Matter is all around us, with unique properties that define its behavior. In this section, we'll dive into the physical and chemical properties of matter, exploring how substances interact and change. We'll also look at how matter is classified and the different states it can exist in.
We'll examine intensive and extensive properties, which help us understand and identify substances. By the end, you'll have a solid grasp on the fundamental characteristics of matter and how they relate to the broader study of chemistry.
Differentiate between physical and chemical properties of matter
Physical properties
- Characteristics that can be observed or measured without changing the composition of the substance
- Examples include color, density, melting point, and boiling point
- Other examples are solubility, electrical conductivity, and malleability
- Changes in physical properties do not result in the formation of a new substance
Chemical properties
- Describe how a substance interacts with other substances to form new substances
- Examples include reactivity, flammability, and corrosiveness
- Other examples are oxidation, combustion, and decomposition
- Changes in chemical properties involve the formation of one or more new substances
Classify matter as pure substances or mixtures based on their composition
Pure substances
- Have a fixed composition and cannot be separated into simpler substances by physical means
- Can be either elements or compounds
- Elements are composed of only one type of atom and cannot be broken down into simpler substances by chemical means (hydrogen, oxygen, carbon)
- Compounds are composed of two or more elements chemically combined in a fixed ratio (water (H2O), carbon dioxide (CO2), sodium chloride (NaCl))
Mixtures
- Composed of two or more substances that are not chemically combined and can be separated by physical means
- Can be either homogeneous or heterogeneous
- Homogeneous mixtures have a uniform composition throughout (air, salt water, brass)
- Also called solutions
- Heterogeneous mixtures have a non-uniform composition (sand and water, oil and vinegar, concrete)
- Homogeneous mixtures have a uniform composition throughout (air, salt water, brass)
Identify intensive and extensive properties of matter
Intensive properties
- Independent of the amount of substance present
- Examples include density, melting point, boiling point, and specific heat
- Can be used to identify a substance
Extensive properties
- Depend on the amount of substance present
- Examples include mass, volume, and total heat capacity
- Cannot be used to identify a substance
- The ratio of two extensive properties is an intensive property (density is the ratio of mass to volume)
Describe the states of matter and their characteristics
Solid state
- Particles are closely packed and have fixed positions
- Results in a definite shape and volume
- Examples include ice, metals, and wood
Liquid state
- Particles are close together but can move relative to each other
- Results in a definite volume but no fixed shape
- Examples include water, oil, and mercury
Gaseous state
- Particles are far apart and move randomly
- Results in no definite shape or volume
- Examples include air, helium, and carbon dioxide
Changes in states of matter
- Changes in temperature and pressure can cause matter to change states
- Melting: solid to liquid
- Freezing: liquid to solid
- Vaporization: liquid to gas
- Condensation: gas to liquid
- Sublimation is the direct transition from solid to gas
- Deposition is the direct transition from gas to solid, both without passing through the liquid state