First Period Elements Identification
The periods in the periodic table represent the principal energy levels (or electron shells) of atoms.
The first period corresponds to the first principal energy level (n=1). This energy level can only accommodate a maximum of two electrons, specifically in the 1s subshell.
- Number of Elements: The first period contains only two elements.
- Elements Present:
- Hydrogen (H): Atomic number 1. Its electron configuration is $1s^1$.
- Helium (He): Atomic number 2. Its electron configuration is $1s^2$.
Therefore, the first period is the shortest period in the periodic table, containing just these two elements.
Important Questions from Periodic Classification
Element X forms a chloride with the formula XCl2, which is a solid with high melting point. X would most likely be in the same group of periodic table as
Element X forms a chloride with the formula XCl2, which is a solid with high melting point. X would most likely be in the same group of periodic table as
- Which of the following statements is NOT correct with reference to the p-block elements?
- Where did Mendeleev arrange the elements in the periodic table with similar properties?
- What was the unknown element under aluminium called?
