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General Chemistry: Atoms, Elements, and the Periodic Table

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Termini in questo insieme (21)

  • What defines a neutral atom in terms of protons and electrons?
    A neutral atom has an equal number of protons and electrons.
  • What are ions and how are they formed?
    Ions are charged particles formed when atoms lose or gain electrons during chemical changes.
  • What is a cation?
    A cation is a positively charged ion formed by losing electrons.
  • What is an anion?
    An anion is a negatively charged ion formed by gaining electrons.
  • How does the size of isotopes of the same element compare?
    Isotopes with more neutrons are generally larger than those with fewer neutrons.
  • What is the Periodic Law as stated by Mendeleev?
    When elements are arranged by increasing mass, certain sets of properties recur periodically.
  • How did Mendeleev organize the periodic table?
    He arranged elements in rows by increasing mass so that elements with similar properties fall in the same vertical columns.
  • What was significant about the gaps in Mendeleev's periodic table?
    They allowed him to predict the existence and properties of undiscovered elements.
  • How is the modern periodic table arranged differently from Mendeleev's?
    Elements are arranged by increasing atomic number rather than atomic mass.
  • What are the three main classifications of elements in the periodic table?
    Metals, nonmetals, and metalloids.
  • List common properties of metals.
    Good conductors of heat and electricity, malleable, ductile, shiny, and tend to lose electrons in chemical changes.
  • List common properties of nonmetals.
    Poor conductors, not malleable or ductile, tend to gain electrons in chemical changes, and have varied physical states.
  • What are metalloids and their key property?
    Elements along the zigzag line between metals and nonmetals with mixed properties, often semiconductors.
  • What are main-group elements and transition elements?
    Main-group elements have largely predictable properties based on position; transition elements have less predictable properties.
  • How many groups and periods are in the periodic table?
    There are 18 groups (vertical columns) and 7 periods (horizontal rows).
  • What are noble gases and their key characteristic?
    Group 18 elements that are mostly unreactive and chemically stable.
  • What are alkali metals and a notable property?
    Group 1 reactive metals that lose one electron and react violently with water.
  • What are alkaline earth metals and their reactivity?
    Group 2 metals that are fairly reactive but less so than alkali metals, typically lose two electrons.
  • What are halogens and their reactivity?
    Group 17 very reactive nonmetals that tend to gain one electron.
  • How do main-group metals and nonmetals form ions relative to noble gases?
    Main-group metals lose electrons to form cations with the same electron count as the nearest noble gas; nonmetals gain electrons to form anions similarly.
  • How is the charge of ions from main-group elements predicted?
    Cation charge equals the group number; anion charge equals group number minus eight.