Question

what force helps protons and neutrons to stay at the center of the atom?

Answer 1

In your own words, explain how Rutherford's theory of atoms helped in the development of the modern atomic theory.

Answer 2

Protons and neutrons (collectively called "nucleons") are held together by the strong nuclear force. And I mean "held together" in both senses. The strong force is responsible for binding the quarks that make up nucleons as well as binding the nucleons to each other to make a nucleus.

I'm pretty sure Rutherford showed that atoms were composed of a 'cloud' of negative charge (electrons) surrounding a small, dense, positively-charged centre (the nucleus). Before that people thought atoms were composed of negative charges interspersed in some sort of positively charged material.

Answer 3

Rutherford model dismissed the Plum pudding model.

http://en.wikipedia.org/wiki/Plum_pudding_model