Two of most unique elements on the periodic table are hydrogen and helium. What makes them so unique and removed from the other groups on the periodic table?
a
Unlike all other elements, hydrogen and helium are gases
b
Unlike all other elements, hydrogen and helium are not considered metals
c
Unlike all other elements, hydrogen and helium only have a maximum of 2 valence electrons
d
Unlike all other elements, hydrogen and helium have very limited properties
A. Unlike all other elements, hydrogen and helium are gases
What is special about hydrogen and helium?
Hydrogen and helium are the lightest elements in the periodic table having mass number 1 and 2 respectively. They both exist in the form of gases at room temperature. Both Hydrogen and helium are the two most common elements in the universe. Hydrogen make up about 75% of all matter present in the universe. Hydrogen belongs to the metal group but it is not metal but a gas.
So we can conclude that option A is the right answer for the given question.
and reactivity
Correct answer is actually A.
The correct answer is c: Unlike all other elements, hydrogen and helium only have a maximum of 2 valence electrons.
Hydrogen and helium are unique because they have very low atomic numbers, meaning they have the smallest number of electrons in their respective periods.
Hydrogen is categorized as a nonmetal and is the only element on the periodic table that does not belong to any specific group. It is a gas at room temperature and has only one electron, which means it can only form one covalent bond.
Helium, on the other hand, is categorized as a noble gas and belongs to Group 18. It is also a gas at room temperature and has two electrons. Noble gases are known for their stable electronic configurations, and helium has a full valence shell with only two electrons.
Therefore, both hydrogen and helium stand out from other elements because they have a maximum of two valence electrons, which gives them unique chemical properties compared to other elements on the periodic table.