When moving across the periodic table from Li to Be to B, the first ionization energy increases from Li to Be, then drops for B. The first ionization energy of B is greater than that of Li. Explain why.

• When moving across a period on the periodic table, the value of the effective nuclear charge increases with atomic number. This causes a general increase from Li to Be to B. 
• The even higher value of Be (greater than B) is due to the increased stability of the electron configuration of Be. 
• Beryllium has a filled s-subshell. Filled subshells have an increased stability, and additional energy is required to pull an electron away. 

What is the uses of iodine?

• A solution containing potassium iodide (KI) and iodine in alcohol is used to disinfect external wounds. Elemental iodine is also used as a disinfectant. 
• Silver iodide is used in photography. 
• Iodine is sometimes added to table salt to prevent thyroid disease. 
• Iodine’s other uses include catalysts, animal feeds and printing inks and dyes. 
• Iodine is used in many household cleaning products available from well-known supermarkets. 
• The health benefits of iodine include the formation of healthy and shiny skin, teeth, and hair. It is an important element for hair care, as lack of this mineral can result in hair loss. Moreover, it also speeds up hair growth and increases follicle strength. 
• Iodine influences the functioning of thyroid glands by assisting in the production of hormones, which are directly responsible for controlling the body’s base metabolic rate.  
• Iodine plays an important role in maintaining optimal energy levels of the body by ensuring the efficient utilization of calories, without allowing them to be deposited as excess fats. 
• A sufficient quantity of iodine in pregnant women is essential to prevent stillbirths or neurocognitive conditions like cretinism in the newborn babies.  

What is the uses of chlorine?

• Chlorine is used for producing safe drinking water and treat swimming pool water. Chlorine kills bacteria – it is a disinfectant.  
• It is also used to make hundreds of consumer products from paper to paints, and from textiles to insecticides. 
•  About 20% of chlorine produced is used to make PVC. This is a very versatile plastic used in window frames, car interiors, electrical wiring insulation, water pipes, blood bags and vinyl flooring. 
•  Another major use for chlorine is in organic chemistry. It is used as an oxidising agent and in substitution reactions.  
• Chlorine is also used for the manufacture of chlorates and it is important in organic chemistry, forming compounds such as chloroform, carbon tetrachloride, polyvinyl chloride, and synthetic rubber. 

What is the uses of fluorine?

• Fluorine is a highly reactive element that is used in processing nuclear fuel, in producing plastics and as a glass etching solution.   
• It can also be found in toothpaste and drinking water, which help prevent dental cavities and it is a component in air conditioning and refrigeration.  
• Because of its highly explosive nature, it is also used in rocket fuels. 
• Fluorine is used to refine uranium, which is used in nuclear reactors. 
• Fluorine is a component of chlorofluorocarbons. Chlorofluorocarbons were used as refrigerants in air conditioning units and freezers until they were banned because of their contribution to ozone depletion. 
• Fluorochemicals, including many high-temperature plastics such as Teflon, are also made using fluorine. 
• Hydrofluoric acid can dissolve glass and is used to etch the glass in light bulbs and in other products. 

What are the important of hydrogen in life?

• The largest use of hydrogen in the world is in ammonia manufacture. 
• The major application of hydrogen is in the catalytic hydrogenation of organic compounds. Unsaturated vegetable and animal oils and fats are hydrogenated to make margarine and vegetable shortening. 
• Hydrogen is used to reduce aldehydes, fatty acids, and esters to the corresponding alcohols. 
• Hydrogen is important because it is involved in the process of enzyme catalysis and because it stabilizes things like nucleic acids and proteins.  
• Hydrogen is important because it offers Earth another fuel source and may free the Earth from using fossil fuels someday.  
• It is currently used as a gas and liquid for many different industries and is often used to provide electricity in the fuel cells of automobiles or in internal combustion engines. For example, NASA used hydrogen to power the space shuttles. 
• Hydrogen has been used as a primary rocket fuel for combustion with oxygen or fluorine and is favoured as a propellant for nuclear-powered rockets and space vehicles. 
• Liquid hydrogen is used in the laboratory to produce low temperatures. 
• Hydrogen is important because it offers Earth another fuel source and may free the Earth from using fossil fuels someday.  

What is the difference Between Molarity and Normality?

Molarity is the number of moles of solute per liter of solution (common measurement of chemical concentration), while normality is the measure of concentration equal to the gram equivalent weight per liter of solution. Normality and molarity are both measures of concentration in chemical solutions. 

For example,  

A 1 M solution of H2SO4 contains 1 mole of H2SO4 per liter of solution. H2SO4 dissociates into H+ and SO4- ions in water. For every mole of H2SO4 that dissociates in solution, 2 moles of H+ and 1 mole of SO4- ions are formed. This is where normality is generally used. 

A 1 M H2SO4 solution will have a normality (N) of 2 N because 2 moles of H+ ions are present per liter of solution. 

N = M*n 

where n is the number of equivalents 

What is the common uses of methane?

• Methane is the main component of natural gas.  It’s a common fabric, plastic, anti-freeze and fertilizer ingredient.  
• Some consumers use the methane in natural gas as a source of energy while cooking. Others use it to heat and cool their homes. 
• Through a process called distributed generation, the methane in natural gas can create electricity.  
• Methane reacts at high temperatures with steam to yield the hydrogen used in the manufacturing of explosives and ammonia-based fertilizers. 
• Chemical reactions with this compound also yield carbon tetrachloride, methanol, chloroform and carbon black. Carbon black is used in the rubber of tires as a reinforcing agent. Chloroform is utilized in applications such as coolant and spot remover. Carbon tetrachloride is the active ingredient in fire extinguishers. 
• Other valuable chemicals derived from methane include methanol, chloroform, carbon tetrachloride, and nitromethane. The incomplete combustion of methane yields carbon black, which is widely used as a reinforcing agent in rubber used for automobile tires.