What property of an element does the atomic number represent?
a. the mass of the atom
b. the size of the atom
c. the number of protons in the atom
d. the number of neutrons in an atom

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

In the cathode ray tube experiment, j. j. thomson passed an electric current through different gases inside a cathode ray tube in the presence of an electric field. in which two ways did this experiment change scientists’ understanding of the atom?

Ahydrogen atom has 1 electron. how many bonds can hydrogen form? a) 1 b) 2 c) 3 d) 4 e) 5