MIXTURES Pure SubstancesMatter surrounds us mainly in the form of mixtures. Once we have obtained pure substances out of the But we’ll have to do mixtures, we can go something to obtain : on studying this type of substances to classify and characterize them.
MIXTURES PURE SUBSTANCES Mixture: Made of Pure substance:more than one kind Made of only one of PARTICLE kind of PARTICLE
MIXTUREConsidered from the M1 point ofview, it is made out of more thanone type of particle The composition of a mixture is VARIABLE. Same samples contain different number ofeach of the components o the mixture. It can be recovered by putting the ingredients together. It is easy to separate. It is easy to separate because its components maintain their properties.
MIXTURE COMPOUNDConsidered from the M1 point of Considered from the M1 point of view,view, it is made out of more than it is made out of one type of particle. But from the M2 point of view eachone type of particle particle contains more than one type of atom. The composition of a mixture is VARIABLE. The composition of a Same samples contain different number ofeach of the components o the mixture. It can compound is fixed. We could be recovered by putting the ingredients even give a formula for each together. compound (H2O, NH3). It is easy to separate. It is difficult to separate. It is easy to separate because its It is difficult to separate because, being components maintain their properties a pure substance, we have to break the and we can separate them without particle of the substance. After this breaking the substances the mixture is process the initial substance is not made out of. The initial mixture is normally recovered. normally recovered when mixing again
Heterogeneous Mixtures• Heterogeneous mixture -A mixture in which different materials can be distinguished easilyHeterogeneous: A material which is not uniform at all macroscopic levels and methods of observation.
Homogeneous Mixtures • Homogeneous mixture two or more gaseous, liquid, or solid substances blended evenly throughout.Homogeneous: Uniform at all macroscopic levels and methods of observation
MIXTURE What does this mean? How to consider this variability in a homogeneous mixtureVariablecomposition
HETEROGENEOUS (Even from theMACROSCOPIC point of view) THE COMPOSITIONVARIES DEPENDING ON THE PART OF THE MIXTURE I CONSIDER
HOMOGENEUS - From the MACROSCOPIC point of view HETEROGENEOUS - From the MICROSCOPIC 1 point of view)We know it contains more than one type ofparticle. We also know that it does not havefixed physical and chemical properties.
In this case, the composition will not depend on the part of the mixture we consider! If this is water with salt, both parts of the substance will contain the same proportion of salt particles and water particlesThen, What does VARIABLE COMPOSITION mean?
The composition of themixture can be easily changedby adding more salt or more water. Every time you do this, you obtain a mixture with a different composition and with different properties (density, for instance)
On the contrary, water, aspure substance, has a fixedcomposition, a fixedformula. (H2O)But to undesrtand this factwe have to consider puresubstances from theMICROSCOPIC 2 point of view
MIXTURES Pure SubstancesHOMOGENEOUS HETEROGENEOUS HOMOGENEOUS >1 type of >1 type of 1 type of particle particle particle PHYSICAL COMPOUND ELEMENT Sieving Evaporation Filtration Distillation Decantation Centrifugation CHEMICAL ELECTROLYSIS …. MORE THAN 1 TYPE OF ATOM 1 TYPE OF ATOM H20, CS2, PCl5 H2, S8, O3
MICROSCOPIC 2 POINT OF VIEW : ATOMS .- Atoms is what the particles are made out of! .- There can be different types of atoms in a particle / molecule! .- The unique way in which the atoms are bonded give the particle / molecule its name and properties
WATER MOLECULE H20This is how atoms bond in a water molecule
We will only deal withshorthand formulas forthe different puresubstances.The real 3D structure, whyatoms bond in thisparticular way (and how)is not to be discussed thisyear.
JUST REMEMBER:.- Atoms is what the particles are made out of!.- There can be different types of atoms in aparticle / molecule!.- The unique way in which the atoms arebonded give the particle / molecule its nameand properties
Each element has a name, a symbol and a place in the periodic table.The periodic table is the best way to list the atoms of the different elements. Remember that an element is a pure substance made out of one type of atom.
Apart from the name: Each element has a symbol. For two letter symbols use acapital letter for the first one and a small letter for the second(Ca, Sr, Ba, Ra, Sn, Sb, Sc, Ti, Mg, Mn). Use a capital letter to write one letter symbols (C, S, O, F, H, N, K, B ...)Every PURE chemical substance (element or compound) has a formula that shows the type of atom and the number of each type of atom present in a particle of the substance. The formula does not give any clue about how the atoms are arranged and bonded together.
NUMERICAL SUBSCRIPTS:They must be subscripts and they must bewritten following the symbol they refer to:H2O: 2 atoms of hydrogen and1 atom of oxygen.There is no need to write “1” if there is onlyone atom of this kind)
A group of atoms in brackets means that this groupof atoms is repeated in the molecule (or particle).The subscript that follows the bracket informs usabout how many times this group is repeated. Ca3(PO4)2 3 atoms of calcium. 2 * 1 = 2 atoms of phosphorus. 2 * 4 = 8 atoms of oxygen.
Do we have to learn thecomplete periodic table ???????