Mixtures and Compounds: Separating Techniques

Mixtures

• A mixture is a combination of two or more substances that are not chemically bonded and can be separated by physical means.
• Mixtures can be homogeneous (uniform composition) or heterogeneous (non-uniform composition).
• Methods for separating mixtures include:

  Filtration

  • Separates solids from liquids in a heterogeneous mixture

  Evaporation

  • Separates a dissolved solid from a solution by heating

  Distillation

  • Separates substances based on their boiling points

  Chromatography

  • Separates substances based on their movement through a medium

Compounds

• A compound is a substance formed when two or more elements are chemically bonded together.
• Characteristics of compounds:
  • Have fixed compositions
  • Properties differ from those of the individual elements
  • Can only be separated into their elements by chemical means

Types of Bonds in Compounds

Ionic Bonds

• Formed when atoms give or take electrons to stick together
• Example: Salt (NaCl), where sodium gives an electron to chlorine

Covalent Bonds

• Formed when atoms share electrons to stick together
• Example: Water (H2O), where oxygen shares electrons with hydrogen

Metallic Bonds

• Formed when metals share their electrons with many other atoms, creating a shared pool of electrons
• Example: Copper (Cu), which is bendy and good at carrying electricity

Hydrogen Bonds

• A weak bond formed when a hydrogen atom gets close to a negative part of another molecule
• Example: Water molecules sticking to each other, making water liquid at room temperature