Unit 1 Study Guide Revision Sheet

1. 📌 Essentials

• Scientific notation expresses numbers as $A \times 10^n$, with $1 \leq A < 10$.
• Density formula: $\text{Density} = \frac{\text{Mass}}{\text{Volume}}$.
• Percent error measures measurement accuracy:frac{\text{Measured} - \text{Accepted}}{\text{Accepted}} \times 100$.
• Significant figures depend on measurement precision; rules vary for addition/subtraction multiplication/division.
• Elements are pure substances of one atom type; compounds are chemically bonded atoms in fixed ratios.
• Mixtures can be homogeneous (solutions) or heterogeneous (sand in water).
• Separation techniques include filtration, distillation, chromatography, and evaporation.
• Chemical changes produce new substances; physical changes do not.
• Temperature units: Celsius (°C) and Kelvin (K), with $K = °C + 273.15$.
• Phases of matter: solids (fixed particles), liquids (particles move), gases (dispersed particles).
• Heat transfer involves heat of fusion, vaporization, and specific heat capacity.