On considère un atome dont de noyau contient 14 dreutro son corteye electronique a une change tolare egle& +20,8X10-19C Trouver son numera atomique 2 et sa masse atomique A

The charge of a single electron is $e = 1.602 \times 10^{-19} \text{ C}$. The problem states that the total charge of the electron cloud is $+20.8 \times 10^{-19} \text{ C}$. Since electrons carry a negative charge, a positive charge for the electron cloud is physically impossible. We will assume that the given value represents the magnitude of the total charge of the electrons in a neutral atom, or the charge of the nucleus. In a neutral atom, the number of electrons is equal to the number of protons, which is the atomic number $Z$.

The number of protons $Z$ is calculated by dividing the total charge by the elementary charge:

$$Z = \frac{\text{Total charge}}{\text{Elementary charge}}$$ $$Z = \frac{20.8 \times 10^{-19} \text{ C}}{1.602 \times 10^{-19} \text{ C}}$$ $$Z \approx 12.9837$$

Since the atomic number must be an integer, we round it to the nearest whole number:

$$Z = 13$$

The mass number $A$ is the sum of the number of protons ($Z$) and the number of neutrons ($N$) in the nucleus.
We are given that the nucleus contains $N = 14$ neutrons.

$$A = Z + N$$ $$A = 13 + 14$$ $$A = 27$$

The atomic number is $Z=13$ and the mass number is $A=27$.

The atomic number $Z$ is $\boxed{13}$.
The mass number $A$ is $\boxed{27}$.