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General Chemistry: Matter and Energy

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Termini in questo insieme (29)

  • What is energy?

    Energy is the capacity for performing work.

  • Name the three major categories of energy.

    Potential energy (PE), kinetic energy (KE), and thermal energy (heat).

  • What is potential energy (PE)?

    Energy an object has due to its position or arrangement of parts, such as in a gravitational field.

  • What is kinetic energy (KE)?

    Energy associated with motion, proportional to mass and the square of velocity: \(KE=\frac{1}{2}mv^2\).

  • State the law of conservation of energy.

    Energy can neither be created nor destroyed; it only transfers or transforms.

  • What is thermal energy?

    Sum of microscopic kinetic energy of particles in matter; related to temperature.

  • What are the SI and traditional units of energy?

    SI unit: Joule (J); traditional unit: calorie (cal); 1 cal = 4.184 J exactly.

  • How do you convert Celsius to Kelvin?

    \(T(K)=T(^\circ C)+273.15\)

  • Define matter.

    Matter is anything that has mass and volume.

  • What is the difference between heterogeneous and homogeneous mixtures?

    Heterogeneous mixtures have visible boundaries and varying composition; homogeneous mixtures (solutions) have uniform composition throughout.

  • What are pure substances?

    Substances consisting of a single type of chemical, either elements or compounds.

  • What distinguishes elements from compounds?

    Elements cannot be broken down by chemical means; compounds can be broken into two or more elements.

  • What are physical properties?

    Properties a substance has by itself without interaction with other substances.

  • What are the three physical states of matter?

    Solid, liquid, and gas.

  • Describe the gas phase of matter.

    Particles have high thermal energy and make little contact with each other.

  • Describe the liquid phase of matter.

    Particles have enough thermal energy to move around but remain close.

  • Describe the solid phase of matter.

    Particles are fixed in a crystal lattice but vibrate around equilibrium positions.

  • What is a physical change?

    A change involving only one substance without chemical interaction, usually reversible (e.g., phase changes).

  • What is a chemical property?

    A property observed when a substance interacts or transforms into other substances.

  • What is a chemical change?

    A change involving interaction between substances, often irreversible, producing new substances.

  • What is specific heat (SH)?

    The proportional constant relating heat added to temperature change: \(Heat=mass \times \Delta T \times SH\).

  • What is an endothermic process?

    Heat flows into the system; heat is positive.

  • What is an exothermic process?

    Heat flows out of the system; heat is negative.

  • What are the three subatomic particles in an atom?

    Electrons (negative charge), protons (positive charge), and neutrons (neutral).

  • What determines the chemical nature of an atom?

    The number of protons and electrons; neutrons do not affect chemical properties.

  • What is the atomic number (Z)?

    The number of protons in an atom.

  • What is the mass number (A)?

    The total number of protons and neutrons in an atom.

  • What are isotopes?

    Atoms of the same element with different numbers of neutrons.

  • State Coulomb's law in atomic context.

    Opposite charges attract; like charges repel.