If the symbol X represents a central atom, Y represents outer atoms, and Z represents lone pairs on the central atom, the structure Y---X---Y (2 lone pairs around X) could be abbreviated as XY2Z2. Classify these structures according to their shape.

Molecular Geometries:

linear
bent 120
bent 109
trigonal pyramidal
T-shaped
see saw
square planar
square pyramidal

Possiblities:

XY4Z2
XY5Z
XY2Z
XY2Z3
XY4Z
XY2Z2
XY3Z2
XY3Z

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.  

the seeing the electronic configuration we can say that the element is fluorine.

fluorine is the most electronegative element in the periodic table.

but by only seeing the configuration we cannot say about its reactivity because we don't know if its configuration after excitation or by addition of electrons.

but if not then, it is the lightest halogen and exists as a highly toxic pale yellow diatomic gas at standard conditions. as the most electronegative element, it is extremely reactive: almost all other elements, including some noble gases, form compounds with fluorine.