Question

use the data table below to answer the following questions:

isotope	atomic mass (amu)	natural abundance
2	10.04	4.55%
3	11.1	1.35%

1. what do these isotopes have in common?
2. what is different about these isotopes?
3. calculate the average atomic mass of this element and determine its identity.

(9.01×94.1)+(10.04×4.55)+(11.1×1.35)
= 906.508
÷ 100
= 9.06508 amu
be = beryllium

1. based on your answer above, complete the table below.

isotope	nuclear symbol	isotope name
2
3

Explanation:

Step1: Recall isotope definition

Isotopes are atoms of the same element. They have the same number of protons.

Step2: Identify difference in isotopes

Isotopes have different numbers of neutrons, resulting in different atomic masses.

Step3: Calculate average atomic mass

The formula for average atomic mass is $\sum_{i = 1}^{n}(m_i\times a_i)$, where $m_i$ is the atomic - mass of isotope $i$ and $a_i$ is the natural - abundance of isotope $i$ (expressed as a decimal).
$a_1=0.941$, $m_1 = 9.01$, $a_2 = 0.0455$, $m_2=10.04$, $a_3=0.0135$, $m_3 = 11.1$
Average atomic mass$=(9.01\times0.941)+(10.04\times0.0455)+(11.1\times0.0135)$
$=8.47841+0.45682 + 0.14985$
$=9.08508\approx9.09$ amu.
The element with an average atomic mass of approximately $9.09$ amu is Beryllium (Be).

Step4: Determine nuclear symbols and isotope names

For isotope 1:

• Nuclear symbol: $^{9}_{4}Be$ (since atomic number of Be is 4 and mass number is approximately 9)
• Isotope name: Beryllium - 9

For isotope 2:

• Nuclear symbol: $^{10}_{4}Be$
• Isotope name: Beryllium - 10

For isotope 3:

• Nuclear symbol: $^{11}_{4}Be$
• Isotope name: Beryllium - 11

Answer:

1. They have the same number of protons.
2. They have different numbers of neutrons and different atomic masses.
3. Average atomic mass is approximately $9.09$ amu, and the element is Beryllium (Be).

4.

Isotope	Nuclear Symbol	Isotope Name
2	$^{10}_{4}Be$	Beryllium - 10
3	$^{11}_{4}Be$	Beryllium - 11