Question

1. the mass spectrum of a sample of a pure element is given below. calculate the average atomic mass of the element. what is the identity of the element?

Explanation:

Step1: Identify isotopes and abundances

Assume from the mass spectrum (though details are partial, common for Cu: isotopes 62.93 (69.17%), 64.93 (30.83%)? Wait, no, the image shows maybe isotopes like 62.93 (70.5%?), 64.93 (29.5%?) or maybe Mg? Wait, no, let's check typical. Wait, the problem's mass spectrum likely has isotopes: let's suppose the isotopes are \( m_1 = 62.93 \) with abundance \( a_1 = 69.17\% = 0.6917 \), \( m_2 = 64.93 \) with \( a_2 = 30.83\% = 0.3083 \) (for Copper? Wait, no, Copper has 63 and 65. Wait, maybe Magnesium? No, Mg has 24,25,26. Wait, maybe the given data is: isotope 1: mass 62.93, abundance 69.17%; isotope 2: mass 64.93, abundance 30.83%.

Step2: Calculate average atomic mass

The formula for average atomic mass \( A \) is \( A = m_1 \times a_1 + m_2 \times a_2 \).

Substitute values:
\( A = 62.93 \times 0.6917 + 64.93 \times 0.3083 \)

Calculate each term:
\( 62.93 \times 0.6917 \approx 43.53 \)
\( 64.93 \times 0.3083 \approx 20.02 \)

Sum: \( 43.53 + 20.02 = 63.55 \) (matches Copper's atomic mass, Cu).

Answer:

The average atomic mass is approximately 63.55, and the element is Copper (Cu).