AP Biology homework helppp!?
Electrons exist only at fixed levels of potential energy. However, if an atom absorbs sufficient energy, a possible result is:
A an electron may move to an electron shell farther out from the nucleus
B an electron may move to an electron shell closer to the nucleus.
C the atom may become a radioactive isotope.
D the atom would become a positively charged ion, or cation.
E the atom would become a negatively charged ion, or anion.
What do the four most abundant elements in life-carbon, oxygen, hydrogen, and nitrogen- have in common?
A They're elements only produced by living cells.
B Each element exists only in one isotopic form
C They all have unpaired electrons in their valence shells
D They are equal in electronegativity
Which atom is the cation in in ammonium chloride salt?
Each element in unique and different from other elements because of its
A atomic weight
B atomic number
C mass number
D only A and B are correct
E A, B, C are correct