A student is studying lithium, a highly reactive element that is used in the medical field. Which characteristic is the student studying to determine the reactivity of lithium? Refer to the Periodic Table A.
The 3 protons in each atom of lithium.

B.
The 4 neutrons in each atom of lithium.

C.
The 3 total electrons in each atom of lithium.

D.
The 1 valence electron in each atom of lithium.

D

Explanation:

it has a single valence electron which is very easily given up in order to create bonds and form compounds.

answer is: nuclear fusion produces elements that are heavier than helium.

nuclei combine to form a heavier nucleus, releasing energy.  

for example, fusion of hydrogen atoms at the sun.  

this fusion nuclear reaction is in the inner core of the sun and hydrogen (atomic number 1) is conveted into helium (atomic number 2).  

the inner core is the central region of the sun and all solar energy is produced in the core by nuclear fusion.