Question

show all work!! (unit 4l frq) (3 points per question)

1. which element has the electron configuration 1s² 2s¹?
2. which element has the orbital notation : ↑↓ 1s ↑↓ 2s ↑↓↑↓↑↓ 2p?
3. write the electron configuration for phosphorus.
4. how many valence electrons does phosphorus have?
5. draw the lewis dot diagram for phosphorus.

Explanation:

Step1: Recall electron - configuration rules

The atomic number is equal to the number of electrons in a neutral atom. For the electron configuration $1s^{2}2s^{1}$, the total number of electrons is $2 + 1=3$.

Step2: Identify the element

The element with atomic number 3 is Lithium (Li).

Step3: Analyze the orbital notation

The given orbital notation shows 2 electrons in 1s, 2 electrons in 2s and 6 electrons in 2p. The total number of electrons is $2+2 + 6=10$. The element with 10 electrons is Neon (Ne).

Step4: Write electron - configuration for Phosphorus

Phosphorus has an atomic number of 15. Using the Aufbau principle, the electron - configuration is $1s^{2}2s^{2}2p^{6}3s^{2}3p^{3}$.

Step5: Determine valence electrons

Valence electrons are the electrons in the outermost shell. For Phosphorus with electron - configuration $1s^{2}2s^{2}2p^{6}3s^{2}3p^{3}$, the outermost shell is the third shell ($n = 3$) and it has $2+3 = 5$ valence electrons.

Step6: Draw Lewis dot diagram

The Lewis dot diagram for Phosphorus shows 5 dots around the symbol 'P' representing its 5 valence electrons.

Answer:

1. Lithium (Li)
2. Neon (Ne)
3. $1s^{2}2s^{2}2p^{6}3s^{2}3p^{3}$
4. 5
5. Draw 5 dots around the symbol 'P'