Question

how many electrons does copper have if it has the following charge: cu²+?

Explanation:

Step1: Determine the number of protons

The atomic number of copper ($Cu$) is $29$. The atomic number is equal to the number of protons. So, the number of protons ($p$) is $29$.

Step2: Use the charge formula

For a neutral atom, the number of electrons ($e$) is equal to the number of protons. But for an ion with charge $Cu^{2 + }$, the formula for the charge ($q$) is $q=p - e$. Given $q = 2+$ (or $q=+ 2$), and $p = 29$.
Substitute into the formula: $2=29 - e$.

Step3: Solve for the number of electrons

Rearrange the equation $2=29 - e$ to solve for $e$.
Add $e$ to both sides: $2 + e=29$.
Subtract $2$ from both sides: $e=29 - 2$.

Answer:

$27$