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Atoms- Smallest Unit of Matter quiz #3

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  • What is the octet rule, and how does it relate to the stability and reactivity of atoms?
    The octet rule states that atoms are more stable and less reactive when their outermost (valence) electron shell is full, typically with eight electrons. Atoms with incomplete valence shells tend to be more reactive as they seek to fill or empty their outer shell.
  • What are the three subatomic particles that make up an atom, and where is each located?
    The three subatomic particles are protons and neutrons, which are found in the nucleus, and electrons, which orbit the nucleus in energy shells.
  • How is the atomic number of an element defined, and why is it important?
    The atomic number is defined as the total number of protons in the nucleus of an atom, and it determines the identity of the element.
  • What is the difference between mass number and atomic mass (atomic weight)?
    The mass number is the total number of protons and neutrons in the nucleus of a single atom, while atomic mass is the average mass of all atoms of an element.
  • Which six elements make up the majority of living organisms, and what mnemonic helps remember them?
    The six elements are carbon, hydrogen, nitrogen, oxygen, phosphorus, and sulfur, remembered by the mnemonic CHNOPS.
  • What is a valence electron, and why are valence electrons important in chemical reactivity?
    A valence electron is an electron in the outermost energy shell (valence shell) of an atom, and these electrons are important because they are involved in chemical bonding and determine reactivity.
  • How many electrons can the first and second energy shells of an atom hold?
    The first energy shell can hold up to 2 electrons, and the second energy shell can hold up to 8 electrons.
  • What does the octet rule state about the stability and reactivity of atoms?
    The octet rule states that atoms are more stable and less reactive when their outermost (valence) electron shell is full, typically with eight electrons.
  • What happens to the identity of an atom if the number of protons in its nucleus changes?
    If the number of protons changes, the atom becomes a different element because the atomic number, which defines the element, has changed.
  • What is the difference between bulk elements and trace elements in living organisms?
    Bulk elements, like CHNOPS, are found in large amounts and make up most of the mass of living organisms, while trace elements are required in very small amounts for life.