Is this statement true "all elements are most stable with 8 valence electrons
No, this statement is not true. While the octet rule suggests that most elements are stable when they have 8 valence electrons, there are exceptions. For example, hydrogen and helium only require 2 valence electrons to reach stability, while elements in the third period and beyond can have expanded octets and exceed the 8 valence electron rule.
No, this statement is not entirely true. While the octet rule suggests that many elements tend to be more stable when they have a full outermost electron shell with 8 valence electrons, there are exceptions to this rule. For example, hydrogen (H) only requires 2 valence electrons to achieve stability, while elements in period 3 and beyond in the periodic table can accommodate more than 8 valence electrons due to the presence of d-orbitals. Additionally, some elements can have stable configurations with less than 8 valence electrons. Examples include helium (He) with 2 valence electrons and beryllium (Be) with 4 valence electrons.
The statement that all elements are most stable with 8 valence electrons is a generalization known as the octet rule. It suggests that atoms tend to gain, lose, or share electrons in order to achieve a stable electron configuration similar to the noble gases, which have 8 valence electrons.
If you're wondering how to verify this statement for individual elements, you can look at the periodic table to determine the number of valence electrons for each element. The number of valence electrons corresponds to the group number for elements in Groups 1, 2, and 13 to 18.
For example, elements in Group 1 (such as hydrogen and lithium) have 1 valence electron, elements in Group 2 (such as beryllium and magnesium) have 2 valence electrons, and so on.
Most elements, particularly nonmetals, tend to form chemical bonds in order to achieve a stable electron configuration with 8 valence electrons, either by gaining or losing electrons, or by sharing electrons with other atoms. However, there are exceptions to the octet rule, especially for elements in the first two periods of the periodic table, which can have fewer than 8 valence electrons due to their smaller valence shell.