Question

analyzing data
patterns in electron configurations
as described by the quantum mechanical model of the atom, every electron has a precise amount of energy and occupies a specific atomic orbital. an electron configuration is the way that the electrons of an atom are arranged in the atomic orbitals. scientists have identified three rules that explain the most stable electron configuration for atoms. in this activity, you will use observed patterns to infer these three rules.
the table shows the patterns in electron configurations, but the table is incomplete. when complete, the table will show the ground state electron configurations for the first 12 elements. the middle section of the table uses boxes to represent atomic orbitals. each arrow (pointing up or down) represents an electron that occupies the orbital. the column at the far right represents electron configurations using numbers, letters, and superscripts.
electron configurations of the first 12 elements
atomic number element 1s 2s 2p_x 2p_y 2p_z 3s electron configuration
1 h ↑ 1s^1
2 he
3 li ↑↓ ↑ 1s^22s^1
4 be
5 b
6 c ↑↓ ↑↓ ↑ ↑ 1s^22s^22p^2
7 n ↑↓ ↑↓ ↑ ↑ ↑ 1s^22s^22p^3
8 o ↑↓ ↑↓ ↑↓ ↑ ↑ 1s^22s^22p^4
9 f
10 ne ↑↓ ↑↓ ↑↓ ↑↓ ↑↓ 1s^22s^22p^6
11 na ↑↓ ↑↓ ↑↓ ↑↓ ↑↓ ↑ 1s^22s^22p^63s^1
12 mg

Explanation:

Step1: Recall electron - filling rules

Use the Aufbau principle (fill orbitals from lowest to highest energy), Pauli - exclusion principle (each orbital can hold at most 2 electrons with opposite spins), and Hund's rule (put electrons in degenerate orbitals singly before pairing).

Step2: Fill orbitals for He

Helium has 2 electrons. The 1s orbital can hold 2 electrons. So, the electron - configuration is $1s^{2}$ and the orbital diagram has two electrons with opposite spins in the 1s box ($\uparrow\downarrow$).

Step3: Fill orbitals for Be

Beryllium has 4 electrons. First, fill the 1s orbital with 2 electrons ($\uparrow\downarrow$), then fill the 2s orbital with 2 electrons ($\uparrow\downarrow$). The electron - configuration is $1s^{2}2s^{2}$.

Step4: Fill orbitals for B

Boron has 5 electrons. Fill 1s with 2 electrons ($\uparrow\downarrow$), 2s with 2 electrons ($\uparrow\downarrow$), and then put 1 electron in the $2p_{x}$ orbital ($\uparrow$). The electron - configuration is $1s^{2}2s^{2}2p^{1}$.

Step5: Fill orbitals for F

Fluorine has 9 electrons. Fill 1s with 2 electrons ($\uparrow\downarrow$), 2s with 2 electrons ($\uparrow\downarrow$), fill $2p_{x}$ with 2 electrons ($\uparrow\downarrow$), $2p_{y}$ with 2 electrons ($\uparrow\downarrow$), and $2p_{z}$ with 1 electron ($\uparrow$). The electron - configuration is $1s^{2}2s^{2}2p^{5}$.

Step6: Fill orbitals for Mg

Magnesium has 12 electrons. Fill 1s with 2 electrons ($\uparrow\downarrow$), 2s with 2 electrons ($\uparrow\downarrow$), 2p with 6 electrons ($\uparrow\downarrow$ in each of $2p_{x}$, $2p_{y}$, $2p_{z}$), and 3s with 2 electrons ($\uparrow\downarrow$). The electron - configuration is $1s^{2}2s^{2}2p^{6}3s^{2}$.

Answer:

Atomic number	Element	1s	2s	$2p_{x}$	$2p_{y}$	$2p_{z}$	3s	Electron configuration
2	He	$\uparrow\downarrow$						$1s^{2}$
3	Li	$\uparrow\downarrow$	$\uparrow$					$1s^{2}2s^{1}$
4	Be	$\uparrow\downarrow$	$\uparrow\downarrow$					$1s^{2}2s^{2}$
5	B	$\uparrow\downarrow$	$\uparrow\downarrow$	$\uparrow$				$1s^{2}2s^{2}2p^{1}$
6	C	$\uparrow\downarrow$	$\uparrow\downarrow$	$\uparrow$	$\uparrow$			$1s^{2}2s^{2}2p^{2}$
7	N	$\uparrow\downarrow$	$\uparrow\downarrow$	$\uparrow$	$\uparrow$	$\uparrow$		$1s^{2}2s^{2}2p^{3}$
8	O	$\uparrow\downarrow$	$\uparrow\downarrow$	$\uparrow\downarrow$	$\uparrow$	$\uparrow$		$1s^{2}2s^{2}2p^{4}$
9	F	$\uparrow\downarrow$	$\uparrow\downarrow$	$\uparrow\downarrow$	$\uparrow\downarrow$	$\uparrow$		$1s^{2}2s^{2}2p^{5}$
10	Ne	$\uparrow\downarrow$	$\uparrow\downarrow$	$\uparrow\downarrow$	$\uparrow\downarrow$	$\uparrow\downarrow$		$1s^{2}2s^{2}2p^{6}$
11	Na	$\uparrow\downarrow$	$\uparrow\downarrow$	$\uparrow\downarrow$	$\uparrow\downarrow$	$\uparrow\downarrow$	$\uparrow$	$1s^{2}2s^{2}2p^{6}3s^{1}$
12	Mg	$\uparrow\downarrow$	$\uparrow\downarrow$	$\uparrow\downarrow$	$\uparrow\downarrow$	$\uparrow\downarrow$	$\uparrow\downarrow$	$1s^{2}2s^{2}2p^{6}3s^{2}$