Answer:
In first shell 2 electrons are present and 7 electrons are present in last shell
Explanation:
Dots are used to represent electrons.
When fireworks go off, they produce smoke, which is evidence of a new substance being created.
2Na + Cl2 ------>2 Na⁺Cl⁻
Na⁺Cl⁻ - sodium chloride
Like if you imagine making something you create a hypothesis about was to make that happen