Group 17 elements (for example, chlorine) in the periodic table are known as alkali metals.
• halogens.
noble gases.
transition metals.

Scientists often deal with numbers that are either very large or very small. for example, the radius of the sun is approximately 696,000 kilometers, while bacterial cells are as small as 1.9 × 10-4 millimeters. express each of these numbers in an alternate form.