Second only to oxygen, silicon is the most abundant element in Earth's crust. It is found in rocks, sand, clays and soils, combined with either oxygen as silicon dioxide, or with oxygen and other elements as silicates.
Gravity is a force that attracts objects. It is also the force that makes objects fall down when you drop them. Because of gravity things on earth have a certain weight. Gravity on Earth pulls objects to the centre of the planet. Every time you throw a ball up into the air it is pulled back to Earth. This occurs in nature all the time.
Gravity pulls it back down...no. The pressure that your hand exerted on the ball decreases as the sub-atomic pressure on the other sides of the ball overcomes the pressure exerted on the ball. With the pressure being less on one side, the other sides are being pushed in that direction (towards earth).