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Chemistry: The Central Science

• Chemistry is known as "the central science" due to its connections with various STEM disciplines, including biology, medicine, and environmental science.

• Basic principles of physics are crucial for understanding many aspects of chemistry.

• Mathematics and computer science are essential tools for interpreting chemical data and phenomena.

• Biochemistry: Convergence of biology and chemistry focusing on processes that keep living organisms alive.

• Chemical Engineering and Nanotechnology: Utilize chemical principles to create substances that range from fuels to electronics.

Importance in Daily Life

• Changes in matter are crucial in everyday activities such as:

  • Digestion and assimilation of food

  • Polymer synthesis for various materials

  • Refining crude oil for gasoline

• Throughout the chemistry course, students will learn about:

  • Changes in composition and structure of matter

  • Classification and causes of these changes

  • Energy changes associated with matter transformations

The Scientific Method

• Chemistry is based on observation and experimentation.

• Common approaches include:

  • Forming a hypothesis - a tentative explanation for observations.

  • Testing hypotheses through experimentation or comparison.

  • Developing scientific laws which summarize many observations.

  • Formulating theories which provide comprehensive explanations.

• The scientific method involves:

  • Moving from questions and observations to laws, hypotheses, and theories through experimental verification.

The Domains of Chemistry

• Chemists study matter and energy behavior in three domains:

  • Macroscopic Domain: Visible and tangible substances (e.g., food, air).

  • Microscopic Domain: Involves particles too small to see, such as atoms and molecules.

  • Symbolic Domain: Involves the representation of macroscopic and microscopic domains using chemical symbols, formulas, and equations.

Example with Water

• Macroscopic observations include:

  • Liquid appearance at moderate temperatures

  • Freezing and boiling points

• Microscopic representation includes:

  • Composition of water (H2O)

  • Molecular interactions during phase changes.

Phases and Classification of Matter

• States of matter:

  • Solids: Rigid shape and definite volume.

  • Liquids: Take the shape of their container and have a definite volume.

  • Gases: Expand to fill their container and take the shape and volume of it.

• Plasma: High-energy state of gas found in stars; contains ionized particles.

Key Properties and Principles

• Matter: Anything that occupies space and has mass.

  • Definition: Mass is the quantity of matter, weight is the gravitational force on that mass.

  • The law of conservation of matter states that matter is neither created nor destroyed in chemical reactions.

• Classification of matter:

  • Pure Substances: Elements (cannot be broken down) and Compounds (composed of two or more elements).

  • Mixtures: Can be homogeneous (uniform composition) or heterogeneous (varying composition).

Examples of Matter:

• Pure Substances: Sucrose has a constant composition.

• Mixtures: Italian dressing (heterogeneous) vs. sports drinks (homogeneous).

Atomic and Molecular Foundations

• Atoms: The smallest unit retaining the properties of an element.

  • Atoms cannot be broken down chemically further.

• Molecules: Combinations of two or more atoms bonded together, can be made from the same or different elements.

  • Examples include diatomic elements (H2, O2) and compounds (H2O, CO2).

Chemistry in Everyday Life

• Decomposition of Water: Water (H2O) decomposes into hydrogen and oxygen gases with energy input, illustrating conservation of mass.

• Cell Phones: Utilize a wide array of chemical substances, showcasing chemistry's impact on technology.

Physical and Chemical Properties

Properties of Matter

• Physical Properties: Observed without changing chemical identity (e.g., density, color).

• Chemical Properties: Characteristics relating to a substance's ability to undergo chemical changes (e.g., flammability).

Physical Changes

• Changes where the composition does not change, such as melting or dissolving.

Chemical Changes

• Changes that result in the formation of new substances (e.g., rusting of iron, combustion).

Measurement and Units

• Measurements consist of:

  • A number (magnitude)

  • A unit (standard of comparison)

  • An uncertainty (degree of error)

• SI Units: International System of Units, includes:

  • Length (meter), mass (kilogram), time (second), temperature (kelvin).

• Derived Units: Units formed from combinations of base units (e.g., density, V = m/V).

Summary of Basic SI Units

• Length (meter, m)

• Mass (kilogram, kg)

• Time (second, s)

• Temperature (kelvin, K)

Conclusion

• Chemistry provides a fundamental understanding of matter, essential for various scientific applications and everyday life.