Matter, Measurement and the Scientific Method

Chemistry is the study of matter, which is anything that has mass and takes up space. Everything around you is matter, and it shows up in different states.

States of Matter

• ●Solid: fixed shape and fixed volume. Particles packed tight.
• ●Liquid: takes the shape of its container but keeps a fixed volume. Particles slide past each other.
• ●Gas: fills its whole container. Particles are spread far apart and move fast.

Physical vs Chemical Changes

• ●Physical change: the substance changes form but stays the same substance. Melting ice, ripping paper, dissolving sugar.
• ●Chemical change: a new substance forms. Burning wood, rusting iron, baking a cake. Signs include color change, gas bubbles, heat, or light.

SI Units and Significant Figures

• ●Length is measured in meters (m), mass in kilograms (kg) or grams (g), and time in seconds (s).
• ●Volume is often measured in liters (L), and temperature in Kelvin (K) or Celsius (C).
• ●Significant figures are the digits in a measurement you actually know for sure, plus one estimated digit. They tell you how precise a measurement is.