Question

Calculate the average atomic mass of the mystery element given the isotopic data below.

Sample size: Isotope #1 85 - particles, Isotope #2 - 90 particles, Isotope #3 - 45 particles
Masses: Isotope #1 total mass = 1630 amu, Isotope 2 total mass = 1950 amu, Isotope #3 total mass = 1030 amu

Answer 1

The average atomic mass of the mystery element : 1637.88 amu

Further explanation

The elements in nature have several types of isotopes

Isotopes are elements that have the same Atomic Number (Proton)

Atomic mass is the average atomic mass of all its isotopes

In determining the mass of an atom, as a standard is the mass of 1 carbon-12 atom whose mass is 12 amu

An atomic mass unit = amu is a relative atomic mass of 1/12 the mass of an atom of carbon-12.

The 'amu' unit has now been replaced with a unit of 'u' only

Mass atom X = mass isotope 1 . % + mass isotope 2.% ..

Isotope #1 - 85 particles, Isotope #2 - 90 particles, Isotope #3 - 45 particles, so total particles :

`\tt 85+90+45=220~particles`

% particles :

• Isotope #1

`\tt (85)/(220)=0.386`

• Isotope #2

`\tt (90)/(220)=0.409`

• Isotope #3

`\tt (45)/(220)=0.205`

The average atomic mass of the mystery element

`\tt =0.386* 1630+0.409* 1950+0.205* 1030\\\\=\boxed{\bold{1637.88}}`