What is one way that creativity made up for limited technology for early biologists? a) scientists created unique experiments for exploring living organisms without killing them. b) scientists personally designed the custom equipment they needed for their experiments. c) scientists were able to use their imaginations rather than experiments to answer questions. d )scientists developed advanced mathematics to compensate for limited technology.

Drag each label to the correct location on the chart. classify each reaction as endothermic or exothermic.

1)each group 16 element has how many valence electrons? ( )4 ( )6 ( )8 ( )16 2)how many dots appear in the dot structure for calcium ion, ca2+? ( )zero ( )one ( )two ( )eight 3) which of the following atoms forms a cation to obtain an octet of outer shell electrons? ( )magnesium ( )oxygen ( )fluorine ( )helium 4) an al3+ ion contains 13 protons and 10 electrons. ( )true ( )false 5) valence and non-valence electrons are represented in lewis dot structures. ( )true ( )false

What does the symbol (–hfus) indicate in a phase change?