What symbol would represent a chlorine ion with a stable arrangement of eight valence electrons?

Cl⁻

Explanation:

Elements in the periodic table (with the exception of group 0 elements) want to achieve there octet configuration and as such gain or lose electron(s) in order to achieve that. When an atom loses electron(s), it becomes positively charged and when it gains, it becomes negatively charged.

Chlorine (Cl) has 17 electrons.

₁₇Cl  →  1S² 2S² 2P⁶ 3S² 3P⁵

From the above, it can be deduced that chlorine has 7 (5+2) electrons in its outermost shell and hence needs just one electron to achieve it's octet configuration. When chlorine gains this one electron it requires to achieve it's octet configuration, it becomes negatively charged (as explained earlier). Thus, it is represented as Cl⁻.

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.  

answermeridional ;