons (neutral), surrounded by orbiting electrons (negatively charged).
• Elements are substances composed of only one type of atom.
• Atomic number defines an element, representing the number of protons in the atom's nucleus.
• Atomic mass represents the total mass of protons, neutrons, and electrons.
• Isotopes are atoms of the same element with different numbers of neutrons.
• Electron configuration describes the arrangement of electrons in energy levels and sublevels around the nucleus.
• Periodic table arranges elements based on atomic number.

Chemistry of the Environment

• Environmental chemistry studies chemical processes in the environment.
• Key areas include: air pollution (e.g., acid rain), water pollution (e.g., eutrophication), and soil contamination.
• Environmental chemistry investigates the impact of human activities on the environment, and vice versa.
• Chemical cycles (e.g., carbon, nitrogen, water) are crucial in environmental processes.
• Pollution control and remediation are areas of active research.
• Chemical principles are used to study and address environmental problems.
• Biogeochemical cycles describe the movement of chemical substances through living organisms and the environment.

The Periodic Table

• The periodic table organizes elements based on increasing atomic number and recurring chemical properties.
• Elements with similar properties are placed in vertical columns called groups or families.
• Horizontal rows are called periods.
• Elements are categorized into metals, nonmetals, and metalloids, based on their properties.
• Metals typically conduct electricity and heat, are malleable, ductile, and generally shiny.
• Nonmetals typically do not conduct electricity or heat, are brittle, and may be solid, liquid, or gaseous.
• Metalloids have properties intermediate between metals and nonmetals.
• The table's arrangement reveals trends in atomic radii, ionization energies, and electronegativity.
• Elements exhibit characteristic chemical behavior based on their position in the periodic table.
• Group numbers usually reflect the number of valence electrons, influencing reactivity.

Reacting Masses and Equations

• Stoichiometry involves the calculation of reactants and products in chemical reactions.
• Balanced chemical equations represent the relative amounts of reactants and products involved in a chemical reaction.
• Coefficients in balanced equations represent the mole ratios of reactants and products.
• The law of conservation of mass dictates that mass is neither created nor destroyed in a chemical reaction.
• Molar mass is the mass of one mole of a substance.
• Percentage composition determines the percentage of each element in a compound.
• Empirical formulas represent the simplest whole-number ratio of atoms in a compound.
• Molecular formulas give the actual number of atoms of each element in a compound.
• Limiting reactants determine the maximum amount of product formed in a reaction.
• Yield percentage compares the actual yield of a reaction to the theoretical yield.