Chapter 6, Problem 16STP

Summary Introduction

To write:

The revision by scientists that atoms were not the smallest part of matter.

Introduction:

Matter is anything that has mass and takes up space. It is composed of tiny particles called atoms. Atoms are the building blocks of matter. The branch of science that deals with the study of matter- its properties and composition is called chemistry.

Explanation of Solution

In the 5th century B.C, two Greek philosophers Leucippus and Democritus first proposed that all matter is made up of tiny, indivisible particles. It was only in the 1800s that scientists began investigating and collecting experimental evidence to support the existence of atoms. Dalton provided evidence of atoms and introduced the atomic theory. However, he thought that atoms are the smallest particles of matter. The discovery of electrons and protons by J.J. Thomson and Rutherford, respectively, proved that atoms are made up of even smaller particles. The smaller particles that make up atoms are protons, neutrons, and electrons. Neutrons are located at the center of the atom called nucleus and have no charge. Protons are positively charged while electrons are negatively charged located outside the nucleus. The number of protons and electrons in an atom are equal so they have an overall charge of zero.

Conclusion

The discovery of the electrons and protons along with nucleus led scientists to revise the definition that atoms exist but they are made up of even smaller particles.