Question

write the electron configuration for the following elements. (ex. na = 1s²2s²2p⁶3s¹) 4. si 5. cr 6. ba 7. br

Explanation:

Step1: Recall electron - filling rules

Use the Aufbau principle, Pauli - exclusion principle, and Hund's rule.

Step2: Determine atomic numbers

Si (Silicon) has atomic number 14, Cr (Chromium) has atomic number 24, Ba (Barium) has atomic number 56, Br (Bromine) has atomic number 35.

Step3: Write electron configurations

For Si: 1s²2s²2p⁶3s²3p².
For Cr: 1s²2s²2p⁶3s²3p⁶4s¹3d⁵ (due to half - filled d - subshell stability).
For Ba: 1s²2s²2p⁶3s²3p⁶4s²3d¹⁰4p⁶5s²4d¹⁰5p⁶6s².
For Br: 1s²2s²2p⁶3s²3p⁶4s²3d¹⁰4p⁵.

Answer:

Si: 1s²2s²2p⁶3s²3p²
Cr: 1s²2s²2p⁶3s²3p⁶4s¹3d⁵
Ba: 1s²2s²2p⁶3s²3p⁶4s²3d¹⁰4p⁶5s²4d¹⁰5p⁶6s²
Br: 1s²2s²2p⁶3s²3p⁶4s²3d¹⁰4p⁵