Question

29 ccc patterns what element has an electron configuration of 1s²2s²2p⁶3s²3p⁶4s² and which block is it in? use the periodic table.

Explanation:

Step1: Count the total number of electrons

The electron - configuration is $1s^{2}2s^{2}2p^{6}3s^{2}3p^{6}4s^{2}$. Calculate the sum of the exponents: $2 + 2+6 + 2+6 + 2=20$.

Step2: Identify the element based on the atomic number

The atomic number of an element is equal to the number of electrons in a neutral atom. An element with an atomic number of 20 is calcium (Ca).

Step3: Determine the block

The last - filled sub - shell is $4s$. Elements with the last - filled sub - shell as $s$ are in the s - block.

Answer:

The element is calcium (Ca) and it is in the s - block.