Question

question 17
1 pts
the periodic table can be used to give the electron configuration of an element according to the period (row), block (subshell), and number of electrons (steps taken) as one moves from hydrogen to the element to be specified.
using the period table, trace a stepwise path from hydrogen to the element below and give the electron configuration by specifying each of the periods (row), block (subshell), and the number of electrons (steps - superscripted)
what is the electron configuration for li?
1s²2s²
1s²2s¹
1s²2s²2p²
1s²2s²2p¹

Explanation:

Step1: Recall electron - filling rules

Electrons fill orbitals in the order of increasing energy: 1s before 2s, and 2s before 2p. The s - subshell can hold a maximum of 2 electrons and the p - subshell can hold a maximum of 6 electrons.

Step2: Determine number of electrons in Li

Lithium (Li) has an atomic number of 3, which means it has 3 electrons.

Step3: Fill the orbitals

The first 2 electrons fill the 1s orbital (1s²), and the remaining 1 electron fills the 2s orbital (2s¹). So the electron - configuration is 1s²2s¹.

Answer:

1s²2s¹