Question

An Unidentified element has many of the same physical and chemical properties as magnesium and strontium but has a lower atomic mass than either of these elements. What is the most likely identity of this element?

Answer 1

The unidentified element is most likely beryllium (Be) as it belongs to the alkaline earth metal group, has similar properties to magnesium and strontium, and has a lower atomic mass than both.

Step-by-step explanation:

The most likely identity of the unidentified element with similar properties to magnesium and strontium but with a lower atomic mass is beryllium (Be). Beryllium belongs to the alkaline earth metal group, just like magnesium and strontium, and has a lower atomic mass than both of them.

Beryllium (atomic number 4) has 4 electrons in its outermost energy level, with the electron configuration [He]2s². Similarly, magnesium (atomic number 12) has 2 more electrons in its outermost energy level, and its electron configuration is [Ne]3s². Strontium (atomic number 38), on the other hand, has 6 more electrons in its outermost energy level, with the electron configuration [Kr]5s².

Therefore, based on the given information, the unidentified element with similar properties to magnesium and strontium but with a lower atomic mass is most likely beryllium (Be).