Chemical Bonds assignment (Clement Chia (09)(2a2))

Carbon Monoxide

The harmful compound I chose to talk about is carbon monoxide (CO). Carbon monoxide is made up of two atoms, an oxygen atom and a carbon atom.

Medical Consequences

Carbon monoxide mainly causes adverse effects in humans by combining with hemoglobin to form carboxyhemoglobin (HbCO) in the blood. This prevents oxygen binding to hemoglobin, reducing the oxygen-carrying capacity of the blood, leading to hypoxia. Carboxyhemoglobin can revert to hemoglobin, but the recovery takes time because the HbCO complex is fairly stable. Cerebral edema (swelling of the brain) is also a common result of severe carbon monoxide poisoning that entails the destruction of brain cells by compressing them into themselves within the cranial compartment causing delayed neurological problems that involve the "higher" or cognitive functions.

Oxygen

Oxygen (O) is a colourless and odourless gas. There is 21% of oxygen in the air. It is a harmless element that has many uses. For example, it is required for breathing for aerobic respiration (the production of energy from glucose) and also to sustain combustion.

Carbon

Carbon (C) can be found in coal deposits underground, in organic compounds like dead matter (biomass) and in the air in substances like carbon dioxide (CO²). Carbon is used in the carbon cycle, which is essential for life also.

Chemical Bonding

Type of Chemical Bond : Covalent Bonding

Dot and cross Diagram

References:

http://www.carbonmonoxidekills.com/32/facts

http://library.thinkquest.org/11226/why.htm http://en.wikipedia.org/wiki/Carbon

http://en.wikipedia.org/wiki/Carbon

Science chemical bonds online assignment (Aceson Aw 1, 2a2)

Science online learning
A harmful compound that is formed when two or more harmless elements react together
Compound: Nitric acid
Formula: HNO3
Elements: Hydrogen, Nitrogen, Oxygen
Bond: Covalent
Write up: Nitric acid is a compound formed chemically, which is made up of the elements, oxygen, hydrogen, and nitrogen. Nitric Acid is highly toxic, highly toxic, and reacts with most metals. Pure anhydrous nitric acid (100%) is a colourless mobile liquid with a density of 1.522 g/cm3 which solidifies at −42 °C to form white crystals and boils at 83 °C. When boiling in light, and slowly even at room temperature, there is a partial decomposition. It reacts with most metals except for some, like gold, and also many organic materials, it can be explosive. Nitric acid is also commonly used as strong oxidizing agent.
Nitrogen: odorless, tasteless and colourless. Nitrogen can be used as a fertilizer. Nitrogen has the chemical symbol N and atomic number 7 in the periodic table. It forms 78.08% by volume of Earth's atmosphere. Nitrogen has extremely strong chemical bonds, but when the bonds are broken from compounds, due to burning, decay, nitrogen gas is released into the atmosphere. A nitrogen atom has five valence electrons.
Oxygen: odorless, tasteless and colourless. Oxygen is needed for respiration and burning. It has the chemical symbol O and atomic number 8. Oxygen makes up 20.8% of the world’s atmosphere. Another form (allotrope) of oxygen, ozone (O3), helps protect the biosphere from ultraviolet radiation with the high-altitude ozone layer
Hydrogen: The lightest and most abundant element, it is highly flammable. It constituting roughly 75 % of the Universe's chemical elemental mass. Hydrogen forms compounds with most elements and is present in water and most organic compounds. It plays a particularly important role in acid-base chemistry with many reactions exchanging protons between soluble molecules. It is the simplest of elements and produces water when hydrogen gas is burned. Hydrogen is colorless, odorless, non-metallic, and tasteless.

Dot and Cross diagram








Sources: http://en.wikipedia.org/wiki/Hydrogen
http://en.wikipedia.org/wiki/Oxygen
http://en.wikipedia.org/wiki/Nitrogen
http://en.wikipedia.org/wiki/Nitric_acid

Valentine's Day Online Assignment Submission by Zhang Jie

Dots and Cross Diagram:


Carbon Dioxide (CO2) is a harmful substance (fatal if excessed amount is taken in) formed by bonding 2 oxygen atoms and 1 carbon atom. The type of bonding involved is Covalent Bonding, which occurs by sharing of electrons between atoms of non-metallic elements so as to achieve the stable electronic configuration of a noble gas. In this case, O=H=O, and thus each of the atoms has 8 electrons.

Oxygen (harmless): A colorless gas that has no smell or taste under room temperature and standard pressure or a pale blue liquid at −182.95 °C. It makes up 20.8% of the Earth’s atmosphere and it is essential for living. All living things take in oxygen for respiration to stay alive. Oxygen is also found in water, which is another essential factor of all living things. An oxygen molecule consists of 2 oxygen atoms.

Carbon (harmless): A solid that is either clear (diamond) or black (graphite) under room temperature and standard pressure that has no smell or taste. It is essential for living because it makes up 18.5% of human body (second most abundant after oxygen).
Carbon Dioxide (harmful): is a gas at standard temperature and pressure and exists in Earth's atmosphere in this state. CO2 is a trace gas comprising 0.039% of the atmosphere.

Effects of Carbon Dioxide: The primary health dangers of carbon dioxide are:
- Asphyxiation. Caused by the release of carbon dioxide in a confined or unventilated area. This can lower the concentration of oxygen to a level that is immediately dangerous for human health.
- Frostbite. Solid carbon dioxide is always below -78 oC at regular atmospheric pressure, regardless of the air temperature. Handling this material for more than a second or two without proper protection can cause serious blisters, and other unwanted effects. Carbon dioxide gas released from a steel cylinder, such as a fire extinguisher, causes similar effects.
- Kidney damage or coma. This is caused by a disturbance in chemical equilibrium of the carbonate buffer. When carbon dioxide concentrations increase or decrease, causing the equilibrium to be disturbed, a life threatening situation may occur.

References:
http://en.wikipedia.org/wiki/Oxygen
http://en.wikipedia.org/wiki/Carbon_dioxide#Chemical_and_physical_properties
http://www.ehs.ufl.edu/Lab/Cryogens/oxygen.html
http://en.wikipedia.org/wiki/Carbon
http://www.lenntech.com/carbon-dioxide.htm

Osium tetroxide

Osmium tetroxide exists as a pale yellow-brown crystalline solid with a characteristic acrid chlorine-like odor. In fact, theelement name osmium is derived from osme, Greek forodor. OsO₄ is volatile: it sublimes at room temperature. It is soluble in a wide range of organic solvents, and moderately soluble in water, with which it reacts reversibly to form osmic acid (see below). Pureosmium tetraoxide is probably colourless and it has been suggested that its yellow hue is due to osmium dioxide (OsO₂) impurities although osmium (IV) oxide normally exists as a black powder so this may not be true. Osmium tetroxide molecule is tetrahedral and therefore non-polar. This nonpolarity helps OsO₄ penetrate charged cell membranes. OsO₄ is 518 times more soluble in CCl₄ than in water.

With a d⁰ configuration, Os(VIII) is expected to form tetrahedral complexes when bound to four ligands. Tetrahedral structures are seen for the electronically related oxides MnO₄⁻ and CrO₄²⁻.

The osmium of OsO₄ has a formal oxidation state of +8, the highest oxidation state known for a transition metal. The osmium atom has eight valenceelectrons. If one assumes that two electrons are donated by each of the four oxide ligands, the total electron count for the complex is 16, as also seen for the isoelectronic speciespermanganate and chromate.

The high oxidation state of osmium in this compound can be rationalized by comparison of main-group and transition-metal chemistry. Just as the elements in groups 3 through 7 form compounds analogous to those formed by elements in groups 13 through 17 (e.g. TiCl₄ and GeCl₄, VF₅ and AsF₅, CrO₄²⁻ and SeO₄²⁻, etc.), we might expect the elements in group 8 to form compounds analogous to those formed by the noble gases. This is in fact the case, as demonstrated by the existence of compounds like OsO₄ and XeO₄.

OsO₄ is formed slowly when osmium powder reacts with O₂ at 298 K. Reaction of bulk solid requires heating to 670 K.

Os + 2 O₂ → OsO₄

_{References:http://en.wikipedia.org/wiki/Osmium_tetroxide}

online lesson, chemical bonding by anthony low(25)

Harmless element: nitrogen
Harmless element: oxygen
Oxygen (O) + nitrogen (N) = nitrous oxide. (N2O). Covalent bonding is taking place when the 2 elements bond together. It is because it is between two non-metallic elements.
Introduction to the elements
Nitrogen: elemental nitrogen is a harmless gas that is colorless, odorless and tasteless. It consist 78.08% by volume of Earth's atmosphere. Nitrogen is needed in plants to make protein from pure carbohydrate. If plants don’t have nitrogen, they can’t survive and when plants can’t survive, human will not exist anymore.
Source: http://en.wikipedia.org/wiki/Nitrogen
http://wiki.answers.com/Q/How_do_plants_use_nitrogen
Oxygen: oxygen gas consists about 20% of Earth’s atmosphere. It is one that human cannot live without. We need it for respiration round the clock. The ozone layer is made up of oxygen which protects the earth from the ultraviolet radiations of the sun. Without the ozone layer, Earth would become very hot. So oxygen is also definitely not a harmful element and it is very useful for human etc…
Source: http://en.wikipedia.org/wiki/Oxygen
http://www.blurtit.com/q304435.html
Nitrous Oxide
However, Sustain level of nitrous oxide can be very harmful to your body like tissue damages etc... Also, when nitrous oxide react with the rain when lightning strikes, it forms acid rain. Acid rain will destroy lots of buildings and structures and it is also not good for humans as it will also destroy crops. It is ranked third behind carbon dioxide and methane in contributing to global warming.
Source: http://www.triplepundit.com/2010/04/nitrous-oxides- global-warming-impact-no-laughing-matter
http://en.wikipedia.org/wiki/Nitric_oxide
Formation of nitrous oxide
It can be made my 2 ways:
• Human-made:
Agricultural soils are by far the biggest source. Some of the nitrogen can end up being emitted as N2O through the processes of nitrification and denitrification. Globally, between 2 and 4 million tonnes of N2O-N are thought to be released into the atmosphere each year via this pathway.
• Natural:
Temperate and tropical soils, with the world's oceans also being an important contributor. Total annual emissions of N2O from natural sources are estimated to be about 10 million tonnes.
Sources: http://www.eoearth.org/article/Nitrous_oxide
http://www.triplepundit.com/2010/04/nitrous-oxides-global-warming-impact-no-laughing-matter

Online lesson chemical bonding done by Javier Toh

My Dot and Cross diagram >>

The harmul compound which i have found is Sulfur dioxide.
Sulfur dioxide is a harmul compound made up of sulfur and oxygen which are harmless elements.
Sulfur dioxide undergo covalent bonding as both elements sulfur and oxygen are non-mestal.

Environmental Effects: Sulfur dioxide and nitrogen oxides are the major precursors of acid rain, which has acidified soils, lakes and streams, accelerated corrosion of buildings and monuments, and reduced visibility. Sulfur dioxide also is a major precursor of fine particulate soot, which poses a significant health threat

Sulfur Dioxide:

It is produced by volcanoes and in various industrial processes. Since coal and petroleum often contain sulfur compounds, their combustion generates sulfur dioxide unless the sulfur compounds are removed before burning the fuel. Further oxidation of SO₂, usually in the presence of a catalyst such as NO₂, forms H₂SO₄, and thus acid rain.

Sulfur:

It is an abundant, multivalent non-metal. Sulfur, in its native form, is a bright yellow crystalline solid. In nature, it can be found as the pure element and as sulfide and sulfate minerals. It is an essential element for life and is found in two amino acids: cysteine and methionine. Its commercial uses are primarily in fertilizers, but it is also widely used in black gunpowder, matches, insecticides and fungicides.

Oxygen:

In nature, oxygen is a gas with no color or smell. Oxygen is a very important element because it is a part of the air you breathe and the water you drink. Because of this, oxygen supports life. All living things (including humans) need oxygen to live , and is a highly reactive nonmetallic element that readily forms compounds (notably oxides) with almost all other elements

The effects of sulfur dioxide are:

• It is the major component of acid precipitation
• It corrodes metals
• It is toxic to plants
• It combines wit moisture in the nose and lungs to create irritation

sources:
http://www.cleanairtrust.org/sulfurdioxide.html
http://wiki.answers.com/Q/How_is_how_is_sulphur_harmful#ixzz1DnklgZw1 http://en.wikipedia.org/wiki/Oxygen
http://simple.wikipedia.org/wiki/Oxygen http://en.wikipedia.org/wiki/Sulfur http://en.wikipedia.org/wiki/Sulfur_dioxide