Ions are particles (atom or group of atoms) that carry a net positive or negative electrical charge. Positively-charged ions are known as cations. Negatively charged ions are known as anions.   Atoms tend to gain or lose electrons in order to achieve a stable electronic structure. Atoms are stable when they have a fully filled […]

An ionic compound is a chemical compound made up of cations (positively-charged ions) & anions (negatively-charged ions). In the solid state of an ionic compound, the cations & anions are held together by ionic bonds (electrostatic forces of attraction) in a lattice structure. Examples of ionic compounds: sodium chloride – NaCl, sodium fluoride – NaF, […]

A molecular compound (also known as a covalent compound) is a chemical compound made up of molecules that consist of two or more atoms of different elements. The atoms in the molecules of a molecular compound are held together by covalent bonds (sharing of electrons). The molecules in a molecular compound are held together by […]

This video gives detail explanation on the difference between ionic compounds & molecular compounds (covalent compounds).

The smallest repeating unit of an ionic compound is known as a formula unit. A formula unit is made up of a cation & an anion. Example: the formula unit of sodium chloride is NaCl; the formula unit of calcium chloride is CaCl2 The chemical formula (empirical formula) of an ionic compound shows the simplest […]

This video shows you the difference between molecules of molecular compound & formula units of ionic compound.

The relative atomic mass of an element is the average mass of one atom of the element when compared with one twelfth of the mass of a carbon-12 atom. Relative atomic mass has no unit.    

The relative molecular mass of a substance is the average mass of a molecule of the substance when compared with one twelfth of the mass of a carbon-12 atom.   Relative molecular mass has no unit.

Definition of mole: One mole of a substance is defined as the amount of substance that contains the same number of particles as in 12 g of carbon-12.   Don’t get confused by this definition. It basically means: One mole of carbon-12 = 6.02 x 1023 particles in carbon-12 = 12 g per mole (molar […]

One mole of a substance contains 6.02 × 1023 particles in the substance. The number of particles in one mole of a substance is known as the Avogadro constant (also known as Avogadro’s number). *The unit of Avogadro constant is particles per mole (particles mol-1)

Depending on the type of substance, the particles in the substance can be atoms, molecules, or formula units.   For atomic substance, the particles in the substance are atoms. *One mole of atomic substance contains 6.02 x 1023 atoms. Example:   1 mole of iron contains 6.02 x 1023 Fe atoms.   For molecular substance, […]

Remember this formula:   Avogadro constant = 6.02 x 1023 particles per mole. Therefore:   This formula shows you how to calculate: 1)      The number of particles (atoms, molecules or ions) when the number of mole is given. 2)      The number of mole when the number of particles (atoms, molecules or ions) is given.