Question
An element X belongs to the third period of p-block. It has 4 electrons in the outermost shell. Name the element.
✓
Answer
The outer configuration of the element is $3 \mathrm{s}^2 ~3 \mathrm{p}^2$ (as it has 4 elements in outermost shell). Thus, the complete configuration is $1 s^2, 2 s^2 2 p^6, 3 s^2, 3 p^2$. So the atomic number is $2+8+4=14$. Hence, the element is silicon.
Need a full question paper?
Generate a complete, print-ready paper with questions like this in minutes — across 16+ boards, with answer keys.
Explore more
Similar questions
What type of bonds are broken when water evaporates.
Is pyrolle
aromatic compound or not? Give reason.- What do you mean by sink? Give one example.
- What is the sink for hydrocarbons and why?
$\text{SO}_3^{2-}$ is Bronsted base or acid and why?
→Arrange the following in decreasing order of -I effect:
$-\text{Br},-\text{Cl},-\text{F}$
→$-\text{Br},-\text{Cl},-\text{F}$
Write the formula of calculate molarity?
Which two discoveries put strong challenge to the Bohr model?
Name some impurities found in brine solution.
Can we apply Heisenberg's uncertainty principle to a stationary electron? Why or why not?
The first $(\Delta_{1}\text{H}_{1})$ and the second $(\Delta_{1}\text{H}_{1})$ ionization enthalpies (in $\mathrm{kJ} \mathrm{~mol}^{-1}$ ) and the $(\Delta_{1}\text{H}_{1})$ electron gain enthalpy (in $\mathrm{kJ} \mathrm{~mol}^{-1}$ ) of a few elements are given below:
Which of the above elements is likely to be:
The least reactive element.
→| Elements | $\Delta\text{H}_{1}$ | $\Delta{\text{H}}_{2}$ | $\Delta_{\text{eg}}\text{H}$ |
| I | 520 | 7300 | -60 |
| II | 419 | 3051 | -48 |
| III | 1681 | 3374 | -328 |
| IV | 1008 | 1846 | -295 |
| V | 2372 | 5251 | +48 |
| VI | 738 | 1451 | -40 |
The least reactive element.