Question

electron configuration practice chemistry
in the space below, write the full ( unabbreviated) electron configurations of the following elements:

1. sodium
2. iron
3. bromine
4. barium
5. neptunium

f. in the space below, write the noble gas (abbreviated) electron configurations of the following elements:

1. cobalt
2. silver
3. tellurium
4. radium
5. lawrencium

g. determine what elements are denoted by the following electron configurations:

1. 1s²2s²2p⁶3s²3p⁴
2. 1s²2s²2p⁶3s²3p⁶4s²3d¹⁰4p⁶5s¹
3. kr 5s²4d¹⁰5p³
4. xe 6s²4f¹⁴5d⁶
5. rn 7s²5f¹¹

Explanation:

Step1: Recall electron - filling rules

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

Step2: Determine atomic numbers

Find the atomic number of each element, which is equal to the number of electrons in a neutral atom.

Step3: Write full electron configurations

Sodium (Na), atomic number = 11

$1s^{2}2s^{2}2p^{6}3s^{1}$

Iron (Fe), atomic number = 26

$1s^{2}2s^{2}2p^{6}3s^{2}3p^{6}4s^{2}3d^{6}$

Bromine (Br), atomic number = 35

$1s^{2}2s^{2}2p^{6}3s^{2}3p^{6}4s^{2}3d^{10}4p^{5}$

Barium (Ba), atomic number = 56

$1s^{2}2s^{2}2p^{6}3s^{2}3p^{6}4s^{2}3d^{10}4p^{6}5s^{2}4d^{10}5p^{6}6s^{2}$

Neptunium (Np), atomic number = 93

$1s^{2}2s^{2}2p^{6}3s^{2}3p^{6}4s^{2}3d^{10}4p^{6}5s^{2}4d^{10}5p^{6}6s^{2}4f^{14}5d^{10}6p^{6}7s^{2}5f^{4}6d^{1}$

Step4: Write noble - gas abbreviated electron configurations

Cobalt (Co), atomic number = 27

$[Ar]4s^{2}3d^{7}$

Silver (Ag), atomic number = 47

$[Kr]5s^{1}4d^{10}$

Tellurium (Te), atomic number = 52

$[Kr]5s^{2}4d^{10}5p^{4}$

Radium (Ra), atomic number = 88

$[Rn]7s^{2}$

Lawrencium (Lr), atomic number = 103

$[Rn]7s^{2}5f^{14}6d^{1}$

Step5: Identify elements from electron configurations

$1s^{2}2s^{2}2p^{6}3s^{2}3p^{4}$

Sulfur (S), since the total number of electrons is 16.

$1s^{2}2s^{2}2p^{6}3s^{2}3p^{6}4s^{2}3d^{10}4p^{6}5s^{1}$

Rubidium (Rb), as the total number of electrons is 37.

$[Kr]5s^{2}4d^{10}5p^{3}$

Antimony (Sb), adding the electrons from krypton (36) and the additional 15 electrons gives 51.

$[Xe]6s^{2}4f^{14}5d^{6}$

Osmium (Os), with xenon (54) plus 22 more electrons totaling 76.

$[Rn]7s^{2}5f^{11}$

Einsteinium (Es), with radon (86) plus 13 more electrons totaling 99.

Answer:

1. $1s^{2}2s^{2}2p^{6}3s^{1}$
2. $1s^{2}2s^{2}2p^{6}3s^{2}3p^{6}4s^{2}3d^{6}$
3. $1s^{2}2s^{2}2p^{6}3s^{2}3p^{6}4s^{2}3d^{10}4p^{5}$
4. $1s^{2}2s^{2}2p^{6}3s^{2}3p^{6}4s^{2}3d^{10}4p^{6}5s^{2}4d^{10}5p^{6}6s^{2}$
5. $1s^{2}2s^{2}2p^{6}3s^{2}3p^{6}4s^{2}3d^{10}4p^{6}5s^{2}4d^{10}5p^{6}6s^{2}4f^{14}5d^{10}6p^{6}7s^{2}5f^{4}6d^{1}$
6. $[Ar]4s^{2}3d^{7}$
7. $[Kr]5s^{1}4d^{10}$
8. $[Kr]5s^{2}4d^{10}5p^{4}$
9. $[Rn]7s^{2}$
10. $[Rn]7s^{2}5f^{14}6d^{1}$
11. Sulfur (S)
12. Rubidium (Rb)
13. Antimony (Sb)
14. Osmium (Os)
15. Einsteinium (Es)