<em>Answer:</em>
<em>Chemical properties:</em>
Those properties which change the chemical nature of matter.
<em>Example:</em>
- Heat of combustion
- Enthalpy of formation
<em>Physical properties:</em>
Those properties which do not change the chemical nature of matter.
<em>Example</em>
<em>Differences between chemical and physical properties:</em>
Chemical properties Physical properties
1. Observed after the change bringing 1. Observed with out being
the change change
2. These changes the molecules 2. only change physical state
3. Chemical identity changes 3.Chemical identity not changes
4. Structure of material changes 4.Structure of material not change
5. Chemical reaction is needed 5. No need of Chemical reaction
6. depend on composition 6. Does not depend on composition
Answer:
The structures shown by dots and lines to give the exact number of electrons in the outer most shell is explained by Lewis Structures.
Explanation:
Lewis structures are those structures in which the diagram is shown using the electron representation. They are easy to understand as the diagram completely depicts where the electrons are shared and where they are transferred. The diagram also explains where there is a single bond and where there is a di covalent bond or tri covalent bond explaining where the single , double or triple electron pair is shared. The electrons are shown by dots or lines.
For example CCl₄ can be shown as follows
..
.. Cl..
.. ..
..Cl..----------C----------..Cl..
..
.. Cl..
The picture shows that each chlorine has six electrons in its outer shell and then a pair of electron is shared with carbon forming a single covalent bond.
Similarly methane CH4 can also be shown.
The hydrogen has one electron and it shares an electron from carbon stabilising itself forming methane.
