# Question b4ab9

Oct 23, 2017

Here's what I got.

#### Explanation:

For starters, calculate the charge of the ion by using the equation

color(blue)(ul(color(black)("net charge" = "no. of protons " - " no. of electrons"#

$\text{net charge} = 52 - 54 = - 2$

This tells you that the ion carries a $2 -$ charge, which implies that you are dealing with a negatively charged ion, or anion.

Now, the isotope notation of this ion requires

• the atomic number of the element, $Z$
• the mass number of the isotope, $A$

In your case, you know that the element has $52$ protons, which means that

$Z = 52$

In order to find the mass number of the isotope, simply add the number of protons and the number of neutrons present in the nucleus.

$A = \text{52 protons + 76 neutrons}$

$A = \text{128 nucleuons}$

This means that the symbol of the neutral isotope will look like this

$\text{_(color(white)(1)52)^128"X}$

A quick look in the Periodic Table will reveal that you're dealing with tellurium-128, an isotope of tellurium, $\text{Te}$.

$\text{_(color(white)(1)52)^128"Te}$

Finally, to show that this is an anion and not a neutral atom, add the net charge.

${\text{_(color(white)(1)52)^128"Te}}^{2 -}$