Matter

Matter

• Anything that occupies space and has mass.
• Is made up of very tiny and discrete particles (atoms, molecules, ions). 
• E.g. the stuffs our universe is made of, be they tangible (earth, trees) or intangible (air).

Elements

• Substances that consist of only one type of atom.
• Cannot be decomposed into simpler substances by chemical means. 
• Are made up of atoms or molecules.

Compounds

• Substances formed from two or more elements that are chemically bonded (covalence or ionic) in fixed proportion by mass.
• The properties of compound differ from the elements that make up the compound, and can only be separated by chemical means into their pure components. 
• Are made up of molecules (covalence bonding) or ions (ionic bonding).

Atoms

• The smallest particle (basic unit) of an element that can take part in a chemical reaction.
• E.g. usually metals (iron, lead, copper, etc.).

Molecules

• A group of two or more atoms that are chemically bonded together by the sharing of valence electrons (covalence) and are electrically neutral.
• Can consist of the same type of atoms (elements) or different types of atoms (compounds). 
• E.g. same type of atoms - element (H₂, O₂, O₃, N₂, etc.).
• E.g. different types of atoms - compound (H₂O, C₆H₁₂O₆, etc.).

Ions

• An atom or a group of atoms that has acquired a net electrical charge by gaining (negatively charged, anion) or losing (positively charged, cation) one or more valence electrons.
• E.g. anion (Cl^-, Br^-, SO₄^2-, etc.). 
• E.g. cation (K⁺, Na⁺, Ca²⁺, H⁺, etc.).