1.1: science basics

introductory terms

• chemistry: the study of the properties and behavior of matter
    * central to our fundamental understanding of many science-related fields

scientific laws and theories

• law: a statement about what happens in nature that seems to always be true
    * allows predictions about how a natural system will work or behave
    * does not explain how a process takes place
• theory: an explanation for a natural phenomenon
    * eg. big bang theory (broad explanation)

observations and types of data

• quantitative measurements
    * involve numbers and units
    * objective and precise (eg. -12°C, 100kg, 14cm)
    * must include units
• qualitative measurements
    * descriptions
    * subjective and imprecise (eg. red, hot, bubbly, heavy)
    * perception-based
• observation: information gathered directly through the five senses
• inference: a logical explanation for an observation based on context, prior knowledge, and experience
• eg. observation—the fire alarm is oging off
• possible inferences: the building is on fire, there is a fire drill, someone pulled the fire alarm

units of measurement—SI units

• based on the Système International d’Unités (International System of Units)
• there is a different base unit for each quality (eg. length, weight)

SI base units

• mass and length
    * mass: the amount of matter (stuff) in an object—not weight!
    * length: a measure of distance
• volume
    * not a base unit in the SI sy31dx2stem
    * derived unit from length; most commonly used metric units are liters (L) and milliliters (mL)
• temperature
    * temperature: the measure of the average kinetic energy of the particles that make up an object
    * the Kelvin and Celsius temperature scales are used in science, not Fahrenheit
    * heat flow at a higher rate = higher temperature and vise-versa
    * the Celsius scale is based on the physical properties of water
• density
    * derived unit from mass/volume (D=M/V)
    * commonly used units: g/mL or g/cm^3