Question

question 19 (1 point)
which element has the electron configuration 1s²2s²2p⁶3s²3p⁵?
chlorine
phosphorus
sulphur
iron

Explanation:

To find the element with the electron configuration \(1s^{2}2s^{2}2p^{6}3s^{2}3p^{5}\), we first calculate the total number of electrons.

• Step 1: Calculate the number of electrons in each sub - shell
• For \(1s^{2}\), the number of electrons is \(2\).
• For \(2s^{2}\), the number of electrons is \(2\).
• For \(2p^{6}\), the number of electrons is \(6\).
• For \(3s^{2}\), the number of electrons is \(2\).
• For \(3p^{5}\), the number of electrons is \(5\).
• Step 2: Sum up the number of electrons

$$2 + 2+6 + 2+5=17$$

The atomic number of an element is equal to the number of electrons in a neutral atom. Chlorine (\(Cl\)) has an atomic number of \(17\). Phosphorus (\(P\)) has an atomic number of \(15\) (\(1s^{2}2s^{2}2p^{6}3s^{2}3p^{3}\)), sulphur (\(S\)) has an atomic number of \(16\) (\(1s^{2}2s^{2}2p^{6}3s^{2}3p^{4}\)) and iron (\(Fe\)) has an atomic number of \(26\) (\(1s^{2}2s^{2}2p^{6}3s^{2}3p^{6}4s^{2}3d^{6}\)).

Answer:

chlorine