Question

activity a (continued from previous page)

1. compare: how are the electrons in the 2p subshell similar to passengers getting on a bus?

1. practice: in the spaces below, write and illustrate electron configurations for the next four elements: nitrogen, oxygen, fluorine, and neon. when you are finished, use the gizmo to check your work. correct any improper configurations.

nitrogen configuration:
oxygen configuration:
fluorine configuration:
neon configuration:

1. apply: atoms are most stable when their outermost shell is full. if their outermost shell is not full, atoms tend to gain, lose, or share electrons until the shell fills up. while doing this, atoms react and form chemical bonds with other atoms.

based on this, what can you infer about the reactivity of helium and neon?

1. think and discuss: select the periodic table tab, and look at the second row, or period of the table. how does this row reflect the subshells of the second shell?

Explanation:

Step1: Answer question 7

Electrons fill orbitals in 2p sub - shell one at a time (like passengers getting on a bus one by one) following Hund's rule, which states that electrons will occupy empty orbitals of the same energy (degenerate orbitals) singly before pairing up.

Step2: Answer question 8

• Nitrogen (N, atomic number = 7): Electron configuration is $1s^{2}2s^{2}2p^{3}$. In orbital - box notation, 1s has 2 paired electrons (↑↓), 2s has 2 paired electrons (↑↓), and 2p has 3 unpaired electrons (↑ ↑ ↑).
• Oxygen (O, atomic number = 8): Electron configuration is $1s^{2}2s^{2}2p^{4}$. In orbital - box notation, 1s has 2 paired electrons (↑↓), 2s has 2 paired electrons (↑↓), and 2p has 4 electrons with 2 unpaired (↑↓ ↑ ↑).
• Fluorine (F, atomic number = 9): Electron configuration is $1s^{2}2s^{2}2p^{5}$. In orbital - box notation, 1s has 2 paired electrons (↑↓), 2s has 2 paired electrons (↑↓), and 2p has 5 electrons with 1 unpaired (↑↓ ↑↓ ↑).
• Neon (Ne, atomic number = 10): Electron configuration is $1s^{2}2s^{2}2p^{6}$. In orbital - box notation, 1s has 2 paired electrons (↑↓), 2s has 2 paired electrons (↑↓), and 2p has 6 paired electrons (↑↓ ↑↓ ↑↓).

Step3: Answer question 9

Helium and neon have full outermost shells. Helium has a full first shell (2 electrons) and neon has a full second shell (8 electrons). So, they are very stable and have low reactivity.

Step4: Answer question 10

The second row of the periodic table corresponds to the filling of the second shell. The first two elements (lithium and beryllium) fill the 2s sub - shell. The next six elements (boron to neon) fill the 2p sub - shell. This reflects the order of electron filling in the subshells of the second shell according to the Aufbau principle.

Answer:

1. Electrons fill 2p orbitals one - by - one like passengers boarding a bus following Hund's rule.
2. Nitrogen: $1s^{2}2s^{2}2p^{3}$, 1s(↑↓) 2s(↑↓) 2p(↑ ↑ ↑); Oxygen: $1s^{2}2s^{2}2p^{4}$, 1s(↑↓) 2s(↑↓) 2p(↑↓ ↑ ↑); Fluorine: $1s^{2}2s^{2}2p^{5}$, 1s(↑↓) 2s(↑↓) 2p(↑↓ ↑↓ ↑); Neon: $1s^{2}2s^{2}2p^{6}$, 1s(↑↓) 2s(↑↓) 2p(↑↓ ↑↓ ↑↓)
3. Helium and neon are unreactive as they have full outermost shells.
4. The first two elements fill 2s, and the next six fill 2p, reflecting electron - filling order in the second shell.