교과서 질문The subscript giving the atomic number of an atom is often left off when writing an isotope symbol. For example, 6 often written simply as 13C. Why is this allowed?1032views
교과서 질문Give the names and symbols for the following elements: (a) An element with atomic number 6 (b) An element with 18 protons in its nucleus (c) An element with 23 electrons1273views1rank
미해결 질문Which element is placed in the same period as ruthenium but has a higher atomic number than it?988views
미해결 질문After Mendeleev organized the periodic table by atomic weight, he noticed a pattern of ....?1043views