Step Up Chemistry

Close Packed Structures In solids, the constituent particles are close-packed, leaving the minimum vacant space. (a) Close Packing in One Dimension In close packing one dimension, spheres are arranged in a row such that adjacent atoms are in contact with each other.  (b) Close packing in Two Dimensions In two-dimensional close packing, a row of closed packed spheres is stacked to obtain a two-dimensional pattern. This stacking is done in two ways: Square close packing and Hexagonal close packing   Square close packing or AAA... Type arrangement - The spheres of second row are exactly above those of the first row. The second row is exactly same as the first one. If we label the first row as A, the second row is also A. Similarly, we may place more rows to get AAA… type arrangement. In this arrangement, the spheres are found to form squares. This type of packing is known as square close packing in two dimensions. Hexagonal close-packing or ABABA… Type arrangement - The spheres in the se

  Substances in which there is a single bond between two carbon atoms. These are called alkanes. Structure of alkanes: Substances in which there is a double bond between two carbon atoms. These are called alkenes. Structure of alkenes: Substances in which there is a triple bond between two carbon atoms. These are called alkynes. Structure of alkynes:                                                               1-Butyne                                                            2- Butyne   This is how we memorise!! If you like my work, you can buy me a coffee.   

  Electrons are negatively charged particles whereas protons are positively charged particles.   Electrophiles are electron loving chemical species. Electrophiles may be either positively charged or neutral species. Electrophile examples: H ⊕ , Cl ⊕ , Br ⊕ , CH 3 ⊕ , SO3, BF3 Electrophiles have a lack of electrons so they are capable of accepting or taking electrons from electron rich species. Electrophiles accept electrons and hence behave as Lewis acids.   Nucleophiles are nucleus loving chemical species. Nucleophiles may be either negatively charged or neutral species. Nucleophile examples: Cl ⊝ , Br ⊝ , CH 3 ⊝ , OH ⊝ , NH 2 ⊝ , H2O, NH Nucleophiles have an excess of electrons so they are capable of donating or giving electrons to electron deficient species.  Nucleophiles donate electrons and hence behave as Lewis bases. Electrophile taking electrons from nucleophile :P “Milagros pueden suceder.” “Miracles can happen.”

Entropy is a measure of disorder or randomness of a system. The term order means presence of symmetry whereas disorder means lack of symmetry.                                                                              Entropy (or disorder) is all around you. Cells within your body are dying, the floor is getting dusty, conflicts are taking place around the world, cars are prone to rusting, etc. The entire universe is marching towards chaos or disorder. This suggests that the entropy (or disorder) of the universe is always increasing. Energy or work must be put into the system, in order to bring the system back to a state of order because a state of order leads to stability whereas disorder leads to instability or chaos.  For example, cars are prone to rusting, therefore, a car must be maintained with work in order to keep it in an ordered state to prevent rusting.  The greater the disorder in a system, the higher is the entropy.   For a given substance, the solid state is

  Energy exists in many different forms. The different types of energy include light energy, heat energy, chemical energy, sound energy, etc. Each form can be converted or changed into other forms. For example, when you burn a piece of wood, the chemical energy stored in the wood changes to heat and light energy. The branch of science which deals with the study of different forms of energy and the relationships between them is known as Thermodynamics.   TERMS USED IN THERMODYNAMICS:      SYSTEM AND SURROUNDINGS When a reaction occurs in a jar, everything inside the jar is the system and everything outside the jar is the surroundings.                                        The part of the universe which is kept under observation is known as the System and the remaining portion of the universe is called Surroundings.     WORK Work is said to be done when an object moves as a result of force (push or pull) applied to it.                                      

    “The meaningful digits which are known with certainty in a measurement are called  significant figures .” Significant figures of a measurement are decided by following rules-   (1) All non-zero digits are considered to be significant figures. For example, if the length of a pencil is measured to be 5.32 cm.  Then, there are in all 3 significant figures in the measurement.   (2) All zeroes between two non-zero digits are considered to be significant figures. For example, in 2.06, there are in all 3 significant figures.   (3) All zeroes after a non-zero digit are considered to be significant figures. For example, in 2.00, there are in all 3 significant figures.   (4) All zeroes coming before a non-zero digit are not considered to be significant figures. For example, in 0.0023, there are only 2 significant figures.   (5) If a number is represented as scientific notation i.e. in the power of 10 then  the significant figure is decided by the co-efficient of the number. For example, in