Elements, compounds and mixtures
-
Upload
muhammad-fahd-un-nabi-khan -
Category
Documents
-
view
1.819 -
download
0
description
Transcript of Elements, compounds and mixtures
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