chemicals

UNEP Chemicals Branch
The Chemicals Branch works towards making the world a safer place from toxic chemicals by helping governments take needed global actions for the sound management of chemicals, by promoting the exchange of information on chemicals, and by helping to build the capacities of countries around the world to use chemicals safely.

Persistent Organic Pollutants (POPS)
POPs are chemicals that persist, bioaccumulate in plants and animals, are transported long distances in the environment, and are toxic to people. The UNEP Chemicals Branch work on POPs facilitates the negotiations of a legally binding international instrument on POPs and promotes the early reduction and elimination of releases of POPs into the environment through information exchange and capacity building programmes.

OzonAction Branch
Under the Montreal Protocol on Substances that Deplete the Ozone Layer, countries worldwide are taking specific, time-targeted actions to reduce and eliminate the production and consumption of man-made chemicals that destroy the stratospheric ozone layer, Earth’s protective shield.

GEF Reduction of Persistent Organic Pollutants
In May 2001, governments adopted the Stockholm Convention on Persistent Organic Pollutants (POPs) and named the GEF as the Convention's interim financial mechanism, pending entry into force of the Convention. In October 2002, the GEF Assembly approved the addition of POPs as a new focal area.

Global Mercury Assessment
This website supports the process to develop a global assessment of mercury and its compounds, including an outline of options for addressing any significant global adverse impacts of mercury.

Implementation of Strategic Approach to International Chemicals Management (SAICM)
The Governing Council of UNEP has requested the Executive Director, as a matter of high priority, to make appropriate provision for the implementation of UNEP’s responsibilities under SAICM and to make provision for activities to support developing countries and countries with economies in transition in implementing the strategic approach to international chemicals management, taking into account the Bali Strategic Plan for Technology Support and Capacity-building.

Lead and Cadmium Activities
UNEP is developing reviews of scientific information on lead and cadmium, focusing especially on long-range environmental transport, as requested by the UNEP Governing Council, in order to inform future discussions of the Governing Council on the possible need for global action in relation to these two heavy metals.

Partnership for Clean Fuels and Vehicles Clearing-house
UNEP is the clearing-house for the global Partnership for Clean Fuels and Vehicles, launched by World Summit partners in September 2002 at the World Summit on Sustainable Development.

Chemicals Information Exchange Network
The Chemical Information Exchange Network (CIEN) is a network of people involved in the management of chemicals.

Trade Names of Chemical Products Containing Ozone Depleting Substances and their Alternatives
The service Trade Names of Chemical Products containing ozone depleting substances and their alternatives is designed to help customs officials and National Ozone Units control imports and exports of ozone depleting substances (ODS) and prevent their illegal trade. It is a worldwide database of the commercial trade names of chemical products containing ODS controlled under the Montreal Protocol and their alternatives.

Global Programme of Action for the Protection of the Marine Environment from Land Based Activities (GPA)
The GPA aims at preventing the degradation of the marine environment from land-based activities by facilitating the duty of States to preserve and protect the marine environment.

Director

Is Group Director, Strategy and Business Development at the Dawood Group. He has had the experience of working in senior management positions in multinational and large Pakistani Organizations. He held the position of Finance Director, Supply Chain Director and Head of Business Unit at Reckitt Benckiser (previously Reckitt & Colman) and was the Managing Director Haleeb Foods (previously CDL Foods Limited). He has also been the Financial Advisor at Indus Motor Company Limited. He holds a Masters Degree in Economics and is a Chartered Accountant from the Institute of Chartered Accountants of England & Wales, he joined the ECPL Board in 2006.

Director

Is a Senior Vice President of Engro Chemical Pakistan Limited and Chief Executive of Engro Polymer & Chemicals Limited. He is Chairman and Chief Executive of Engro Polymer Trading (Pvt) Limited and a director of Engro Energy (Pvt) Limited. He has held key assignments at Engro and with Exxon Chemical Canada. A Chemical Engineer by qualification, he joined the ECPL Board in 1997.

Director

Is currently the Chairman and Chief Executive Officer of Oil & Gas Development Company Limited. He holds a Masters degree in Economics as well as Political Science. He joined ECPL Board in 2002.
Prior to his current assignment, he was the Country Chairman and Managing Director of Caltex Oil Pakistan Limited and has served as a Director on the Boards of Pakistan Refinery Limited and Pak Arab Pipeline Company Limited. He is also a former President of the American Business Council of Pakistan and has undertaken several key assignments with Caltex Oil both in-country and overseas. Arshad is also serving as a Director on the Boards of PIDC and Mari Gas Company Limited.

Chief Executive

Is President and Chief Executive of Engro Chemical Pakistan Limited and Chairman of Engro Polymer & Chemicals Limited, Engro Vopak Terminal Limited, Engro Foods Limited, Engro Energy (Pvt) Limited, Engro Innovative Automation (Pvt) Limited and Advanced Automation LP. He is also a member of the Board of Directors of Oil & Gas Development Company Limited, Pakistan Business Council and Member of the Board of Trustees of Lahore University of Management Sciences (LUMS). He has held key assignments at Engro and with Exxon Chemical in Canada. A Masters in Business Administration, he joined the ECPL Board in 2000.

Though the periodic table has only 118 or so elements, there are obviously more substances in nature than 118 pure elements. This is because atoms can react with one another to form new substances called compounds (see our Chemical Reactions module). Formed when two or more atoms chemically bond together, the resulting compound is unique both chemically and physically from its parent atoms.

Let's look at an example. The element sodium is a silver-colored metal that reacts so violently with water that flames are produced when sodium gets wet. The element chlorine is a greenish-colored gas that is so poisonous that it was used as a weapon in World War I. When chemically bonded together, these two dangerous substances form the compound sodium chloride, a compound so safe that we eat it every day - common table salt!

In 1916, the American chemist Gilbert Newton Lewis proposed that chemical bonds are formed between atoms because -19 coulombs and a mass of 9.11 × 10^-31 kg. Electrons are generally found around the nucleus of an atom, but may be gained or lost during ion formation. Compare to the proton.');">electrons from the atoms interact with each other. Lewis had observed that many elements are most stable when they contain eight electrons in their valence shell. He suggested that atoms with fewer than eight 2 2s² 2p⁶ 3s¹; the 3s electron is the only valence electron in the atom. Valence electrons determine the chemical properties of an atom and are the only electrons that participate in chemical bonding.');">valence electrons bond together to share electrons and complete their 2O, oxygen has a valence of two; in CH₄, carbon has a valence of four.');">valence shells.

While some of Lewis' predictions have since been proven incorrect (he suggested that -19 coulombs and a mass of 9.11 × 10^-31 kg. Electrons are generally found around the nucleus of an atom, but may be gained or lost during ion formation. Compare to the proton.');">electrons occupy cube-shaped orbitals), his work established the basis of what is known today about chemical bonding. We now know that there are two main types of chemical bonding; ionic bonding and covalent bonding.

Ionic Bonding
In ionic bonding, -19 coulombs and a mass of 9.11 × 10^-31 kg. Electrons are generally found around the nucleus of an atom, but may be gained or lost during ion formation. Compare to the proton.');">electrons are completely transferred from one atom to another. In the process of either losing or gaining negatively charged electrons, the reacting atoms form ions. The oppositely charged ions are attracted to each other by electrostatic forces, which are the basis of the ionic bond.

For example, during the reaction of sodium with chlorine:

Notice that when sodium loses its one 2O, oxygen has a valence of two; in CH₄, carbon has a valence of four.');">valence -19 coulombs and a mass of 9.11 × 10^-31 kg. Electrons are generally found around the nucleus of an atom, but may be gained or lost during ion formation. Compare to the proton.');">electron it gets smaller in size, while chlorine grows larger when it gains an additional 2 2s² 2p⁶ 3s¹; the 3s electron is the only valence electron in the atom. Valence electrons determine the chemical properties of an atom and are the only electrons that participate in chemical bonding.');">valence electron. This is typical of the relative sizes of ions to atoms. Positive ions tend to be smaller than their parent atoms while negative ions tend to be larger than their parent. After the reaction takes place, the charged Na⁺ and Cl^- ions are held together by electrostatic forces, thus forming an ionic bond. Ionic compounds share many features in common:

• Ionic bonds form between metals and nonmetals.
• In naming simple ionic compounds, the metal is always first, the nonmetal second (e.g., sodium chloride).
• Ionic compounds dissolve easily in water and other polar solvents.
• In solution, ionic compounds easily conduct electricity.
• Ionic compounds tend to form crystalline solids with high melting temperatures.

This last feature, the fact that ionic compounds are solids, results from the intermolecular forces (forces between molecules) in ionic solids. If we consider a solid crystal of sodium chloride, the solid is made up of many positively charged sodium ions (pictured below as small gray spheres) and an equal number of negatively charged chlorine ions (green spheres). Due to the interaction of the charged ions, the sodium and chlorine ions are arranged in an alternating fashion as demonstrated in the schematic. Each sodium ion is attracted equally to all of its neighboring chlorine ions, and likewise for the chlorine to sodium attraction. The concept of a single molecule becomes blurred in ionic crystals because the solid exists as one continuous system. Forces between molecules are comparable to the forces within the molecule, and ionic compounds tend to form crystal solids with high melting points as a result.

Covalent Bonding
The second major type of atomic bonding occurs when atoms share -19 coulombs and a mass of 9.11 × 10^-31 kg. Electrons are generally found around the nucleus of an atom, but may be gained or lost during ion formation. Compare to the proton.');">electrons. As opposed to ionic bonding in which a complete transfer of electrons occurs, covalent bonding occurs when two (or more) elements share electrons. Covalent bonding occurs because the atoms in the compound have a similar tendency for electrons (generally to gain electrons). This most commonly occurs when two nonmetals bond together. Because both of the nonmetals will want to gain electrons, the elements involved will share electrons in an effort to fill their valence shells. A good example of a covalent bond is that which occurs between two hydrogen atoms. Atoms of hydrogen (H) have one 2 2s² 2p⁶ 3s¹; the 3s electron is the only valence electron in the atom. Valence electrons determine the chemical properties of an atom and are the only electrons that participate in chemical bonding.');">valence electron in their first electron shell. Since the capacity of this shell is two electrons, each hydrogen atom will "want" to pick up a second electron. In an effort to pick up a second electron, hydrogen atoms will react with nearby hydrogen (H) atoms to form the compound H₂. Because the hydrogen compound is a combination of equally matched atoms, the atoms will share each other's single electron, forming one covalent bond. In this way, both atoms share the stability of a full 2O, oxygen has a valence of two; in CH₄, carbon has a valence of four.');">valence shell.

1. In order to fully understand the mechanisms of human physiology it is important to have an understanding of the chemical composition of the body. This will come in handy when considering the various interactions between cells and structures. We will gloss over the basic chemistry; however, if there are specific questions with regards to chemistry and its effect on biological function feel free to ask on the forum.