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Chemistry LibreTexts

1: Unit 1

  • Page ID
    492109
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    • 1.1: The Scope of Chemistry
      Chemistry is the study of matter and the ways in which different forms of matter combine with each other. You study chemistry because it helps you to understand the world around you. Everything you touch or taste or smell is a chemical, and the interactions of these chemicals with each other define our universe. Chemistry forms the fundamental basis for biology and medicine.
    • 1.2: The Scientific Method - How Chemists Think
      Science is a process of knowing about the natural universe through observation and experiment. Scientists go through a rigorous process to determine new knowledge about the universe; this process is generally referred to as the scientific method. Science is broken down into various fields, including chemistry, and is both qualitative and quantitative.
    • 1.3: Hypothesis, Theories, and Laws
      Although many have taken science classes throughout the course of their studies, people often have incorrect or misleading ideas about some of the most important and basic principles in science. Most students have heard of hypotheses, theories, and laws, but what do these terms really mean? Prior to reading this section, consider what you have learned about these terms before. What do these terms mean to you? What do you read that contradicts or supports what you thought?
    • 1.4: Taking Measurements
      Chemists measure the properties of matter and express these measurements as quantities. A quantity is an amount of something and consists of a number and a unit. The number tells us how many (or how much), and the unit tells us what the scale of measurement is. For example, when a distance is reported as “5 kilometers,” we know that the quantity has been expressed in units of kilometers and that the number of kilometers is 5.
    • 1.5: Scientific Notation - Writing Large and Small Numbers
      Chemists often work with numbers that are exceedingly large or small. For example, entering the mass in grams of a hydrogen atom into a calculator requires a display with at least 24 decimal places. A system called scientific notation avoids much of the tedium and awkwardness of manipulating numbers with large or small magnitudes.
    • 1.6: Significant Figures - Writing Numbers to Reflect Precision
      Uncertainty exists in all measurements. The degree of uncertainty is affected in part by the quality of the measuring tool. Significant figures give an indication of the certainty of a measurement. Rules allow decisions to be made about how many digits to use in any given situation.
    • 1.7: Significant Figures in Calculations
      To round a number, first decide how many significant figures the number should have. Once you know that, round to that many digits, starting from the left. If the number immediately to the right of the last significant digit is less than 5, it is dropped and the value of the last significant digit remains the same. If the number immediately to the right of the last significant digit is greater than or equal to 5, the last significant digit is increased by 1.
    • 1.8: The Basic Units of Measurement
      Metric prefixes derive from Latin or Greek terms. The prefixes are used to make the units manageable. The SI system is based on multiples of ten. There are seven basic units in the SI system. Five of these units are commonly used in chemistry.
    • 1.9: Problem Solving and Unit Conversions
      During your studies of chemistry (and physics also), you will note that mathematical equations are used in a number of different applications. Many of these equations have a number of different variables with which you will need to work. Note also that these equations will often require the use of measurements with their units. Algebra skills become very important here!
    • 1.10: Solving Multi-step Conversion Problems
      Sometimes you will have to perform more than one conversion to obtain the desired unit.
    • 1.11: Units Raised to a Power
      Conversion factors for area and volume can also be produced by the dimensional analysis method. Remember that if a quantity is raised to a power of 10, both the number and the unit must be raised to the same power of 10.
    • 1.12: Density
      Density is a physical property found by dividing the mass of an object by its volume. Regardless of the sample size, density is always constant.
    • 1.13: Temperature - Random Motion of Molecules and Atoms
      Three different scales are commonly used to measure temperature: Fahrenheit (expressed as °F), Celsius (°C), and Kelvin (K).
    • 1.E: Measurement and Problem Solving (Exercises)
      Exercises for Chapter 2 of Tro's Introductory Chemistry textmap.


    1: Unit 1 is shared under a not declared license and was authored, remixed, and/or curated by LibreTexts.

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