A) their volumes are always equal. B) the ratio of their masses is always the same. C) each element contributes an equal number of atoms. D) their masses are always equal.
A) There is a dense, positively charged mass in the center of an atom. B) Negative and positive charges are spread evenly throughout an atom. C) Alpha particles have a positive charge. D) Gold is not as dense as previously thought.
A) concentrated at multiple sites in an atom. B) located in the space outside the nucleus. C) concentrated in the center of an atom. D) spread evenly throughout an atom.
A) neutron B) proton C) electron
A) Protons, neutrons, and electrons all have about the same mass. B) An electron has far less mass then either a proton or a neutron. C) Unlike protons or neutrons, electrons have no mass. D) Neutrons have no charge and no mass.
A) the number of neutrons B) the number of protons C) the charge on the electrons D) the mass of the neutron
A) isotope B) atomic number C) mass number D) charge
A) isotope number from atomic number B) atomic number from mass number C) mass number from atomic number D) atomic number from electron number
A) like popcorn in a popper. B) like planets orbiting the sun. C) like balls rolling down a hill. D) like beach balls on water waves.
A) the precise location of electrons in an atom B) the number of electrons in an atom C) the most likely locations of electrons in an atom D) the mass of the electrons in the atom
A) they form negative ions B) they are located in the left-most column of the periodic table C) they are usually gases D) the are extremely nonreactive
A) amount of a substance B) volume of a substance C) mass of a substance D) electric charge of a substance
A) isotope number B) atomic number C) mass number D) atomic mass unit
A) how tightly atoms are packed in the element B) its atomic mass C) the ratio of protons to neutrons in atoms of the element D) the number of valence electrons in atoms of the element
A) They are isotopes of oxygen B) They have the same mass number C) their masses are identical D) they do not have the same number of protons
A) group to group B) column to column C) row to row D) element to element
A) helium, carbon, gold B) iodine, iron, nickel C) sodium, chromium, copper D) phosphorus, nitrogen, oxygen
A) the immediate acceptance by other scientists. B) the discovery of elements with predicted properties. C) the discovery of the nucleus. D) the discovery of subatomic particles.
A) none B) four C) two D) three
A) decreases B) increases C) stays the same D) increases then decreases
A) neutron B) chlorine-35 atom C) proton D) carbon-12 atom
A) -1 B) -2 C) +1 D) 0
A) 1/1840 B) 1 C) 1/18 D) 0
A) chemical properties B) mass C) period D) number of neutrons
A) changing from one period to another B) losing or gaining electrons C) losing or gaining protons D) changing from lithium into fluorine
A) one-twelfth the mass of a carbon-12 atom B) one-half the mass of a hydrogen atom C) one-fifteenth the mass of a nitrogen-15 atom D) one-fourth the mass of a lithium atom
A) They exist as single elements rather than molecules B) they are rare in nature C) they are highly reactive D) they can form compounds with bright colors
A) are extremely hard B) do not form compounds C) have large atomic masses but small atomic numbers D) can conduct electric current only under certain conditions
A) in the middle B) on the left C) on the bottom D) on the right
A) one mole of a pure substance B) one gram of a pure substance C) one liter of a pure substance D) one kilogram of a pure substance.
A) 80 B) 79 C) 35 D) 172
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