Chemical element same atomic number, or number of protons. Nuclear scientists, however, define a pure element as one that consists of only one stable isotope. For example, a copper wire is 99.99% chemically pure if 99.99% of its atoms are copper, with 29 protons each. However it is not isotopically pure since ordinary copper consists of two stable isotopes, 69% Cu and 31% Cu, with different numbers of neutrons. However, a pure gold ingot would be both chemically and isotopically pure, since ordinary gold consists only of one isotope, Au. Atoms of chemically pure elements may bond to each other chemically in
CU convoys anti-submarine screens for CU convoys because the s of the British and Canadian Mid-Ocean Escort Force were not fast enough to maneuver with these convoys. Nine tankers departed Curaçao as convoy CU 1 on 20 March 1943 and arrived in Liverpool on 1 April. Additional sailings from Curaçao were CU 2 in June, CU 3 in July, CU 4 in September, and CU 6 in November. Convoy CU 5 was the first to originate in New York on 13 October 1943. Approximately three or four CU convoys sailed from New York each month from December 1943 through May 1945. Convoys