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GOB Chemistry: Elements and the Periodic Table

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Termini in questo insieme (21)

  • What is chemistry primarily concerned with?
    Chemistry primarily looks at the properties of, and the interactions between, various substances.
  • What are elements?
    Elements are pure substances from which all other things are built and cannot be broken down into simpler substances.
  • How are chemical symbols for elements written?
    Chemical symbols consist of one or two letters, always starting with a capital letter.
  • What is the organization principle of the periodic table?
    The periodic table organizes 118 elements into groups with similar properties in vertical columns and periods as horizontal rows, ordered by increasing atomic mass.
  • What do group numbers in the periodic table represent?
    Group numbers relate to the number of valence electrons in representative elements and are written at the top of each vertical column.
  • What do period numbers in the periodic table represent?
    Period numbers relate to the number of electron layers surrounding the nuclei of elements.
  • What is the difference between representative and transition elements?
    Representative elements are in Groups 1A–8A (or 1-2, 13-18), while transition elements are in Groups 3B–8B, 1B-2B (or 3-12).
  • Where are metals, nonmetals, and metalloids located on the periodic table?
    Metals are on the left (except hydrogen), nonmetals on the right, and metalloids lie along the zigzag line separating metals and nonmetals.
  • List key characteristics of metals.
    Metals are shiny, ductile, conduct heat and electricity well, and are mostly solids except mercury.
  • List key characteristics of nonmetals.
    Nonmetals are dull, brittle, poor conductors (good insulators), and have low densities and melting points.
  • What are metalloids and their properties?
    Metalloids have properties between metals and nonmetals, are better conductors than nonmetals but worse than metals, and are used as semiconductors.
  • Which elements are in Group 1A (alkali metals)?
    Group 1A includes lithium (Li), sodium (Na), potassium (K), rubidium (Rb), cesium (Cs), and francium (Fr), and excludes hydrogen.
  • What are the characteristics of alkali metals?
    Alkali metals are highly reactive with water and are found in Group 1A.
  • Which elements are in Group 2A (alkaline earth metals)?
    Group 2A includes beryllium (Be), magnesium (Mg), calcium (Ca), strontium (Sr), barium (Ba), and radium (Ra).
  • What is a notable use of strontium (Sr)?
    Strontium provides the red color in fireworks.
  • Which elements are in Group 7A (halogens)?
    Group 7A includes fluorine (F), chlorine (Cl), bromine (Br), iodine (I), astatine (At), and tennessine (Ts).
  • What are the properties of halogens?
    Halogens are highly reactive and form compounds with most elements.
  • Which elements are in Group 8A (noble gases)?
    Group 8A includes helium (He), neon (Ne), argon (Ar), krypton (Kr), xenon (Xe), radon (Rn), and oganesson (Og).
  • What are the properties of noble gases?
    Noble gases are unreactive and seldom form compounds with other elements.
  • Which four elements make up 96% of human body mass?
    Oxygen, carbon, hydrogen, and nitrogen make up 96% of the human body mass.
  • What role do macrominerals play in the human body?
    Macrominerals like Ca, P, K, Cl, S, Na, and Mg are involved in bone formation, heart and muscle function, nerve impulses, and cellular metabolism.