139) The electrons in the outermost energy level of an atom are called
A) group electrons.
B) core electrons.
C) valence electrons.
D) orbital electrons.
140) Which of the halogens is a liquid at room temperature?
A) fluorine
B) chlorine
C) bromine
D) iodine
141) Which of the halogens is a solid at room temperature?
A) fluorine
B) chlorine
C) bromine
D) iodine
142) How does the periodic table substantiate atomic theory?
A) Both are theoretical and cannot support each other.
B) Groups in the periodic table have similar properties based on similar features of atomic structure,
namely, the same number of valence electrons per atom.
C) All elements in a given period of the periodic table have the same number of valence electrons.
D) Mendeleev declared consistency between the periodic table and atomic theory.