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Chemistry LibreTexts

1: The Process of Science

  • Page ID
    206521
    • 1.1: Welcome!
      Welcome! This course seeks to help you contextualize chemistry concepts through the lens of sustainability and climate change. The text will help to support your understanding of chemistry concepts along with topics of climate change.
    • 1.2: 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. From the structure of proteins and nucleic acids, to the design, synthesis and manufacture of drugs, chemistry allows you
    • 1.3: Chemicals Compose Ordinary Things
      Chemistry is the branch of science dealing with the structure, composition, properties, and the reactive characteristics of matter. Matter is anything that has mass and occupies space. Thus, chemistry is the study of literally everything around us – the liquids that we drink, the gasses we breathe, the composition of everything from the plastic case on your phone to the earth beneath your feet. Moreover, chemistry is the study of the transformation of matter.
    • 1.4: What is an Argument?
      In this course, lab reports are written using argument style called CER. Claim, Evidence, Reasoning
    • 1.5: The Process of Science
      In most textbooks, the scientific method is defined as the several steps generally starting with observations, followed by making a hypothesis, running an experiment and drawing a conclusion. This is the general form of a scientific method; however, there are so many pieces to the puzzle of running an experiment or understanding how something works.
    • 1.6: Hypothesis, Theories, and Laws
      Although all of us have taken science classes throughout the course of our study, many people have incorrect or misleading ideas about some of the most important and basic principles in science. We have all heard of hypotheses, theories, and laws, but what do they really mean? Before you read this section, think about what you have learned about these terms before. What do these terms mean to you? What do you read contradicts what you thought? What do you read supports what you thought?
    • 1.7: Classifying Matter According to Its Composition
      One useful way of organizing our understanding of matter is to think of a hierarchy that extends down from the most general and complex to the simplest and most fundamental. Matter can be classified into two broad categories: pure substances and mixtures. A pure substance is a form of matter that has a constant composition and properties that are constant throughout the sample. A material composed of two or more substances is a mixture.
    • 1.8: Energy
      Energy is a ubiquitous term we all use from a young age in a variety of contexts. We sometimes feel like we have no energy or we have a lot of excess energy. Many people now consume “energy drinks.” We think about conserving energy by turning off lights or taking stairs instead of an elevator. Energy is something we encounter daily. We recharge our phones, burn gasoline in cars, feel the heat of the sun, watch as trees sway in the wind, glance up to see if a rock is poised to fall or an icicle i
    • 1.9: Looking for Patterns- The Periodic Table
      Certain elemental properties become apparent in a survey of the periodic table as a whole. Every element can be classified as either a metal, a nonmetal, or a metalloid (or semi metal). A metal is a substance that is shiny, typically (but not always) silvery in color, and an excellent conductor of electricity and heat. Metals are also malleable (they can be beaten into thin sheets) and ductile (they can be drawn into thin wires).
    • 1.10: 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.
    • 1.11: 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.
    • 1.12: 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.
    • 1.13: 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. You should also note that these equations will often require you to use measurements with their units. Algebra skills become very important here!
    • 1.14: The Nuclear Atom
      While Dalton's Atomic Theory held up well, J. J. Thomson demonstrate that his theory was not the entire story. He suggested that the small, negatively charged particles making up the cathode ray were actually pieces of atoms. He called these pieces "corpuscles," although today we know them as electrons. Thanks to his clever experiments and careful reasoning, J. J. Thomson is credited with the discovery of the electron.
    • 1.15: The Properties of Protons, Neutrons, and Electrons
      The atom is composed of three subatomic particles including the proton, neutron, and electron.
    • 1.16: Elements- Defined by Their Number of Protons
      Scientists distinguish between different elements by counting the number of protons in the nucleus. Since an atom of one element can be distinguished from an atom of another element by the number of protons in its nucleus, scientists are always interested in this number, and how this number differs between different elements. The number of protons in an atom is called its atomic number (Z). This number is very important because it is unique for atoms of a given element.
    • 1.17: Ions
      As discussed in the previous section, the number of protons in an atom determines to which element an atom belongs.  If the number of protons changes (as you will in see in unit 2 can happen during nuclear reactions) the identity of the atom changes.  In a neutral atom, the number of protons and electrons are equal to each other.  However, the number of electrons in an atom can change.  If the number of electrons changes compared to the number in a neutral atom, the resulting particle is charged
    • 1.18: Isotopes - When the Number of Neutrons Varies
      All atoms of the same element have the same number of protons, but some may have different numbers of neutrons. For example, all carbon atoms have six protons, and most have six neutrons as well. But some carbon atoms have seven or eight neutrons instead of the usual six. Atoms of the same element that differ in their numbers of neutrons are called isotopes. Many isotopes occur naturally.
    • 1.19: Atomic Mass- The Average Mass of an Element’s Atoms
      In chemistry we very rarely deal with only one isotope of an element. We use a mixture of the isotopes of an element in chemical reactions and other aspects of chemistry, because all of the isotopes of an element react in the same manner. That means that we rarely need to worry about the mass of a specific isotope, but instead we need to know the average mass of the atoms of an element.