What can the Periodic Table tell us about everyday chemicals

The periodic table and its structure
  

              

Periods - the rows of the periodic table are arranged in what we call periods. The periodic table has seven periods in total. Period 1 contains only two elements: hydrogen and helium. Period 6 (including the lanthanides) contains 32 elements and so it contains more elements than any other period. The period can tell us how many shells a element has, so elements in period 1 will have one shell.

Each period begins with an alkali metal and ends with a noble gas, though period 7 is not complete; it is predicted that there is a noble gas with a atomic number of 118 (its current chemical formula is Uuo) but this element’s existence has not been proven yet.

As you go across a period, the number of electrons in the outer shells starts to increase. For example, in period 2, Li (lithium) has one electron in its the outer shell, B (boron) has 3 electrons in the outer shell and Ne (neon) has 8 electrons in the outer shell.  

Groups - this is the name given to the vertical columns of the periodic table. Elements in a group share many common properties. All the elements in a certain group have the same number of electrons in the outer shells. The outer electrons are called valence electrons. Because they have the same number of valence electrons (number of electrons in the outer shell), elements in a group share similar chemical properties. The Roman numerals listed above each group are the usual number of valence electrons.

Details on specific elements   

Chlorine

The periodic table tells us that chlorine(Cl) can be found in 3rd period and the 7th group. The element is situated at the far right side of the table (so it is a nonmetal). It has a relative atomic mass of 35.45 AMU (atomic mass unit). Chlorine is a halogen (because it is in the 7th group) and has two stable isotopes (explained later). Chlorine is gas at room temperature.  Its electronic structure is 2.8.7. Its atomic number is 17.

Appearance and properties - Chlorine is greenish-yellow, irritating and toxic gas with a choking smell. Its properties are:

• It has a melting point of -100.98°C
• Its boiling point is -34.6°C
• Chlorine is in many reactions, particularly in substitutions with hydrogen.
• The gas irritates respiratory and other mucous membranes.\
• Chlorine in liquid form is corrosive and so will burn the skin.
• Humans can smell as low an amount as 3.5 ppm(parts per million). As chlorine is toxic, few breaths at a concentration of 1000 ppm is usually fatal.
• As a gas, chlorine is a diatomic molecule (Cl2) which means that there is two chlorines in each molecule of chlorine.

This is the electron shell configuration of Chlorine.

Uses - Chlorine is widely used in many different areas. It was used as a weapon during the First World War (to poison the enemy by having gas attacks). The gas is made on a large scale from the electrolysis of table salt (sodium chloride)/sylvite (KCl) or the evaporation of water from salt water. Furthermore, it is used to manufacture consumer products such as paper, dyestuffs, textiles, petroleum products, medicines, antiseptics, insecticides, foodstuffs, solvents, paints and plastics. It is also used to make important chemicals such as chlorates, chloroform, carbon tetrachloride and bromine. A extra use for this element is in organic chemistry, both as an oxidising agent and in substitution reactions. It is also used to purify drinking water and to disinfect swimming pools and drinking water. Our daily intake is about 6g, mainly in the form of salt.

Reaction and uses of its compounds:

Chlorine is used to make Table salt (NaCl). The reaction to make table salt is as follows:

2Na + Cl2 → 2NaCl

  

Also, Chlorine is used to make a chemical compound called chloroform  - a strong liquid (CHCl3) which, when vapors are inhaled, causes strong anesthetic effects. Chloroform is thought to be carcinogenic, toxic to the heart and liver. Abuse can cause sudden death.

To make chloroform, bleach is mixed with acetone/alcohol. The reaction is:

NaClO  + C3H6O →  CHCl3 + 2 NaOH + CH3COONa  

Health and safety:

As chlorine is toxic, few breaths at a concentration of 1000 ppm is usually fatal. So it is important that any reaction done using chlorine is done in a fume cupboard. Also bleach (a product of chlorine) vapours are toxic so nasal masks should be used when working with bleach. Chlorine can burn skin and so gloves should be used when working with products with high concentrations of chlorine.

Isotopes:

In total, the total number of chlorine isotopes are 16, with atomic mass ranging from 31 - 46. Out of all the isotopes, chlorine has two stable isotopes: Cl-35 and Cl-37 with Cl-35 as the most abundant form (75.8%). That is why the relative atomic mass of Chlorine is 35.453 AMU.

Stable isotopes are those that do not have an half life/ decay i.e. they do not split into 2 periodically. The amount of these isotopes in the earth remains the same.

Unstable isotopes are the isotopes are the opposite. They have half life; they decay so they half every few years.

Extra information:

• Chlorine leaks in containers are detected using ammonia. Ammonia will react with the chlorine and form a white mist above the leak.
• The most common natural chlorine compound on Earth is sodium chloride or table salt.
• Chlorine is the 21st most abundant element in the Earth's crust

Copper

The periodic table tells us that copper(Cu) can be found in 4th period and the 11th group (not shown in periodic table in first page). The element is situated at the centre side of the table (so it is a metal). It has a relative atomic mass of 63.546 AMU (atomic mass unit). Its atomic number is 29. Copper is a transition metal (because it is in the 11th group). Copper is solid at room temperature.  Its electronic structure is 2.8.18.1.

Appearance and properties

Copper is a very shiny metal. It has an orange-gold colour. It is a really good conductor of electricity, second only to silver. it doesn't corrode easily and is relatively cheap since its very abundant in the earth’s crust. Also, copper is very malleable (can be hammered into shape) and is very ductile (can be drawn into wires) and so it is used in water tubes and electrical conductors.

More properties:

• Melting point - 1083.040K.
• Boiling point - 25670K

Uses:

One of the main of uses of copper is its use in the electrical industry. Copper is used to make components, wires… Copper is used in plumbing; it is used to make water tubes. Copper is used to make cookware e.g. bottom of frying pans because it is a good conductor of heat. Copper is used in pesticides (chemicals that kills insects or other organisms harmful to cultivated plants or to animals.) Many coins contain copper.

Isotopes:

There are 28 known isotopes of copper with atomic mass ranging from 53 to 80 AMU. There are two stable isotopes: Cu-63 (69.15% abundance) and Cu-65 (30.85% abundance).

Health and safety:

Copper is non-toxic. So coming with contact with copper is dangerous. We intake copper into our body through food and water. Copper is good for our health, so sufficient amounts of copper is needed to be consumed each day. Exposure to copper often occurs. In the working environment, copper contagion can lead to a flu-like condition that is known as metal fever. This condition passes in about two days and is caused by over sensitivity.

Reactions of copper and its compounds:

4Cu + O2 → 2Cu2O

Cu + F2 → CuF2

Cu + Cl2 → CuCl2

Cu + Br2 → CuBr2

Other very interesting facts about copper:

• The history of the use of copper extends to the ancient times. Historians even call the period of time between the Neolithic and Bronze Ages the Copper Age.
• Some interesting chemistry:
• Copper(I) burns blue in a flame test.
• Copper(II) burns green in a flame test.
• Copper's atomic symbol Cu is derived from the Latin term 'cuprum' meaning 'metal of Cyprus'.
• An interesting use of copper sulfate compounds is that such compounds are used to prevent fungus and algae growth in standing water supplies such as ponds and fountains.
• Copper is a red-orange metal that darkens to a brown color as it is exposed to air. If it is exposed to air and water, it will form a verdigris of blue-green.
• Copper sheets were added to the bottom of ships to prevent 'biofouling' where seaweed, and barnacles would cling to ships and slow the ships down. Today, copper is mixed into the paint that is used to paint the underside of ships.

Carbon

The periodic table tells us that carbon(C) can be found in 3th period and the 4th group. The element is situated at the right side of the table (so it is a non-metal). It has a relative atomic mass of  12.011 AMU (atomic mass unit). Its atomic number (as shown in the periodic table) is 16. Carbon is solid at room temperature.  Its electronic structure is 2.4.

Appearance and properties

Carbon can be found in three different forms; amorphous (lampblack, bone black), graphite, and diamond. This forms are called the allotropic forms of carbon. But, normally, carbon is found as amorphous (lampblack, bone black)).  

Uses:

Carbon is used to make numerous and varied amounts of compounds with limitless applications. Many thousands of carbon compounds are integral to life processes (carbon is one of the most abundant elements in our body).

Diamond is bought as a gemstone (because of its attractiveness) and is used for cutting and drilling(as it is one of the most hardest substances in the earth and diamond can be made very sharp).

Carbon as graphite is used for melting metals, in pencils, for rust protection; for lubrication; and as a moderator for slowing neutrons for atomic fission. Amorphous carbon is used for removing tastes and odors. Carbon as coal is also used as a fuel supply (in power stations, coal-fired trains etc).. Melting point of carbon is 3820 0K and its boiling point is 5100 0K.

Reactions of carbon and its compounds:

C + O2 → CO2

C6H12O6 + O2 → CO2 + H2O  (aerobic respiration reaction)

CO2 + 12 H2O → C6H12O6 + 6 O2 + 6 H2O   (photosynthesise reaction)

Oxygen

The periodic table tells us that oxygen(O) can be found in 3th period and the 6th group (not shown in periodic table in first page). The element is situated at the centre side of the table (so it is a metal). It has a relative atomic mass of 63.546 AMU (atomic mass unit). Its atomic number is 29. Oxygen is a gas at room temperature.  Its electronic structure is 2.6.  

Appearance and properties:

Oxygen gas is colorless, odorless, and tasteless. The liquid and solid forms are a pale blue color and are strongly paramagnetic (polar). Oxygen lets combustion takes place, combines with most elements (i.e. oxidises most elements), and is a component of hundreds of thousands of organic compounds. Ozone, a compound of oxygen, protects humans by acting as a UV light barrier.

Uses:

Until 1961, oxygen was used as the atomic weight standard (1/16th of a mole of oxygen was 1 AMU. Mole is a unit that is used to quantify the mass of elements) but  International Union of Pure and Applied Chemistry adopted carbon 12 as the new basis. As oxygen is the third most third most abundant element found in the sun and the earth, it plays a part in the carbon-nitrogen cycle. Oxygen enrichment of steel blast furnaces accounts for the greatest use of the gas.

Large quantities of oxygen are used in making synthesis gas for ammonia, methanol, and ethylene oxide. It is also used as a bleach, for oxidizing oils, for oxy-acetylene welding, and for determining carbon content of steel and organic compounds. Plants and animals require oxygen for respiration. Hospitals frequently prescribe oxygen for patients. Approximately two thirds of the human body and nine tenths of the mass of water is oxygen.     

• Density (g/cc): -183°C)
• Melting Point: 54.8 0K
• Boiling Point: 90.19 0K

Argon

Argon is inert (inactive) and so hence its name (argon if inactive in greek).  Argon has a freezing point of -189.2°C, boiling point of -185.7°C, and density of 1.7837 g/l. Even though argon is a noble gas, it does form a hydrate with a dissociation pressure of 105 atm at 0°C. Argon is two and a half times more soluble in water than nitrogen, with approximately the same solubility as oxygen. It is a gas in room temperature.  It is a non-metal.

Uses:

Argon is used in electric lights and in fluorescent tubes, photo tubes, glow tubes, and in lasers. Argon is used as an inert gas for welding and cutting, blanketing reactive elements, and as a protective (non-reactive) atmosphere for growing crystals of silicon and germanium.

Health and safety:

Argon is an inert gas. It is non-toxic and can only present a problem if it displaces air (or the oxygen in air). This may lead to suffocation. As long as there is "enough" oxygen in the air for breathing, argon will not be harmful.