look at the two question marks between zinc (zn) and arsenic (as). at the time, no elements were known with atomic weights between 65.2 and 75. but mendeleev predicted that two elements must exist with atomic weights in this range.
what led mendeleev to predict that two undiscovered elements existed in that range?

Why is the structure of molecule important to its function?

Rocks, as they are compressed, begin forming mountains above the earth's surface when two continental plates converge. the continental crust increases in depth as the mountains grow above. the himalayan mountains formed at a convergent plate boundary in this manner. the rocks are smashed together causing them to due to the intense heat and pressure from the colliding plates and eventually forming rock. a) melt; igneous b) layer; sedimentary c) recrystallize; metamorphic d) melt into the earth's interior; metamorphic

1) which of the following is the best example of a physical change? a) sugar dissolving in tea b) firefly glowing 2) in the combustion of ethane, what is/are the reactants? c2h6 + o2 ==> co2 + h2o a) c2h6 and o2 b) co2 and c2h6