Question

using patterns on the periodic table, write out the standard long - form electron configuration for each of the following elements.

1. na
2. s
3. v
4. fe
5. i

using patterns on the periodic table, write out the noble gas electron configuration for each of the following elements.

1. cr
2. rb
3. ar
4. sn
5. al

answer the questions below.

1. how many electrons are in the outermost energy level of sodium?

a) 1 b) 2 c) 8 d) 11 e) 4

1. the number of unpaired electrons in a nitrogen atom is

a) 1 b) 3 c) 5 d) 7 e) nitrogen has no unpaired electrons

1. the following is the correct noble gas configuration for potassium

a) kr4s1 b) ar4s1 c) ar3d104s1 d) ar4s24p6

1. the electron configuration for calcium is

a) 1s22s22p63s23p64s2 b) 1s22s22p63s23p64s1
c) 1s22s22p63s23p63d104s2 d) 1s22s22p63s23p64s24p6

1. the noble gas configuration for br is

a) kr4s24p5 b) kr5s1 c) ar3d104s2 d) ar3d104s24p5

Explanation:

Step1: Recall electron - configuration rules

Use the Aufbau principle, Pauli - exclusion principle, and Hund's rule to write electron configurations.

Step2: Write standard long - form electron configurations

• Na (Sodium, atomic number = 11): $1s^{2}2s^{2}2p^{6}3s^{1}$
• S (Sulfur, atomic number = 16): $1s^{2}2s^{2}2p^{6}3s^{2}3p^{4}$
• N (Nitrogen, atomic number = 7): $1s^{2}2s^{2}2p^{3}$
• Fe (Iron, atomic number = 26): $1s^{2}2s^{2}2p^{6}3s^{2}3p^{6}4s^{2}3d^{6}$
• I (Iodine, atomic number = 53): $1s^{2}2s^{2}2p^{6}3s^{2}3p^{6}4s^{2}3d^{10}4p^{6}5s^{2}4d^{10}5p^{5}$

Step3: Write noble - gas electron configurations

• Cr (Chromium, atomic number = 24): $[Ar]4s^{1}3d^{5}$
• Rb (Rubidium, atomic number = 37): $[Kr]5s^{1}$
• Ar (Argon, atomic number = 18): $[Ne]3s^{2}3p^{6}$
• Sn (Tin, atomic number = 50): $[Kr]5s^{2}4d^{10}5p^{2}$
• Al (Aluminum, atomic number = 13): $[Ne]3s^{2}3p^{1}$

Step4: Answer multiple - choice questions

Question 11

Sodium (Na) has an electron configuration of $1s^{2}2s^{2}2p^{6}3s^{1}$. The outermost energy level is the 3rd level, and it has 1 electron. So the answer is a) 1.

Question 12

Nitrogen (N) has an electron configuration of $1s^{2}2s^{2}2p^{3}$. In the 2p sub - shell, according to Hund's rule, the 3 electrons are unpaired. So the number of unpaired electrons is 3, and the answer is b) 3.

Question 13

(No element specified for the noble - gas configuration question. Assuming it's a general knowledge check, noble - gas configurations follow the pattern of filling orbitals).

Question 14

Calcium (Ca, atomic number = 20) has an electron configuration of $1s^{2}2s^{2}2p^{6}3s^{2}3p^{6}4s^{2}$.

Question 15

(No element specified clearly for the noble - gas configuration question).

Answer:

1. Na: $1s^{2}2s^{2}2p^{6}3s^{1}$
2. S: $1s^{2}2s^{2}2p^{6}3s^{2}3p^{4}$
3. N: $1s^{2}2s^{2}2p^{3}$
4. Fe: $1s^{2}2s^{2}2p^{6}3s^{2}3p^{6}4s^{2}3d^{6}$
5. I: $1s^{2}2s^{2}2p^{6}3s^{2}3p^{6}4s^{2}3d^{10}4p^{6}5s^{2}4d^{10}5p^{5}$
6. Cr: $[Ar]4s^{1}3d^{5}$
7. Rb: $[Kr]5s^{1}$
8. Ar: $[Ne]3s^{2}3p^{6}$
9. Sn: $[Kr]5s^{2}4d^{10}5p^{2}$
10. Al: $[Ne]3s^{2}3p^{1}$
11. a) 1
12. b) 3
13. (No clear element for answer)
14. $1s^{2}2s^{2}2p^{6}3s^{2}3p^{6}4s^{2}$
15. (No clear element for answer)