Question

What PEL are the electrons in the 1st period elements

Answer 1

The electrons in the 1st period elements have their outermost electrons in the 1s orbital.

Explanation

In the first period of the periodic table, elements like hydrogen and helium occupy the orbital closest to the nucleus: the 1s orbital. Electrons within an atom are organized into different energy levels, and the period number indicates the highest energy level occupied in that period's elements. For the 1st period, that highest energy level is the first, so electrons reside in the 1s orbital.

This orbital can hold a maximum of two electrons, which is why the first period contains only two elements: hydrogen and helium. Hydrogen, with a single electron, occupies the 1s1 configuration, while helium, with two electrons, occupies the 1s2 configuration. These electrons are situated closer to the nucleus compared to electrons in higher energy levels, leading to their distinct properties.

The 1s orbital is spherical and closest to the nucleus, with the lowest energy within that period. As you move across periods in the periodic table, electrons progressively fill higher energy orbitals, but in the 1st period, the electrons specifically reside in the 1s orbital due to the low energy level of this period's elements. Understanding the arrangement of electrons in these orbitals helps in comprehending the reactivity and chemical behavior of these foundational elements.

Answer 2

The electrons in the 1st-period elements have a Principal Energy Level (PEL) of ( n = 1 ).

Step-by-step explanation:

The Principal Quantum Number (( n )) represents the main energy level of an electron in an atom. For the 1st period elements, such as hydrogen and helium, ( n = 1 ) is the principal energy level of their electrons. This implies that the electrons in these elements occupy the first energy shell around the nucleus. The principal quantum number is determined by the period number of the element. In this case, since we are considering the 1st period, ( n = 1 ).

The principal energy level (( n )) also indicates the distance of an electron from the nucleus. As ( n ) increases, the distance from the nucleus increases, and the energy level of the electron shell also increases. For 1st period elements, the electrons are in the innermost energy level, closest to the nucleus. This is consistent with the general trend across periods in the periodic table. Understanding the principal quantum number is crucial for predicting the electronic configuration and the behavior of electrons in different elements.

In summary, the Principal Energy Level (PEL) of electrons in the 1st-period elements is ( n = 1 ), denoting the first energy level or shell around the nucleus. This is a fundamental concept in quantum mechanics that helps explain the arrangement of electrons in atoms and their relationship to the periodic table.