On the periodic table, hydrogen and helium are the only two elements in the first row, or period, which reflects that they only have electrons in their first shell. Hydrogen and helium are the only two elements that have electrons exclusively in the 1 s 1s 1s orbital in their neutral, non-charged, state.
Tantalum is the 73rd element in the periodic table with an atomic mass equal to 180.95 g/mol. To determine the number of moles present in the given mass of tantalum above, we simply divide the mass by the atomic mass.
number of moles = (0.0073 kg)(1000 g/ 1kg) ÷ (180.95 g/mol)
number of moles = 0.0403 moles
Therefore, there is approximately 0.0403 moles of tantalum in 0.0073 kg.
Answer:
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Answer:
6400 molecules / cm^3
Explanation:
10.6*10^-16 mol/L * 6.022*10^23 molecules/mol * 1 L / 1000 cm^3 * 1 / 100 L = 6400 molecules / cm^3
