Elements are arranged in groups by similar atomic structure on the periodic table. this allows for an elements properties to be predicted based on general periodic trends. one of these trends, atomic radius, increase down a group and to the left along a period and can be defined as

a). one-half the distance between the nuclei of two atoms

b). the distance between the nuclei of two atoms

c). one-half the diameter of an atom

d). the diameter of an atom

If the sun were to become a black hole, what would happen to earth? it is impossible to know the results. it would be sucked in very rapidly. it would continue in the same orbit. it would be sucked in very slowly. 3. which type of radiation us map the galaxy? visible light infrared 21 cm radio waves ultraviolet 4. henrietta leavitt found that the brighter appearing cepheids always had longer periods of light variation. this is an expression of what? period-luminosity relation luminosity function hertzsprung-russell diagram mass-luminosity relation 5. what is the surface or boundary of a black hole called? quasar active galaxy event horizon seyfert point 6. edwin hubble's discovery of a cepheid variable in the andromeda nebula led him to conclude that the nebula was what? a distant galaxy composed of hydrogen a supernova remnant the birthplace of stars 7. earth is near the center of the milky way galaxy. true false 8. how long does it take the sun to revolve around the center of the galaxy? two hundred thousand years two hundred million years two hundred years two hundred billion years