Answer:
[Ne] 3s2 3p2
Explanation:
Neon (Ne) is the noble gas right before silicon (Si).
Then right after neon is the 3s subshell. It has two electrons and is full.
After 3s comes the 3p subshell, and silicon only has two electrons in the 3p subshell (you can just count the electrons in each subshell on your periodic table).
Answer:
It represents the <em>number of atoms</em> of that particular element present in the compound. In C₂H₄O₂ there are 2 Carbon atoms, 4 Hydrogen atoms and 2 Oxygen atoms.
The reactivity of a metal is determined by these things.
Firstly, the number of electrons in the outer shell; the fewer the number of electrons in the outer shell, the more reactive the metal.
The number of electron shells also affects reactivity, the more electron shells there are, the more reactive the metal.
