Chapter 1 Review: Chemistry in Our Lives – Scientific Method and Scientific Notation

1.2 Scientific Method

The Scientific Method: How Chemists Think

The scientific method is a systematic approach used by scientists, including chemists, to investigate phenomena, acquire new knowledge, or correct and integrate previous knowledge. It involves a logical progression of steps that ensure findings are reliable and reproducible.

• Observation: Gathering information through the senses or instruments.

• Hypothesis: Formulating a tentative explanation or prediction based on observations.

• Experiment: Testing the hypothesis through controlled procedures.

• Theory: Developing a well-substantiated explanation based on repeated experiments and observations.

Example: The development of atomic models began with observations and hypotheses about matter, followed by experiments that led to modern atomic theory.

Additional info: The scientific method is iterative; theories may be revised or replaced as new evidence emerges.

1.3 Scientific Notation

Using Large and Small Numbers

Chemistry often requires working with very large or very small numbers. Scientific notation is a convenient way to express these values, making calculations easier and reducing errors.

• Numbers are written as the product of a number between 1 and 10 and a power of ten.

• Format: $a \times 10^n$ where a is a number between 1 and 10, and n is an integer.

• Positive exponents indicate large numbers; negative exponents indicate small numbers.

Example 1: The U.S. population in 2013 was approximately 315,000,000 people. In scientific notation:

• $315,000,000 = 3.15 \times 10^8$

Example 2: The radius of a carbon atom is approximately 0.000000000070 m. In scientific notation:

• $0.000000000070 = 7.0 \times 10^{-11}$ m

Additional info: Scientific notation is essential for expressing measurements in chemistry, such as atomic radii, Avogadro's number, and concentrations.