How to draw a Lewis Structure

Level 2 exceptions to the octet rule

Shape is determined by

If the central atom is surrounded by four negative regions/electron clouds,
the electrons involved repel each other to a ...

If the central atom is surrounded by three negative regions/electron clouds,
the electrons involved repel each other to a ...

If the central atom is surrounded by two negative regions/electron clouds,
the electrons involved repel each other to a ...

What shapes arise from a tetrahedral arrangement of negative regions?

What is the shape of a molecule with 3 electron clouds
one of which is not involved in bonding?