Em tham khảo nha :
\(\begin{array}{l}
1.\\
1{s^2}2{s^2}2{p^6}3{s^2}3{p^3}\\
Z = 15\\
2.\\
1{s^2}2{s^2}2{p^6}3{s^2}3{p^6}4{s^1}\\
Z = 19\\
3.\\
Z = \dfrac{{3,2 \times {{10}^{ - 18}}}}{{6,02 \times {{10}^{ - 19}}}} = 5\\
1{s^2}2{s^2}2{p^1}\\
4.\\
1{s^2}2{s^2}2{p^6}3{s^2}3{p^2}\\
Z = 14\\
5.\\
1{s^2}2{s^2}2{p^6}3{s^2}3{p^5}\\
Z = 17\\
6.\\
1{s^2}2{s^2}2{p^6}3{s^2}3{p^6}4{s^1}\\
Z = 19\\
1{s^2}2{s^2}2{p^6}3{s^2}3{p^6}4{s^2}\\
Z = 20\\
7.\\
1{s^2}2{s^2}2{p^6}3{s^2}3{p^6}3{d^{10}}4{s^2}4{p^5}\\
Z = 35\\
8.\\
1{s^2}2{s^2}2{p^6}3{s^2}3{p^6}4{s^1}\\
Z = 19\\
9.\\
1{s^2}2{s^2}2{p^5}\\
Z = 9\\
10.\\
2p + n = 21 \Rightarrow n = 21 - 2p\\
1 \le \dfrac{n}{p} \le 1,5 \Rightarrow 1 \le \dfrac{{21 - 2p}}{p} \le 1,5\\
6 \le p \le 7\\
TH1:p = 6\\
n = 21 - 6 \times 2 = 9\text{(Loại)}\\
TH2:p = 7\\
n = 21 - 7 \times 2 = 7\text{(Nhận)}\\
Z = 7\\
1{s^2}2{s^2}2{p^3}\\
11.\\
2p + n = 33 + 1 \Rightarrow n = 34 - 2p\\
1 \le \dfrac{n}{p} \le 1,5 \Rightarrow 1 \le \dfrac{{34 - 2p}}{p} \le 1,5\\
9,7 \le p \le 11,3\\
TH1:p = 10\\
n = 34 - 10 \times 2 = 24\text{(Loại)}\\
TH2:p = 11\\
n = 34 - 11 \times 2 = 12\text{(Nhận)}\\
Z = 11\\
1{s^2}2{s^2}2{p^6}3{s^1}\\
12.\\
1{s^2}2{s^2}2{p^6}3{s^2}3{p^6}4{s^1}\\
Z = 19\\
13.\\
1{s^2}2{s^2}2{p^6}3{s^2}\\
Z = 12\\
1{s^2}2{s^2}2{p^6}3{s^2}3{p^1}\\
Z = 13\\
1{s^2}2{s^2}2{p^6}3{s^2}3{p^2}\\
Z = 14\\
1{s^2}2{s^2}2{p^6}3{s^2}3{p^3}\\
Z = 15\\
1{s^2}2{s^2}2{p^6}3{s^2}3{p^4}\\
Z = 16\\
1{s^2}2{s^2}2{p^6}3{s^2}3{p^5}\\
Z = 17\\
1{s^2}2{s^2}2{p^6}3{s^2}3{p^6}\\
Z = 18
\end{array}\)
