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GOB Chemistry Core Concepts

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  • What are the three states of matter?

    The three states of matter are solids, liquids, and gases.

  • How do physical and chemical properties differ?

    Physical properties can be observed without changing the substance, while chemical properties describe a substance's ability to undergo chemical changes.

  • What is the difference between a pure substance and a mixture?

    A pure substance has a fixed composition and properties, while a mixture contains two or more substances physically combined.

  • Define elements and compounds.

    Elements are pure substances made of one type of atom; compounds are pure substances made of two or more elements chemically combined.

  • What distinguishes homogeneous from heterogeneous mixtures?

    Homogeneous mixtures have uniform composition throughout; heterogeneous mixtures have visibly different parts.

  • List the changes of state between solids, liquids, and gases.

    Changes include freezing, melting, boiling, condensation, evaporation, sublimation, and deposition.

  • What is a physical change versus a chemical change?

    A physical change alters form without changing composition; a chemical change produces new substances.

  • How is specific heat calculated?

    Specific heat is calculated using \(q=mc\Delta T\), where q is heat, m is mass, c is specific heat, and \(\Delta\) T is temperature change.

  • What does a heating or cooling curve represent?

    It shows temperature changes and phase changes of a substance as heat is added or removed.

  • Name the main components of the Periodic Table.

    The Periodic Table is organized into periods, groups, metals, nonmetals, and metalloids.

  • What are common characteristics of metals?

    Metals are typically lustrous, malleable, ductile, and good conductors of heat and electricity.

  • What are common characteristics of nonmetals?

    Nonmetals are usually brittle when solid, poor conductors, and can be gases or solids at room temperature.

  • Describe metalloids and their properties.

    Metalloids have properties intermediate between metals and nonmetals and are semiconductors.

  • What is atomic theory?

    Atomic theory states that matter is made of atoms, which are the smallest units of elements retaining their properties.

  • Identify the parts of an atom and their charges.

    Atoms consist of protons (+), neutrons (neutral), and electrons (-).

  • How do you determine atomic number, mass number, and atomic mass?

    Atomic number = number of protons; mass number = protons + neutrons; atomic mass is the weighted average of isotopes.

  • What is electron configuration?

    Electron configuration describes the arrangement of electrons in an atom's shells and subshells.

  • What are shells, subshells, and orbitals?

    Shells are energy levels; subshells are divisions within shells (s, p, d, f); orbitals are regions where electrons are likely found.

  • What are the main trends in the Periodic Table?

    Trends include atomic size decreasing across periods, ionization energy increasing across periods, and metallic character decreasing across periods.

  • How does atomic size change across a period and down a group?

    Atomic size decreases across a period and increases down a group due to electron shielding and nuclear charge.

  • What is ionization energy?

    Ionization energy is the energy required to remove an electron from an atom in the gas phase.

  • How does metallic character vary in the Periodic Table?

    Metallic character decreases across a period and increases down a group.