Specify the number of protons, neutrons, and electrons in the neutral atom copper-64.
Enter your answers as integers separated by commas.
The ion S2− has _____ protons and _____ electrons.
Enter your answers as integers separated by a comma.
What isotope has 17 protons and 18 neutrons?
Enter the name of the element followed by a hyphen and the mass number (e.g., uranium-234).
Which element does X represent in the following expression: 5525X?
Enter the chemical symbol of the element.