Elements, Compounds and Mixtures

Made by: M. Fahd-Un-Nabi KhanUSMAN PUBLIC SCHOOL

XI-O

ElementsAn element is a substance which cannot be

split into two or more substances by chemical means

The smallest possible particle of an Element that can take part in a chemical change is called an ATOM.

CompoundsCompound is substance containing 2 or more

elements chemically joined together. e.g. Magnesium is an element; oxygen is

an element – they can only be combusted to form magnesium oxide (MgO) compound.

Ions or molecules make up compounds Ions are atoms having electrical charge, e.g.

NaCl made up of 2 ions; positively charged Na, negatively charged Cl.

MoleculesMolecule is group of two or more atoms

chemically joined together, e.g. chlorine molecule has 2 chlorine atoms.

Molecules can be either ELEMENTS or COMPOUNDS.

E.g. MgO is a compound, but Cl2 is an element

Mixtures 2 or more substances which are not chemicall

y joined together e.g. Iron in Sulphur powder. Can consist of:  

Elements   (Iron & Sulphur powder) Compounds (Salt in water

- salt & water are bothcompounds) 

Elements + Compounds   (Air; N2, O2, H2O) 

Difference between Compounds and MixturesMIXTURE COMPOUNDS

Constituent substances can be separated easily by physical means

Its physical and chemical properties are an average of substances in it

A mixture’s proportion can vary

Little or no energy is involved when Mixture is formed

Constituent substances can be separated only by chemical means

Its physical and chemical properties are individual and not the result of its elements

A compound’s proportion cannot vary

Energy is usually involved when a Compound is formed

Diffrentiation between Pure and MixturesPure Substances (elements, compounds) 

1) Fixed composition 2) Fixed Mp/Bp 3) Produces only 1 spot on chromatogram 4) All molecules same (equal) 

Mixture 1) Variable Composition 2) Variable Bp/Mp 3) 2 or more spots on Chromatogram 4) 2 or more different molecules