1. when scientists look at these examples, what do they know about the atoms? carbon-12 carbon-14

the number of neutrons in each atom is not the same
the atoms have different properties
one atom has more protons than the other
onl one of the examples is an isotope

2. what is common to all elements in the same group in the periodic table? *
they have the same number of neutrons
they are all nonmetals
they have the same number of outer electrons
their properties are very different