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General Chemistry: Matter, Measurement, and Problem Solving

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  • What is chemistry?

    Chemistry is the study of matter, atoms and molecules, and how substances behave and change.

  • Define an atom.

    An atom is the basic building block of matter and the smallest unit of an element.

  • What is a molecule?

    A molecule consists of two or more atoms chemically bonded together.

  • List the steps of the scientific method.

    1. Observation 2. Hypothesis 3. Experimentation 4. Laws and theories

  • What does a scientific law describe?

    A scientific law describes what happens in nature, often as a concise statement or mathematical expression.

  • What does a scientific theory explain?

    A scientific theory explains why or how something happens based on evidence.

  • Describe the characteristics of a solid state of matter.

    Solids have fixed shape and volume with particles tightly packed in an organized structure.

  • How do liquids differ from solids?

    Liquids have fixed volume but take the shape of their container; particles move around each other.

  • What are the properties of gases?

    Gases have no fixed shape or volume; particles are far apart and move freely.

  • What is the difference between crystalline and amorphous solids?

    Crystalline solids have an organized repeating structure; amorphous solids have a random, non-repeating structure.

  • Define pure substance.

    A pure substance has a fixed composition and consists of only one type of substance.

  • What distinguishes an element from a compound?

    An element cannot be chemically broken down; a compound consists of two or more elements chemically bonded.

  • What is a mixture?

    A mixture is a physical combination of two or more substances without chemical bonding.

  • Differentiate homogeneous and heterogeneous mixtures.

    Homogeneous mixtures are uniform throughout; heterogeneous mixtures are non-uniform.

  • Name three methods to separate mixtures.

    Filtration, distillation, and decanting are common methods to separate mixtures.

  • What defines a physical change?

    A physical change alters appearance or state but does not change composition.

  • What defines a chemical change?

    A chemical change changes composition and creates new substances.

  • Give examples of physical and chemical properties.

    Physical properties: color, density, melting point. Chemical properties: flammability, acidity.

  • What is energy and its main types?

    Energy is the capacity to do work. Main types: kinetic (motion) and potential (stored) energy.

  • State the law of conservation of energy.

    Energy cannot be created or destroyed, only transformed.

  • What are the SI units for length, mass, time, and temperature?

    Length: meter (m), Mass: kilogram (kg), Time: second (s), Temperature: kelvin (K).

  • What is the Kelvin temperature scale?

    The Kelvin scale is an absolute temperature scale starting at absolute zero (0 K).

  • How is density calculated?

    Density = mass divided by volume, \(\frac{mass}{volume}\).

  • Differentiate intensive and extensive properties.

    Intensive properties do not depend on amount (e.g., density). Extensive properties depend on amount (e.g., mass).

  • What do significant figures indicate?

    Significant figures indicate the precision of a measurement.

  • Rules for significant figures in multiplication/division?

    Result has the same number of significant figures as the value with the fewest significant figures.

  • Rules for significant figures in addition/subtraction?

    Result has the same number of decimal places as the value with the fewest decimal places.

  • Define accuracy and precision.

    Accuracy is closeness to the true value; precision is consistency among measurements.

  • What is dimensional analysis used for?

    Dimensional analysis is used for unit conversions using conversion factors and unit cancellation.