🧪 Introductory Chemistry Lecture 2

Energy

• Kinetic energy and heat energy are the same at the molecular level, but perceived differently in everyday life.

Mixtures

• Mixtures can be either homogeneous or heterogeneous.

Homogeneous Mixtures

• Composition is uniform throughout.
• Proportions of components remain constant.
• Example: Ethanol in water, Hand Sanitiser

Heterogeneous Mixtures

• Composition varies throughout.
• Can consist of different materials mixed together.

Elements

• Total known elements: 118
• Naturally occurring: 90
• Artificially created: 28