a, $A=Z+N=e+N=13+14=27$
$⇒$$ X: ^{27}_{13}Al$
b, ta có $\left \{ {{p+N=26} \atop {N-p=2}} \right.$
$⇒$$\left \{ {{N=14} \atop {p=12}} \right.$
$^{26}_{12}X$
a) vì số p = e
nên P+e=2p
số hạt mang điện là 13 × 2 =26
kí hiệu của nguyên tử X là: 26/14 X
b) ta có: n-p=2 ⇔ n=14
n+p=26 p=12
mà p=e=12⇒số hạt mang điện là 12×2=24
kí hiệu của nguyên tử X là:
$\frac{24}{14}$X
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