I believe you are defining an "atom".
element
The primary substances of which all other things are composed are known as elements.
primary pigment colours.
You can use Chromatography.
The two primary types of homogeneous matter are elements and compounds. Homogeneous matter is a substance that has uniform properties and compositions.
hydrogen
Secondary pollutants are the substances that pollute the air only after they interact with other substance in the Earth's environment. Primary pollutants are injected into the atmosphere directly.
A primary standard substance is referred to a reagent which is pure. This is a substance that can be weighed easily due to its purity.
A primary standard substance is referred to a reagent which is pure. This is a substance that can be weighed easily due to its purity.
The primary substances of which all other things are composed are known as elements.
primary pigment colours.
Water
water/ H2o
The primary determing factor would be the size of the substance
Proteins?
substances that cannot be chemically interconverted or broken down into simpler substances and are primary constituents of matter.
Nicotine and/or caffeine
Diffusion