Input interpretation
niobium(IV) telluride | elemental composition
Result
Find the elemental composition for niobium(IV) telluride in terms of the atom and mass percents: atom percent = N_i/N_atoms × 100% mass percent = (N_im_i)/m × 100% Plan: • Write the chemical formula and gather atomic masses from the periodic table. • Determine values for N_i, m_i, N_atoms and m using these items. • Finally, compute the percents and check the results. Write the chemical formula: NbTe_2 Use the chemical formula, NbTe_2, to count the number of atoms, N_i, for each element and find the total number of atoms, N_atoms: | number of atoms Nb (niobium) | 1 Te (tellurium) | 2 N_atoms = 1 + 2 = 3 Divide each N_i by N_atoms to calculate atom fractions. Then use the property that atom fractions must sum to one to check the work: | number of atoms | atom fraction Nb (niobium) | 1 | 1/3 Te (tellurium) | 2 | 2/3 Check: 1/3 + 2/3 = 1 Compute atom percents using the atom fractions: | number of atoms | atom percent Nb (niobium) | 1 | 1/3 × 100% = 33.3% Te (tellurium) | 2 | 2/3 × 100% = 66.7% Look up the atomic mass, m_i, in unified atomic mass units, u, for each element in the periodic table: | number of atoms | atom percent | atomic mass/u Nb (niobium) | 1 | 33.3% | 92.90637 Te (tellurium) | 2 | 66.7% | 127.60 Multiply N_i by m_i to compute the mass for each element. Then sum those values to compute the molecular mass, m: | number of atoms | atom percent | atomic mass/u | mass/u Nb (niobium) | 1 | 33.3% | 92.90637 | 1 × 92.90637 = 92.90637 Te (tellurium) | 2 | 66.7% | 127.60 | 2 × 127.60 = 255.20 m = 92.90637 u + 255.20 u = 348.10637 u Divide the mass for each element by m to calculate mass fractions. Then use the property that mass fractions must sum to one to check the work: | number of atoms | atom percent | mass fraction Nb (niobium) | 1 | 33.3% | 92.90637/348.10637 Te (tellurium) | 2 | 66.7% | 255.20/348.10637 Check: 92.90637/348.10637 + 255.20/348.10637 = 1 Compute mass percents using the mass fractions: Answer: | | | number of atoms | atom percent | mass percent Nb (niobium) | 1 | 33.3% | 92.90637/348.10637 × 100% = 26.69% Te (tellurium) | 2 | 66.7% | 255.20/348.10637 × 100% = 73.31%
Mass fraction pie chart
Mass fraction pie chart