![]() Here is the above diagram drawn slightly different.Īs you can see, you can ask right away whether matter’s composition is uniform and constant throughout. And this pure substance can either be an element or a compound. Notice from the model that a mixture like sugar solution can be homogeneous, but not a pure substance. If you determine that its composition is fixed, then it is a pure substance. However, if it is homogeneous, then it can either be a pure substance or a homogenous mixture. If it is heterogeneous, then right away it is a heterogeneous mixture. Here is a model showing how matter can be classified by composition.įrom the flow diagram, a piece of matter is examined to determine whether it is homogeneous or heterogenous. When matter is a pure substance, it can either be a compound or an element. ![]() When matter is a mixture, it can either be homogeneous or heterogeneous mixture. Matter can be classified as mixture or pure substance. Why’s it that in gases the molecules are widely spaced?īecause the kinetic energy of the molecules is much stronger than the attractive forces between. Why’s it that in liquids the molecules are loosely packed?īecause the kinetic energy of molecules is slightly stronger than the attractive forces between them. Why’s it that in solids the molecules are tightly packed?īecause the attractive forces between the molecules are much stronger than their kinetic energy. gases the molecules are widely spaced, as a result, they can move about much more random.liquids the molecules are not closely packed as in solids, as a result, they can move around much more than the molecules in solids.solids the molecules are closely packed, as a result, they can only vibrate from their fixed positions.Here is a model showing the three states Classifying matter by stateįrom the particle models, you can see that for: Matter can exists as solid, liquid or gas. Composition How to classify matter by state.Properties How can Matter be Classified?.The valence orbitals of an atom surrounded by a tetrahedral arrangement of bonding pairs and lone pairs consist of a set of four sp 3 hybrid orbital. A lone pair, an unpaired electron, a single bond, or a multiple bond would each count as one region of electron density. As we know from the discussion of VSEPR theory, a region of electron density contains all of the electrons that point in one direction. The central atom(s) in each of the structures shown contain three regions of electron density and are sp2 hybridized. Valence bond theory would predict that the two \ce.įigure 7.5.9. ![]() Oxygen has the electron configuration 1 s 22 s 22 p 4, with two unpaired electrons (one in each of the two 2p orbitals). As an example, let us consider the water molecule, in which we have one oxygen atom bonding to two hydrogen atoms. However, to understand how molecules with more than two atoms form stable bonds, we require a more detailed model. Thinking in terms of overlapping atomic orbitals is one way for us to explain how chemical bonds form in diatomic molecules. This is not consistent with experimental evidence. The hypothetical overlap of two of the 2p orbitals on an oxygen atom (red) with the 1s orbitals of two hydrogen atoms (blue) would produce a bond angle of 90°. ![]()
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