Bacteria.
The smallest bacteria is an organism capable of independent life. Anything smaller than this is not large enough to contain all the "metabolic machinery" necessary for independent life. For example, a virus can be considered to be alive but it is too small to exist independently and must infect a host cell in order to survive.
Atoms
An Atom.
We could say what the second smallest piece of matter if we knew what the smallest piece of matter was. Since the smallest pieces of matter known are quarks-down, strange and bottom have the lowest charge -3, they can be regarded as the first, second and third smallest particles.
The density of the small piece of matter and the large piece of matter is the same because density is a characteristic property of a material and is independent of the amount or size of the material. Density is calculated by dividing the mass of an object by its volume, so as long as the material is the same, the density will remain constant.
The smallest part of any chemical element that can exist is an atom of that element. The smallest part of a chemical compound that can exist is a molecule of that compound.
Democritus called the smallest piece of matter "atoms" because in Greek, "atomos" means indivisible or uncuttable. He believed that all matter was made up of these tiny, indivisible particles that couldn't be divided any further.
He was using this to compare it to the smallest part of an element ... an atom which he called "atomos" from the Greek origin
An atom is the smallest piece of matter that retains the properties of an element. It consists of a nucleus (protons and neutrons) surrounded by electrons. Each element has its own unique type of atom.
Small matter, this can be answered depending on how you look at it, originally atoms were named because they were believed to be the smallest particle of matter and cannot be split anymore but scientists now know that subatomic particles exist such as quarks. They and others are building blocks of matter. http://www.nyu.edu/pages/mathmol/textbook/atoms.html A particle is a very small piece of matter. Particles are part of atoms. Atoms are the smallest unit of all substances.
Small matter, this can be answered depending on how you look at it, originally atoms were named because they were believed to be the smallest particle of matter and cannot be split anymore but scientists now know that subatomic particles exist such as quarks. They and others are building blocks of matter. http://www.nyu.edu/pages/mathmol/textbook/atoms.html A particle is a very small piece of matter. Particles are part of atoms. Atoms are the smallest unit of all substances.
The smallest particle of an element that still has all the properties of an element is an atom of that element.
The term 'particle' broadly encompasses any relatively small piece of matter, but in particle and nuclear physics, quarks and electrons are smallest, followed by protons, then neutrons.