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General Chemistry: Molecules and Compounds

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Termini in questo insieme (28)

  • What is the difference between an element and a compound?
    Elements are pure substances consisting of one type of atom, while compounds are substances formed when two or more elements chemically combine in fixed proportions.
  • What defines a mixture compared to a compound?
    In a mixture, elements or compounds can mix in any proportions. In a compound, elements combine in fixed, definite proportions.
  • What are the two broad types of chemical bonds?
    Chemical bonds are classified as ionic (transfer of electrons between metals and nonmetals) and covalent (sharing of electrons between nonmetals).
  • How do ionic bonds form?
    Ionic bonds form by the transfer of electrons from a metal atom to a nonmetal atom, creating oppositely charged ions that attract each other.
  • What is a lattice in ionic compounds?
    In the solid phase, ionic compounds form a lattice, a regular 3D array of alternating cations and anions.
  • What characterizes covalent bonds?
    Covalent bonds involve the sharing of electrons between two or more nonmetal atoms, forming molecules.
  • What information does a chemical formula provide?
    A chemical formula indicates the elements present and the relative number of atoms or ions of each in a compound.
  • What are the three types of chemical formulas?
    The three types are empirical formulas (relative atom ratios), molecular formulas (actual atom counts), and structural formulas (bond connectivity).
  • How does a structural formula differ from an empirical formula?
    A structural formula shows how atoms are bonded and the molecule's geometry, while an empirical formula only shows the simplest ratio of atoms.
  • What is the difference between atomic and molecular elements?
    Atomic elements exist as single atoms (e.g., Na, Ne), while molecular elements exist as molecules of bonded atoms (e.g., O2, N2).
  • What is the basic unit of an ionic compound?
    The basic unit of an ionic compound is the formula unit, the smallest electrically neutral collection of ions.
  • How do you name type one ionic compounds?
    Name the metal cation (with invariant charge) first, followed by the base name of the nonmetal anion with the suffix -ide.
  • How do you name type two ionic compounds?
    For metals with variable charges, specify the metal's charge with a Roman numeral in parentheses after the metal name.
  • What are polyatomic ions?
    Polyatomic ions are charged species composed of covalently bonded atoms acting as a single ion in ionic compounds.
  • How are oxyanions named when there are two ions in a series?
    The ion with more oxygen atoms ends with -ate, and the one with fewer ends with -ite.
  • What are hydrates in ionic compounds?
    Hydrates are ionic compounds that contain a specific number of water molecules associated with each formula unit.
  • How are molecular compounds named?
    Molecular compounds use prefixes to indicate the number of atoms of each element, with the element having the smaller group number named first.
  • What defines an acid in chemistry?
    Acids are molecular compounds that release hydrogen ions (H+) when dissolved in water.
  • How are binary acids named?
    Use the prefix hydro-, the base name of the nonmetal, add -ic, and then the word acid.
  • How are oxyacids named?
    If the polyatomic ion ends in -ate, change to -ic; if it ends in -ite, change to -ous, then add acid.
  • What is molar mass?
    Molar mass is the mass in grams of one mole of molecules or formula units, numerically equal to the formula mass in amu.
  • How can molar mass and Avogadro's number be used together?
    Molar mass converts mass to moles, and Avogadro's number converts moles to number of molecules or atoms.
  • What is the empirical formula?
    The empirical formula is the simplest whole-number ratio of atoms in a compound, determined from elemental analysis.
  • How do you find an empirical formula from percent composition?
    Convert percent to grams, grams to moles, then divide all mole values by the smallest mole value to get whole-number ratios.
  • How is the molecular formula related to the empirical formula?
    The molecular formula is a whole-number multiple of the empirical formula, determined using the compound's molar mass.
  • What is combustion analysis used for?
    Combustion analysis determines the elemental composition of organic compounds by burning a known mass and measuring product masses.
  • What are hydrocarbons?
    Hydrocarbons are organic compounds composed only of carbon and hydrogen, including alkanes, alkenes, and alkynes.
  • What is a functional group in organic chemistry?
    A functional group is a specific atom or group of atoms that imparts characteristic chemical properties to an organic compound.