MOLAR MASS

The molar mass of a substance is its relative molecular mass expressed in grams per mole.

RELATIVE ATOMIC MASS

The relative atomic mass of an element or compound is the number of times the average mass of one atom of that element is heavier than one-twelfth the mass of one atom of carbon-12.

RELATIVE MOLECULAR MASS

The relative molecular mass of an element or compound, is the number of times the average mass of one molecule of it is heavier than one-twelfth the mass of one atom of carbon-12.

The relative molecular mass of an element, is the sum of the relative atomic masses of all the atoms in one molecule of that substance. It is also referred to as the formula mass, this is a more general term.

Note that the relative molecular mass refers only to the relative mass of a molecule.  The formula mass refers not only to the relative mass of a molecule,  but also that of an ion, radical,  electron or any other specified groups or nuclear particles.

RADICALS

A radical is a group of atoms that functions as a single unit in chemical reactions.

PARTICULATE NATURE OF MATTER

Matter is made up of discrete particles, the most widely known ones being atoms, molecules and ions.

WHAT IS AN ION?

An ion is an atom or group of atoms which possess an electric charge.

There are two types of ions: the positively charged ion known as cations, and the negatively charged ions known as anions.

Ions are represented by formulae.

ATOMICITY OF AN ELEMENT

The atomicity of an element is the number of atoms in each molecule of an element.

This number is usually small. Example is in oxygen and chlorine, they are diatomic, meaning their molecules have two atoms, and sulphur and phosphorus exists as polyatomic molecules.

WHAT IS AN ATOM?

The word ATOM from ancient Greek means indivisible. It is used to describe the smallest particle of any substance. It is considered to be the basic unit of simple substances or elements.

An atom is the smallest particle of an element which can take part in a chemical reaction. It is the smallest part of an element that can exist, and still possess the chemical properties of that element.

All atoms are represented by symbols.

WHAT IS A MOLECULE

A molecule is the smallest particle of a substance that can normally exist alone and still retain the chemical properties of that substance.

It is the smallest particle of an element that can exist in free state.

All molecules are represented by formulae.

DIFFERENCE BETWEEN ATOMS AND MOLECULES

Most atoms of the same elements or different elements cannot exist alone, so they bond together with other atoms to form molecules, to exist alone.

LAWS OF CHEMICAL COMPOSITION

There are four laws of chemical combination, which will be stated here in this post. They include:

1). THE LAW OF CONSERVATION OF MASS: this law states that matter can neither be created nor destroyed,  but changes from one form to another.

2). THE LAW OF DEFINITE PROPORTION S: this law is also known as the law of constant composition.  It states that all pure samples of a particular chemical compound, contain the same elements combined in the same proportion by mass.

3). THE LAW OF MULTIPLE PROPORTIONS: this law states that if two elements A and B combine to form more than one compound, then the various masses of one element A, which combines with the fixed mass of the other element B, are in simple multiple ratio.

4). THE LAW OF RECIPROCAL PROPORTIONS: it states that the masses of several elements A, B, C, which combines separately with the fixed mass of another element D are the same as or simple multiples of the masses in which A, B, C themselves combine with one another.