ATOMS 4U

Generally we know that atomic size increases down the group from top to bottom due to increase in the number of valance shell . But then why the atomic size of gallium is less than aluminum ?  Because , in case of gallium due to presence of d-orbitals , size of gallium  decreases to greater extend . D orbitals have poor shielding effect . It means that they cannot shield the nuclear force on outer most electrons. Due to decrease in shielding effect and increase in nuclear force , size of Gallium becomes  smaller than Aluminum . But remember that , this case only for Gallium , remaining 4th period elements follow the same trend , that is atomic size increase down the group . Effects of decrease in size of Gallium  ●Increase in ionization enthalpy  Due to decrease in size of Gallium , it's Ionization enthalpy increases . Smaller the size , more will be nuclear force on valance electrons . Therefore more energy requires to remove electron from the outermost shell . That why Ionization

Solubility of a molecule or substance in water depends on the formation of bonds  between then water and a molecule .  Ortho-nitrophenol (o-nitrophenol) molecule forms intramolecular bonds with itself . Intramolecular bond means bonding within the molecule .This leds to no free -OH bond available for Hydrogen bond formation . Due to this , there is less bonding between water and o-nitrophenol  On the other hands , para-nitrophenol(o-nitrophenol ) has a free -OH bond and can form strong intermolecular hydrogen bonding with water Molecules . Due to this they are more soluble in water . So , in short p-nitrophenol is more soluble than o-nitrophenol due to strong intermolecular hydrogen bonding

Electron gain enthalpy is the enthalpy Change take place when an electron is added to isolated gaseous atom . Electron gain enthalpy of halogens are highly negative because this process is exothermic in nature and large amount of heat is released . Fluorine is most electronegative element in the periodic table still it's  electron gain enthalpy is less than  Chlorine . Why Chlorine has High electron gain enthalpy than Flourine ? Size of fluorine is very small . So when an extra electron tries to attract toward this atom , their is large electron - electron repulsion take place between the outermost electrons and incoming electron . It becomes difficult for incoming electron to add up in the outermost shell . On the other hand , Chlorine is larger in size than flourine and when extra electron come in contact with this atom , Chlorine immediately tries to attract toward itself . Due to larger size , their is less electron - electron repulsion and it becomes easier for an

Solid is a rigid and incompressible state of matter . Due to high intermolecular forces and less intermolecular distance ,they are very difficult to compress . They have a definite shape and definite volume . Solids are broadly classified into two types 1. Crystalline Solids 2. Amorphous Solids 1. Crystalline Solids   ●Solids in which the constituent particles are arranged in a definite and regular pattern is called as Crystalline Solids. ●They have long range order.  It means that the regularity in the arrangement of particles is up to long ranges ● They have sharp melting point . They do not melt at any temperature . When a particular temperature reached they start melting.  ● They are anisotropic in nature. It is a property of crystalline Solids to show different properties in different directions is called as anisotropy .  Crystalline Solids can be isomorphous or polymorphous . Isomorphous ●Two or more Substances having same Crystalline structures are called as isomorph

Matter is anything that has a mass and occupy space . Ice  , pen , pencil ,dog , etc are examples of matter because they have some mass and they occupy space . There are basically three states of matter , ●Solid  ●Liquid ●Gas Solid   Solid is defined as rigid and incompressible state of matter .  Now the question is , why Solids are rigid and incompressible ? To answer this question , let's understand the properties of solids .  1.Solids have large intermolecular force of attraction . Intermolecular force is the force of attraction between to adjacent Molecules .  Higher the intermolecular force , more tightly they will attract each other and less movement of Molecules will occur . 2.Intermolecular distance in Solid is very less . Intermolecular distance is the distance between two adjacent molecules . Less the distance more will the intermolecular force of attraction . Intermolecular force is inversely proportional to intermolecular distance . 3.They have definite shap

Temperature measures the degree of hotness or coldness of an object . Heat always flow from high temperature to low temperature . The point is how to measure this temperature . There are basically three scales use to measure the temperature of an object ●Celsius ●Fahrenheit ●Kelvin Celsius is most widely used scale to measure temperature if an object . Fahrenheit scale is mostly used in United states of America (USA) .  How to convert Fahrenheit to Celsius ? Conversion of Fahrenheit scale to Celsius is very easy task , let's see how it works . Relation between Fahrenheit and Celsius , C = (F - 32 ) × 5/9  Here C - temperature in Celsius F - temperature in Fahrenheit Examples : 1. F = 32 , then    C = ( 32 - 32 ) X 5/9     C = 0 ℃ 2. F = 212      C = ( 212 - 32 ) X 5/9     C = 100 ℃ 3. F = 266 C = ( 266 -32 ) X 5/9 C = 130 ℃ In this way you can easily convert Celsius and Fahrenheit reading .