Basic Cocept of Chemistry Part 1

1. TEMPERATURE      Degree of hotness or coldness of a body is called "TEMPERATURE".    "Temperature is a measure of the intensity of heat".    Temperature is defined as:    "The average kinetic energy of the molecules of a body temperature is called" SCALES OF TEMPERATURE:      There are three scales of temperature.    1. Celsius centigrade scale or C.    2. F. Fahrenheit scale    3. Absolute scale or Kelvin K. CONVERSION      Centigrade & Kelvin Tk = Tc + 273    Centigrade & Fahrenheit C / 5 = (F-32) / 9 2. VOLUME      Volume is defined as    "The space occupied by a body is called ITS volume." SYMBOL      Volume is denoted by "V UNITS      a) m3    b) dm3    c) cm3    d) mm3    e) Litre    f) Milli liter 3. MASS      The quantity of matter Contained in a body is called its "Mass". SYMBOL      Mass is denoted by "m". UNITS      a) Kilogram    b) Gram    c) Milligram    d) Microgram 4. DENSITY   Mass per unit volume of a substance is called its "Density". FORMULA   UNIT      a) kg / m3    b) gm / cm3    c) gm / liter    d) gm / dm3 5. MOLE   "Formulated atomic mass or mass or molecular mass of a Expressed in grams substance is called MOLE ". Or Mass of a substance contains 6.02 x 1023 Atoms or molecules or ions is called "mole"    For example:    1. Atomic mass of carbon = 12 a.m.u.    THEREFORE 12 gram of carbon = one mole of carbon.    2. Formula mass of NaCl = 58.5 a.m.u.    THEREFORE 58.5 gm of NaCl = 1 mole of NaCl.    3. Molecular mass of CO = 28 a.m.u.    THEREFORE 28 gm of CO = I mole of CO FORMULA     6. Avogadro's Number      One mole of any substance contains 6.02 x 1023 Atoms, molecules or ions. This number is particularly called "Avogadro's number".    It is denoted by NA.    For Example.    1 mole = 6.02 x 1023 Carbon Carbon Atoms.    Na + 1 mole = 6.02 x 1023 Na + ions.    1 mole = 6.02 x 1023 H2O H2O molecules. 7. LAW OF DEFINITE PROPORTION      STATEMENT    According To the law of definite proportion "Every sample of pure substance always contains same elements in fixed proportion Regardless of Its method of preparation "     EXPLANATION    We can Obtain or water prepared by a number of methods but water from any source Obtained always Contain 11.11% 88.88% hydrogen and oxygen.    Similarly CO2 can be prepared by different methods but each contains sample of CO2 C = O = 27.27% and 72.72%. 8. SPECIFIC GRAVITY      Specific gravity of a substance is defined as the ratio of the mass of substance to the mass of an equal volume of water at temperature owners. FORMULA   Specific gravity = mass of substance / mass of an equal volume of water UNIT      It has no unit. 9. GRAM ATOMIC MASS   "Atomic mass of an element is called Expressed in gram gram atomic mass"    For example:    Gram atomic mass of C = 12gm.    Gram atomic mass of H = 1 gm.    Gram atomic mass of O = 16 gm. 10. GRAM MOLECULAR MASS   "Molecular mass of a molecule Expressed in grams is called gram molecular mass."    For example:    Gram molecular mass of hydrogen gas = 2 gm.    Gram molecular mass of oxygen gas = 32GM.    Gram molecular mass of HCl = 36.5 gm 11. ELEMENT   "Element is defined as a substance in Which puree all the Atoms Have same chemical properties and Have same atomic number "    For example:    Carbon, sodium, hydrogen, chlorine, copper, gold, iron etc. TYPES OF ELEMENTS      Elements can be divided into two classes.    1. Metals.    2. nonmetals. METALS      They Have on Their surface shine.    They are good conductors of electricity and heat.    They Reflect light.    Metals are ductile.    Metals are malleable. EXAMPLE      Cu, Fe, Au, Na, Ca etc. NON-METALS      They Have dull surface.    They are bad conductors of electricity and heat.    Non-metals are non ductile.    They can not be drawn into sheets.    They are brittle.    EXAMPLE    H2, C, Cl2, O2, N2 etc. 12. Valency      Valency is defined as "The combining capacity or combining power of an element With the other element"    In other words valency May be defined as:    the number of H-Atoms combine With or displace Which one atom of an element or a radical is called valency.    EXAMPLES ELEMENT Valency Na, K 1 Ca, Mg 2 F, Cl 1 N 3 13. MOLECULE      The smallest unit of an element or compound, Which can exist Independently, is called "molecule". 14. EMPIRICAL FORMULA   "Empirical Formula Is That Which makes expresses the relative number Atoms of each kind of present in the molecule of a compound " OR "The formulation of a compound Which In Which expresses the ratio of Atoms different elements are combined in a molecule " It indicates empirical formula only atomic ratios but it does not present Indicate Number of Atoms of different kinds present in the molecule of a compound. Two or more compound May Have same empirical formula. Empirical formula is Determined by experiment. EXAMPLE      Empirical Formula of Benzene = CH    Empirical Formula of Glucose = CH2O