Fluorine

 Fluorine

<---Oxygen       Neon--->

Symbol: F Atomic Number: 9 Atomic Weight: 18.998 Classification: Halogen Phase at Room Temperature: Gas Density: 1.696 g/L @ 0°C Melting Point: -219.62°C, -363.32°F Boiling Point: -188.12°C, -306.62°F Discovered by: Henri Moissan in 1886

Fluorine is the first element in the group of halogens which occupies the 17th column of the periodic table. Fluorine atoms have 9 electrons and 9 protons. It is a fairly rare element in the universe, but is the thirteenth most common element in the Earth's crust.

Characteristics and Properties

Fluorine's most notable characteristic is that it is the most reactive of all the elements. This makes it dangerous and difficult to handle. It will react with nearly every other element. It is also the most electronegative of the elements, meaning that it attracts electrons towards itself.

In standard conditions fluorine forms a gas made up of two fluorine atoms called a diatomic gas. It is pale greenish-yellow in color with a pungent odor.

Fluorine is toxic for humans and very corrosive. Many of the reactions with fluorine are sudden and explosive. Fluorine will burn all sorts of compounds and elements including water, copper, gold, and steel.

Where is fluorine found on Earth?

Because it is so reactive, fluorine does not occur as a free element in nature. It is readily found in minerals in the Earth's crust including fluorspar, fluorapatite, and cryolite. The main source of commercial fluorine is fluorspar (which is also called fluorite). The majority of the world's fluorspar is supplied by China and Mexico.

How is fluorine used today?

Fluorine is rarely used in its pure form, but many compounds of fluorine are used by industry.

One of the most popular applications of fluorine is for refrigerant gases. For many years Chlorofluorocarbons (CFCs) were used for freezers and air conditioners. Today they have been banned because they damage the ozone layer. Many of the replacement gases still contain fluorine, however.

Another application is fluoride. Fluoride is a reduced form of fluorine when bonded to another element. Fluoride is helpful in preventing tooth decay and is used in tap water and toothpaste.

Other applications that use fluorine include high temperature plastics such as Teflon, the smelting of iron and metal production, pharmaceuticals, etching glass, and in processing nuclear fuel.

How was it discovered?

Although other chemists had suspected the presence of an unknown element in the compound fluoric acid, it was French chemist Henri Moissan who first successfully isolated the element in 1886.

Where did fluorine get its name?

The name fluorine is derived from the mineral fluorite which comes from the Latin word "fluere" meaning "to flow." The name was suggested by English chemist Sir Humphry Davy.

Isotopes

Fluorine has one stable isotope, fluorine-19. It is the only form that fluorine occurs in naturally.

Interesting Facts about Fluorine

• Hydrofluoric acid is extremely dangerous and can be fatal.
• Henri Moissan was awarded the Nobel Prize in 1906 for his discovery.
• It is found in the gemstone topaz.
• CFCs were once used as propellant in aerosol spray cans.
• The bond formed between carbon and fluorine to make fluorocarbons is the strongest bond in organic chemistry and is very stable.
• Cesium is sometimes called fluorine's opposite element because it is the least electronegative element.

Chlorine

 Chlorine

<---Sulfur       Argon--->

Symbol: Cl Atomic Number: 17 Atomic Weight: 35.45 Classification: Halogen Phase at Room Temperature: Gas Density: 3.2 g/L @ 0°C Melting Point: -101.5°C, -150.7°F Boiling Point: -34.04°C, -29.27°F Discovered by: Carl Wilhelm Scheele produced the gas in 1774, but it was Sir Humphry Davy who first called it an element and named it chlorine in 1810

Chlorine is the second element in the seventeenth column of the periodic table. It is classified as a member of the halogen group. It has 17 electrons and 17 protons with 7 valence electrons in the outer shell. It is about the twentieth most abundant element in the Earth's crust.

Characteristics and Properties

Under standard conditions chlorine is a gas that forms diatomic molecules. This means that two chlorine atoms join together to form Cl₂. Chlorine gas is greenish yellow, has a very strong odor (it smells like bleach), and is poisonous to humans. High concentrations of chlorine gas can be fatal.

Chlorine is very reactive and, as a result, is not found in its free form in nature, but only in compounds with other elements. It will dissolve in water, but will also react with water as it dissolves. Chlorine will react with all the other elements except the noble gases.

Most common chlorine compounds are called chlorides, but it also forms compounds with oxygen called chlorine oxides.

Where is chlorine found on Earth?

Chlorine can be found in abundance in both the Earth's crust and in ocean water. In the ocean, chlorine is found as part of the compound sodium chloride (NaCl), also known as table salt. In the Earth's crust, the most common minerals containing chlorine include halite (NaCl), carnallite, and sylvite (KCl).

How is chlorine used today?

Chlorine is one of the most important chemicals used by industry. Tens of billions of pounds of chlorine are produced each year in the United States alone for use in industrial applications. It is used in making a variety of products including insecticides, pharmaceuticals, cleaning products, textiles, and plastics.

You have probably heard people mention that chlorine is used in pools. Chlorine is used in pools to keep it clean and safe by killing bacteria, germs, and algae. It is also used in drinking water to kill bacteria so we don't get sick when we drink it. Because it kills germs, chlorine is also used in disinfectants and is the basis for most bleaches.

Chlorine is needed for the survival of animal life in the form of table salt (NaCl). Our body's use it to help us digest food, move our muscles, and fight off germs.

How was it discovered?

Chlorine gas was first produced by Swedish chemist Carl Wilhelm Scheele in 1774. However, for many years scientists thought that the gas contained oxygen. It was English chemist Sir Humphry Davy who proved that it was a unique element in 1810. He also gave the element its name.

Where did chlorine get its name?

Chlorine gets its name from the Greek word "chloros", which means "yellow-green."

Isotopes

Chlorine has two stable isotopes: Cl-35 and Cl-37. Chlorine found in nature is a mixture of these two isotopes.

Interesting Facts about Chlorine

• Chlorine gas was used by the Germans in WWI to poison the Allied soldiers.
• Around 1.9% of the ocean's mass is composed of chlorine atoms.
• It has a high density for a gas of 3.21 grams per liter (air is around 1.29 grams per liter).
• Chlorine is used to make chlorofluorocarbons or CFCs. CFCs were once widely used in air conditioners and spray cans. Unfortunately, they contributed to destroying the ozone layer and have been mostly banned.
• Most chlorine gas for industry is produced by using electrolysis on water that contains dissolved sodium chloride (salt water).

Iodine

 Iodine

<---Tellurium       Xenon--->

Symbol: I Atomic Number: 53 Atomic Weight: 126.904 Classification: Halogen Phase at Room Temperature: Solid Density: 4.933 grams per cm cubed Melting Point: 113.7°C, 236.66°F Boiling Point: 184.3°C, 363.7°F Discovered by: Bernard Courtois in 1811

Iodine is the fourth element in the seventeenth column of the periodic table. It is classified as a halogen and a non-metal. Iodine atoms have 53 electrons and 53 protons with 7 valence electrons in the outer shell.

Characteristics and Properties

Under standard conditions iodine is a dark blue-black solid. Iodine crystals can sublimate directly from a solid to a gas. As a gas, iodine is a purple vapor.

Iodine is a fairly active element, but is somewhat less active than the other halogens above it in the periodic table which include bromine, chlorine, and fluorine. Iodine can form compounds with many elements. Some of its most common compounds are formed with sodium and potassium.

Pure iodine can be dangerous to handle causing the skin to burn and damage to the eyes.

Where is it found on Earth?

Iodine is fairly rare, but is found in both the Earth's crust and in ocean water. There is actually a higher concentration of iodine in the ocean than in the Earth's crust. Some ocean plants such as seaweed have a high concentration of iodine. It is also found in underground brines near oil and natural gas reserves.

How is iodine used today?

Iodine has a number of uses. It is used in sanitation systems and as an antiseptic to kill germs and bacteria. It is also used in its radioactive form to enable doctors to diagnose medical issues and diseases.

Other applications include animal feed, cloud seeding, dyes, and photography.

Iodine is also an essential element for life. It plays an important role in the thyroid gland that controls the body's growth rate. Too little iodine can cause a person to have stunted growth and slower cognitive development (less intelligent). To make sure that people get enough iodine, it is often added to salt in what is called iodized salt.

How was it discovered?

Iodine was first discovered and isolated by French chemist Bernard Courtois in 1811. Courtois stumbled across iodine when running experiments on seaweed. It was French chemist Gay-Lussac who first named iodine as a new element and suggested the name.

Where did iodine get its name?

Iodine gets its name from the Greek word "iodes" which means "violet."

Isotopes

Iodine has one stable isotope that occurs naturally, iodine-127.

Interesting Facts about Iodine

• Many people get the iodine they need in their diets from eating seaweed.
• It is the heaviest element that is essential for human life and health.
• Foods rich in iodine include fish, diary products (milk, cheese, yogurt), some fruits and vegetables, and iodized salt.
• Pregnant women need more iodine than the average person. They can get this through dietary supplements.
• Too much iodine is harmful and can make a person very sick. Never take iodine unless instructed by a doctor.

Is the Ozone Layer Finally Healing Itself?

 

Is the Ozone Layer Finally Healing Itself?

Earth is currently experiencing a host of environmental problems. Air and water pollution continue to plague much of the world; exotic plants, animals, and other organisms pop up in parts of the globe that have no natural defense against them; and, all the while, climate change lingers in the headlines. It’s often difficult to find good environmental news, but environmentalists and scientists have reported one bright spot: the countries of the world rallying to combat the problem of ozone depletion.

Earth’s protective ozone layer sits some 15 to 35 km [9 to 22 miles] above Earth’s surface, in the stratosphere. Stratospheric ozone loss is worrisome because the ozone layer effectively blocks certain types of ultraviolet (UV) radiation and other forms of radiation that could injure or kill most living things. For 30 years countries around the world had worked together to reduce and eliminate the use of chlorofluorocarbons (CFCs) and other ozone-destroying chemicals (ODCs). However, scientists still could not say whether these efforts were helping. Was the ozone layer actually healing itself?

Before getting to the answer, it helps to have some background on the problem. In 1974 American chemists Mario Molina and F. Sherwood Rowland and Dutch chemist Paul Crutzen discovered that human-produced CFCs could be a major source of chlorine in the stratosphere. They also noted that chlorine could destroy extensive amounts of ozone after it was liberated from CFCs by UV radiation. Since then, scientists have tracked how the ozone layer has responded to CFCs, which, since their creation in 1928 had been used as refrigerants, cleaners, and propellants in hairsprays, spray paint, and aerosol containers. In 1985 a paper by the British Antarctic Survey revealed that stratospheric ozone concentrations over Antarctica had been dropping precipitously (by more than 60% compared with global averages) since the late 1970s. Throughout the 1980s and early 1990s, observations and measurements from satellites and other instruments showed that this “hole” over Antarctica was growing larger year after year, that a similar hole had opened over the Arctic, and that stratospheric ozone coverage worldwide had dropped 5% between 1970 and the mid-1990s, with little change afterward.

In response to the growing problem, much of the world came together in 1987 to sign the Montreal Protocol on Substances That Deplete the Ozone Layer, an agreement that allowed the world to begin to phase out the manufacturing and use of CFCs—molecules containing only carbon, fluorine, and chlorine atoms—and other ODCs. Follow-up meetings throughout the 1990s and early 2000s produced amendments aimed at limiting, reducing, and eliminating hydrobromofluorocarbons (HBFCs), methyl bromide, carbon tetrachloride, trichloroethane, hydrofluorocarbons (HFCs), hydrochlorofluorocarbons (HCFCs), and other ODCs. Even though nearly all of the planet’s governments had been working diligently toward a common goal—good news in itself—it was unclear whether these unprecedented efforts were having much of an effect.

In 2014, however, scientists received the first bit of good news on this topic: the first small increases in stratospheric ozone in more than 20 years had been detected, along with evidence that ODCs had declined by 10–15% in the atmosphere. Yet they remained cautious. Some two years later, scientists got sufficient data to confidently reveal proof that the ozone layer was indeed on a path to recovery. The 2016 study, which tracked the evolution of the size of the ozone hole over Antarctica, observed that stratospheric ozone concentrations were continuing to increase and that the size of the Antarctic ozone hole had declined by half the size of the continental U.S. between 2000 and 2015. They expected the ozone layer to fully heal sometime between 2040 and 2070.

In 2023, a United Nations study brought these estimates into further focus. It found that if countries continued to adhere to the limits imposed by the Montreal Protocol and its follow-on agreements, the world could expect that ozone concentrations would largely return to their pre-1980 levels by 2040, with the Arctic reaching pre-1980 levels by 2045 and the Antarctic following suit by 2066.

Carbon footprint

 Carbon footprint

The carbon footprint shows how much carbon dioxide and other greenhouse gases a person produces in everyday life.  It measures the amount of fossil fuels and electricity someone uses up as well as the carbon footprint of the products they buy.

When we use our cars or heat our homes with oil or natural gas, carbon dioxide and various other gases are set free.  These emissions lead to a denser atmosphere and global warming.

You can measure your carbon footprint by using a calculator that you can find on various websites. It shows you in which way your living habits damage the environment. The carbon footprint usually measured in tons of CO2 per year. In America for example, every citizen produces about 28 tons of carbon dioxide and other dangerous gases a year, in Great Britain the amount is about 10 tons.

 How to reduce your carbon footprint

There are many actions you can take to reduce your carbon footprint.

The way we travel, for example, has a major impact on our environment. Use your bike or walk for short distances. Public transport is a way of getting to places without putting a burden on the environment. If you use your car see to it that it is maintained correctly and that it does not burn more fuel than it should.

Buying local food is also a way of curbing emissions into the atmosphere. Many environmental experts, however, argue that it often saves energy to buy food that is produced naturally in faraway places than consuming food grown locally in greenhouses.

In your home you can contribute to saving energy by turning off lights if you don’t need them or by avoiding the use of air conditioners, which contribute a lot to global warming and emit CFCs that destroy the ozone layer. Electrical appliances can save energy if you set them to standby mode.

Recycling plastic, glass and paper can also reduce your carbon footprint drastically.

It is also vital to persuade others to take the same steps that you do. Only if we concentrate on reducing carbon emissions together can we hope to make our environment better.

 

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Carbon Dioxide

 

Carbon Dioxide

Carbon dioxide is a compound in which two oxygen atoms are connected to a carbon atom. At normal temperatures it is a colourless gas that exists naturally in the Earth’s atmosphere. The air that we breathe has about 0.03% of carbon dioxide in it.

Carbon dioxide is an important part of the carbon cycle and essential for life on Earth.  Without it temperatures on our planet would be very low.

Plants use the sunlight and take up the CO2 in the atmosphere to produce energy and oxygen. This process is called photosynthesis.

The gas is also produced when fossil fuels are burned. Carbon dioxide that has been stored for millions of years in coal, oil and natural gas is set free. Living creatures produce carbon dioxide when they breathe out. It is emitted from volcanoes and hot springs. Deforestation sets carbon that is stored in trees free.

Carbon dioxide is an important greenhouse gas. Light that enters the atmosphere it is converted to heat. Higher amounts of CO2 make the atmosphere denser and keep it from getting out. CO2 is a gas that is highly responsible for global warming. Since the Industrial Revolution of the 1800s the amount of CO2 in our atmosphere has risen by 40%.

Throughout the centuries carbon dioxide has been in balance. Now more carbon dioxide is being produced than can be absorbed by nature.

Uses of Carbon Dioxide

Carbon dioxide is used in various industries to produce food, chemicals and oil products. It is especially common as a food additive and is added to beverages to give fizz to sparkling wine and water. It is also responsible for a beer’s foam.

As a pressurized gas carbon dioxide is used in fire extinguishers because it does not burn. Put in cartridges it can be used to inflate bike tires. In its solid form CO2 is called dry ice. It is used for cooling fresh food or ice cream. Liquid carbon dioxide is needed to remove caffeine from coffee

Carbon dioxide in oceans

Oceans are carbon sinks. They absorb more than 25% of all the carbon dioxide that people emit into the atmosphere. As a result, the ocean’s water is becoming more acidic. This change affects the food chain and all sea organisms.

Carbon dioxide poisoning

Although carbon dioxide is not poisonous in normal amounts it can kill you if there is more than 10% in the air. High concentrations can lead to dizziness, bad sight, breathing problems as well as a high blood pressure and an increased heart beat. High levels of CO2 occur when there is not enough fresh air in a room.