Halide-main group elements

-
The alkali metals combine directly with halogens under appropriate conditions forming halides of the general formula, MX (X = F, Cl, Br or I).
A halide ion is a halogen atom bearing a negative charge. The halide anions are fluoride (F−), chloride (Cl−), bromide (Br−), iodide (I−) and astatide (At−). Such ions are present in all ionic halide salts. Halide minerals contain halides.
All these halides are colourless, high melting crystalline solids having high negative enthalpies of formation. 
Halide compounds such as KCl, KBr and KI can be tested with silver nitrate solution, AgNO3. The halogen will react with Ag+ and form a precipitate, with varying colour depending on the halogen:
  • AgF: no precipitate
  • AgCl: white
  • AgBr: creamy (pale yellow)
  • AgI: green (yellow)
For organic compounds containing halides, the Beilstein test is used. 
Different reaction;-



Comments

Post a Comment

Popular posts from this blog

Structures of AX,AX2 and ABX3 type compounds

-
Image
The simple structures come from the arrangement of the anions (though sometimes the cations) in the positions of the spheres in the fcc or hcp lattices, and the cations go into some or all of the octahedral and tetrahedral holes within the lattices. Structures based on face centered cubic lattices The Rock Salt structure This the structure adopted by  Sodium Chloride , NaCl. It is based on the fcc array of the large chloride anions, and the sodium cations occupy all the octahedral holes in the fcc  lattice . However, it could also be seen as an fcc array of sodium ions, with the anions in all the octahedral holes. Each ion is octahedrally coordinated by six counterions, and so this structure has so-called  (6,6)-coordination , where the first number refers to the coordination of the  cation  and the second to the  anion . The structure beyond the first coordination sphere can also be visualized. The Rock Salt, or NaCl, structure The sodium cations (green) occupy the oct
Read more

Miller planes

-
Image
Planes in a crystal are described by notations called Miller indices  Miller indices of a plane, indicated by h k l, are given by the reciprocal of the intercepts of the plane on the three axes.  The plane, which intersects X axis at 1 (one lattice parameter) and is parallel to Y and Z axes, has Miller indices h = 1/1 = 1, k = 1/ = 0, l = 1/ = 0. It is written as (hkl) = (100).  Crystal Planes To find the Miller Indices of a plane, follow these steps:  Determine the intercepts of the plane along the crystal axes  Take the reciprocals  Clear fractions  Reduce to lowest terms and enclose in brackets () Ex: Intercepts on a, b, c : ¾, ½, ¼ (h k l) = (4/3, 2, 4) = (2 3 6) Planes can also have negative intercept e.g. 1, -1/2, 1 h k l = 1 -2 1. This is denoted as ( ) 121  Family of planes {hkl}  Planes having similar indices are equivalent, e.g. faces of the cube (100), (010) and (001). This is termed as a family of planes and denoted as {100} which includes all th
Read more

Oxide-Main group elements

-
Image
Oxides are chemical compounds with one or more oxygen  atoms combined with another element (e.g. Li 2 O). Oxides are binary compounds of oxygen with another element, e.g., CO 2 , SO 2 , CaO, CO, ZnO, BaO 2 , H 2 O, etc. These are termed as oxides because here, oxygen is in combination with only one element. Based on their acid-base characteristics oxides are classified as acidic, basic, amphoteric or neutral: An oxide that combines with water to give an acid is termed as an acidic oxide. The oxide that gives a base in water is known as a basic oxide. An amphoteric solution is a substance that can chemically react as either acid or base. However, it is also possible for an oxide to be neither acidic nor basic, but is a neutral oxide. Defferent type of oxides;- Acidic Oxides Acidic oxides are the oxides of non-metals ( Groups 14-17 ) and these  acid anhydrides form acids with water: Sulfurous Acid SO 2 + H 2 O → H 2 SO 3 (1.1) (1.1) SO 2 + H 2 O → H 2
Read more