An element have atomic number 15, its valence electrons group number and valency are respectively

Options

A. 5,15,3
B. 6,15,3
C. 15,6,3
D. 6,16,4

Answer

To solve the question regarding the element with atomic number 15, we will follow these steps:

### Step 1: Identify the Element
The atomic number 15 corresponds to the element phosphorus (P).

### Step 2: Determine the Electronic Configuration
The electronic configuration of phosphorus can be determined as follows:
- The first shell can hold 2 electrons (1s²).
- The second shell can hold 8 electrons (2s² 2p⁶).
- The third shell can hold up to 18 electrons, but for phosphorus, it has 5 electrons (3s² 3p³).

Thus, the complete electronic configuration for phosphorus is:
\[ \text{1s}^2 \, \text{2s}^2 \, \text{2p}^6 \, \text{3s}^2 \, \text{3p}^3 \]

### Step 3: Count the Valence Electrons
Valence electrons are the electrons present in the outermost shell. For phosphorus, the outermost shell is the third shell, which has:
- 2 electrons in the 3s subshell
- 3 electrons in the 3p subshell

Thus, the total number of valence electrons is:
\[ 2 + 3 = 5 \]

### Step 4: Determine the Group Number
For p-block elements, the group number can be calculated by adding 10 to the number of valence electrons. Since phosphorus has 5 valence electrons:
\[ \text{Group Number} = 10 + 5 = 15 \]

### Step 5: Calculate the Valency
Valency is defined as the number of electrons an atom needs to gain, lose, or share to achieve a full outer shell. For phosphorus, which has 5 valence electrons, it needs 3 more electrons to complete its octet (8 electrons in the outer shell). Therefore, the valency of phosphorus is:
\[ \text{Valency} = 3 \]

### Final Summary
- Valence Electrons: 5
- Group Number: 15
- Valency: 3