Chemical Bond and Types of bonds ionic bond or elctrovalent bond

CHEMICAL BONDING 

Definition: The attractive force present between the atoms that holds the atoms together as a molecule is known as “Chemical Bond”
·      1) Why do atoms combine to form a molecule?
·      2) Why do atoms combine in a fixed ratio?
·      3) How can the properties of compounds be understood in term of attractive forces?

CAUSE OF CHEMICAL COMBINATION

·      Tendency to acquire inert gas electronic configuration (ns2np6). Atoms of elements acquire eight electrons in their valence shell by involving in chemical combination is known as “Octet rule”
·      Tendency to acquire minimum energy
1) The atoms are unstable and possess high energy
2) During bond formation energy is released.
This energy is known as bond energy.
3) Bond formation between atoms leads to stability with lesser energy.

OCTET RULE

·      Noble gas elements, except He(1s2), contain 8 electrons in the valence shell. The stability of these elements is due to its octet configuration.
·      Other than Noble gas elements contain less than 8 electrons in the valence shell.
·      Elements try to get octet configuration by means of bond formation
·      Atoms try to get 8 electrons in valence shell either by transfer or sharing of electrons.

TYPES OF BONDS

·      The type of bond formed between atoms depends on the nature of elements. The chemical bonds are
1)Ionic bond or electrovalent bond
2)Covalent bond
3)Metallic bond
4)Hydrogen bond
5)Vanderwaal’s forces 

IONIC BOND OR ELECTROVALENT BOND 

Definition: The electrostatic force of attraction between oppositely charged ions formed by the transfer of electrons is called as “Ionic Bond”. Example: Na+cl-
·      Ionic bond is formed between the atoms of
a) if electro negativity difference is more than 1.73.
b) between a metal with low ionization energy and a non-metal with high electro negativity.
·      Ionic bond formation is explained in 3 steps
i) formation of cation (from metal atom)
ii) formation of anion (from non-metallic atom) and
iii) association of oppositely charged ions due to electrostatic attractive force.

Example: Sodium chloride (NaCl) formation:
·      Sodium metal combines with chlorine gas to form crystalline solid sodium chloride explained in 3 steps .
Electron configuration of sodium is 1s2 2s2 2p6 3s1
(i)It readily loses valency electron and gets the nearest noble gas configuration (2s2 2p6)
·      Positive sodium ion is formed



(ii) Electron configuration of chlorine is 1s2 2s2 2p6 3s2 3p5
·      It gains one electron from sodium to get nearest noble gas configuration (3s2 3p6)
·      Negative chloride ion is formed


  (iii) The oppositely charged Na+ and Cl- ions are held together by electrostatic force of attraction,the ionic bond is formed









Comments

Post a Comment

Popular posts from this blog

English grammar error spotting finding correction exercise Practise set 36

Image
English grammar error spotting correction exercises practice set 36 In the following English grammar error spotting questions, some parts of the sentences have errors and some are correct. Find out which part of a sentence has an error. The number of that part is the answer. If a sentence is free from error, your answer is No error. Question 1: When I left (1)/ the house at 9 o'clock (2)/ my son was still at home. (3)/ No error (4) Answer Answer : (4) No error Question 2: There is (1)/ only one of his novels (2)/ that are interesting (3)/. No error (4). Answer Answer : (3) is will replace are because – when a Plural Noun is placed with a Singular Subject (one, each, etc.) with of, the Verb will be Singular. Look at the example given below : Only one of his employees is sincere at work. Only one of his students is awarded the ‘Scholar award’. Hence, that is interesting is the right usage. Question 3: The hockey match (1)/ between India and Pakistan (2)/ was much exci
All Blog Posts

pneumatic comparator and solex pneumatic comparator

Image
Principle of pneumatic comparator The measurement is made by taking reading using master gauge of known accuracy and comparing with component reading It uses a controlled, pressurised jet of air to measure small dimensional variation in the size of component The working principle of pneumatic comparator depends on the flow of air between the gauge head and the component being checked Important characteristics Very high magnifications are possible It can be used to measure diameters, length, squareness, parallelisms, concentricity,taper, and other geometric conditions. Internal dimensions can be readily measured , in other words, while measuring a bore it can reveal complete details of size, taper, straightness,camber and bell mouth etc. It is independent of the operator skill High pressure air gauging can be done by cleaning the parts which helps to eliminate errors due to dirt and foreign matter. As there is no physical contact made either with the setting gauge (or)
All Blog Posts

interferometer and interferometry

Image
Interferometer Interferometer is an optical device used for measuring flatness of a surface and also for determining the thickness of slip gauges. It is an extension of the application of optical flat. Interferometers are based upon the principle of “ interference “ and employ wavelength of light as their measuring units. The interferometers make use of beam divider that splits an incoming ray into two parts. These two parts of the ray travel along different paths until they are recombined, usually in the same beam divider. An interferometer is an optical device which utilizes the effect of interference. Typically, it starts with some input beam, splits it into two separate beams with some kind of beam splitter (a partially transmissive mirror), possibly exposes some of these beams to some external influences (e.g. some length changes or refractive index changes in a transparent medium), and recombines the beams on another beam splitter. The power or the spatial shape of the resulti
All Blog Posts