Ch.1 Chemistry in Our Lives: Foundations, Scientific Method, and Scientific Notation

Ch.1 Chemistry in Our Lives

What is Chemistry?

Chemistry is the study of matter, including its composition, structure, properties, and the changes it undergoes. It is often referred to as the "central science" because it connects and underpins other scientific disciplines such as biology, physics, environmental science, and health sciences.

• Matter: Anything that occupies space (has volume) and has mass.

• Chemistry: Investigates how substances interact, transform, and the energy changes involved.

• Interdisciplinary Links: Chemistry is foundational to fields like molecular biology, pharmacology, radiochemistry, anatomy, physiology, and materials science.

• Example: The study of the physics of rocks and the earth is called Geology.

• Example: The study of motor functions and responses of the Venus Fly Trap falls under Plant Sciences.

The Scientific Method

The scientific method is a systematic procedure used to answer questions, test ideas, and build scientific knowledge. It involves observation, hypothesis formation, experimentation, data collection, and peer review.

• Observation: Collecting information from primary sources, either quantitatively (e.g., body temperature) or qualitatively (e.g., patient looks flushed).

• Hypothesis: A proposed, testable explanation for an observation. Answers "what will happen?" and "why it will happen?"

• Theory: A testable and broad hypothesis supported by extensive evidence.

• Law: A testable phenomenon that is universally accepted as true by the scientific community.

• Falsifiability: Hypotheses and theories can be disproven, but not absolutely proven correct.

Steps of the Scientific Method:

1. Make an Observation

2. Formulate a Hypothesis & Make Prediction

3. Ask a Question

4. Collect & Interpret Data

5. Draw Conclusions

6. Design & Conduct Experiment

7. Peer Review & Publish

• Example: A patient has high blood pressure. The scientific method can be used to investigate if lowering sodium intake affects blood pressure.

Practice: Identifying observations and hypotheses:

• Observation: Nurse records patient's resting pulse as 32 beats per minute.

• Hypothesis: Drinking coffee at night keeps me awake.

Scientific Notation

Scientific notation is a method used to express very large or very small numbers in a concise, manageable form. It is commonly used in chemistry to simplify calculations and data representation.

• Format: $a \times 10^n$ where a is the coefficient (≥ 1 and < 10), 10 is the base, and n is the exponent (an integer).

• Coefficient: The value at the start, must be ≥ 1 and < 10.

• Base: Always 10.

• Exponent: Indicates how many places the decimal is moved; positive exponent makes the number larger, negative makes it smaller.

Examples:

• $6.88 \times 10^{-12}$ (very small number)

• $7.17 \times 10^{5}$ (very large number)

Converting Scientific Notation to Standard Notation:

• Positive exponent: Move decimal to the right (number gets larger).

• Negative exponent: Move decimal to the left (number gets smaller).

Converting Standard Notation to Scientific Notation:

• Adjust the coefficient to be between 1 and 10.

• Increase coefficient → decrease exponent.

• Decrease coefficient → increase exponent.

Practice: Convert 377,000 to scientific notation: $3.77 \times 10^{5}$

Correct Scientific Notation: $5.220 \times 10^{3}$

Additional info: Scientific notation is essential for expressing measurements in chemistry, such as concentrations, atomic masses, and reaction rates.