Science Class on Mixtures and Changes in Matter

Mixtures

• Iron ore is classified as heterogeneous.
• Quartz is a homogeneous mixture.
• Granite is considered heterogeneous.
• Energy drinks are homogeneous mixtures.
• Oil and vinegar salad dressing is heterogenous.

Changes in Matter

• Melting ice represents a physical change.
• Burning paper is a chemical change.
• Rusting metal is a chemical change.
• Increasing gas pressure is a physical change.
• Evaporating liquid is a physical change.
• Digesting food is a chemical change.

Types of Changes

• Chemical changes rearrange atoms, forming new substances with different properties.
• Physical changes alter properties such as state or shape, but the substance's composition remains unchanged.

Definitions

• Homogeneous mixture: Uniform composition throughout.
• Heterogeneous mixture: Non-uniform composition; components are not evenly distributed.
• Mass: Measure of the amount of matter in an object.
• Matter: Anything with mass and volume.
• Atom: Basic unit of matter.
• Compound: Substance made of two or more different elements bonded chemically.
• Physical property: Observed without changing the substance.
• Chemical property: Describes the ability to transform into different substances.

Energy in Changes

• Energy is absorbed or released during both chemical and physical changes but is not created or destroyed; it changes forms or location.

Periodic Table

• A horizontal row of elements is called a period.
• Metals are good conductors of heat and electricity.
• Non-metals conduct poorly.
• A vertical column of elements is known as a family or group.
• Elements in the same group exhibit similar chemical properties.

Malleability

• Malleability refers to the ability of a substance to deform under pressure, often observed when hammered or rolled.

Laboratory Safety

• Always wear goggles in the lab for eye protection.
• Use close-toed shoes for foot safety.
• Wear an apron to protect clothing from spills.
• Use rubber gloves when handling corrosive chemicals.
• When mixing acids and water, always add acid first.

Fire Safety

• Fire extinguishers should be used by pulling the pin, aiming, squeezing, and sweeping across the fire.

Hazardous Substances

• Corrosive substances gradually eat away materials.
• Toxic substances are poisonous.
• Irritants can cause rashes or allergic reactions.
• Carcinogenic substances are linked to cancer risks.
• Flammability indicates the ability to burn.
• Radioactivity refers to the emission of particles or high-energy waves.

Hazard Identification

• Hazard diamonds indicate dangers:
  • Red (top): Flammable
  • Blue (left): Health hazard
  • White (bottom): Special information
  • Yellow (right): Reactivity hazard
• Numbers on hazard diamonds signify the level of hazard, ranging from 0 (no hazard) to 4 (deadly hazard).