CBr4 electronegativity difference

How is the composition of a meteorite relevant to finding out the composition of earth's core?

What does the process of natural selection involve

The alkali metals (group 1) consist of lithium (3), sodium (11), potassium (19), rubidium (37), cesium (55), and francium (87). they are soft, metallic solids with low densities and low melting points. based on the data shown in figure 1, how many valence electrons do alkali metals share?