"Use www.weebly.com to set up a blog. It's free and should be fairly self-explanatory. If you have any problems doing this don't stress - you can let me know next lesson.
Listen to the following programme:
http://www.bbc.co.uk/programmes/b01rgm9g
It is about 45 minutes long and, referring to pages 12 and 13 of your book, I would like you to make your first blog post about this radio programme.
What is so special about water?
How was the chemistry of water discovered?
What are scientists still trying to find out about water?
It's a reasonably big homework so I'm giving you time. Don't leave it till the last minute!
Due 15th September"
What is so special about water?
Water is an incredibly fascinating molecule with many different qualities and facts that make it so interesting. Did you know there are 330 million cubic miles of water in the atmosphere and it is the second most common molecule on the planet (after hydrogen)? Water dominates our planet and covers much of the globe, around 70%, and is necessary for life. The most curious thing about water is perhaps the juxtaposition between the abundance and the perceived simplicity of the molecule and the actual complexity of the molecule.
Water is a very strange material, it is able to store a huge amount of energy, compared to other liquids, the energy capacity of water is magnitudes higher then other common liquids (this being why it is still used in heating). Water's density also changes remarkably with temperature. Water has a maximum density at 4 degrees and colder or hotter than this the density decreases. This creates the phenomenon of ice, solid water, being able to float on water. This is because when the water solidifies the water is arranged in a hexagonal way this spreads out the molecules meaning a lower density. In ice there are four oxygens touching eachother at any one time this means there are holes / channels going through ice that can contain smaller gases (atomically) for example methane and hydrogen
Water, on top of that, is an excellent solvent, For example table salt, sodium chloride has a melting point of 800 degrees however when placed in water it dissolves. The positive ion of salt is surrounded by negative ion of the water. Some of the water acts as a solvation shell. These shells, in this example are essentially the water molecules circling the ions and allowing them to be dissolved. It is so good at dissolving due to the unique polarity of the molecule by pulling them apart. The unique polarity of water is that it is a dipole, this means that though the overall charge of covalent bond is 0 the charge is skewed due to the oxygen pulling the hydrogen electrons closer to itself then the hydrogen. This means that the oxygen is ever so slightly negative ( shown by the greek sign delta, then a negative sign ). This is the contributing factor for many of the properties and quirks water has, This is why water is so special.
How was the chemistry of water discovered?
Water was "discovered" in the chemical revolution which began in the 17th century. The chemical revolution was "the early modern reformulation of chemistry" that included key discoveries such as the law of conservation of mass and oxygen theory of combustion Antoinne Lavoisier was key in the development of understanding the water molecule as we know it. It was originally believed that water was infact an element, much like carbon or helium. Now, much like the earth being flat, this notion would be regarded as foolish and that water is of course a compound. The first person to start the discovery was Antoinne Lavosier, a famous French chemist born in 1743. It is really a 50 year long conquest to discover water. The breakthrough was in fact an Englishman, William Nicholson, who using electrolysis on a sample of slightly acidic water found there to be effervescence of two gases. After identifying the gases to be oxygen and hydrogen, he found them to be to be in a 2:1 ratio. 2 being the hydrogen and 1 being the oxygen, this disproved the popular theory of water being an element as it was made up of more then one thing. Despite this discovery, much controversy remained over the weighing of the elements and whether there was actually a 2:! ratio. Despite this happening at the turn of the 18th century this problem was still prominent well into the 19th century.
What are scientists still trying to find out about water?
The hydrogen bonds can flick on and off every pico second (10 to the -12 seconds). This is because the water molecules are dynamic and collide and shift the hydrogen bonds causing this. However scientists don't know what is actually happening at an atomic level to cause this or what it may look like. Scientists know this is happening as they are able it indirectly using a laser to monitor the formation of the hydrogen bonds. Many other similar molecules such as ammonia (NH3 / H2S) act differently meaning there is very little idea to what is happening to the hydrogen bonds in water.
Scientists also don't know how many types of ice there are, the current number found is 17. The way in which the types of ice differ is subtle yet important all the same. Known as I c (the c being subscript) is the only ice that is naturally found on earth, the other 16 being found at huge pressure inside a lab.The difference in the ice is the arrangement of the molecules, whether there are channels in the ice, the tetrahedral structure etc...
Listen to the following programme:
http://www.bbc.co.uk/programmes/b01rgm9g
It is about 45 minutes long and, referring to pages 12 and 13 of your book, I would like you to make your first blog post about this radio programme.
What is so special about water?
How was the chemistry of water discovered?
What are scientists still trying to find out about water?
It's a reasonably big homework so I'm giving you time. Don't leave it till the last minute!
Due 15th September"
What is so special about water?
Water is an incredibly fascinating molecule with many different qualities and facts that make it so interesting. Did you know there are 330 million cubic miles of water in the atmosphere and it is the second most common molecule on the planet (after hydrogen)? Water dominates our planet and covers much of the globe, around 70%, and is necessary for life. The most curious thing about water is perhaps the juxtaposition between the abundance and the perceived simplicity of the molecule and the actual complexity of the molecule.
Water is a very strange material, it is able to store a huge amount of energy, compared to other liquids, the energy capacity of water is magnitudes higher then other common liquids (this being why it is still used in heating). Water's density also changes remarkably with temperature. Water has a maximum density at 4 degrees and colder or hotter than this the density decreases. This creates the phenomenon of ice, solid water, being able to float on water. This is because when the water solidifies the water is arranged in a hexagonal way this spreads out the molecules meaning a lower density. In ice there are four oxygens touching eachother at any one time this means there are holes / channels going through ice that can contain smaller gases (atomically) for example methane and hydrogen
Water, on top of that, is an excellent solvent, For example table salt, sodium chloride has a melting point of 800 degrees however when placed in water it dissolves. The positive ion of salt is surrounded by negative ion of the water. Some of the water acts as a solvation shell. These shells, in this example are essentially the water molecules circling the ions and allowing them to be dissolved. It is so good at dissolving due to the unique polarity of the molecule by pulling them apart. The unique polarity of water is that it is a dipole, this means that though the overall charge of covalent bond is 0 the charge is skewed due to the oxygen pulling the hydrogen electrons closer to itself then the hydrogen. This means that the oxygen is ever so slightly negative ( shown by the greek sign delta, then a negative sign ). This is the contributing factor for many of the properties and quirks water has, This is why water is so special.
How was the chemistry of water discovered?
Water was "discovered" in the chemical revolution which began in the 17th century. The chemical revolution was "the early modern reformulation of chemistry" that included key discoveries such as the law of conservation of mass and oxygen theory of combustion Antoinne Lavoisier was key in the development of understanding the water molecule as we know it. It was originally believed that water was infact an element, much like carbon or helium. Now, much like the earth being flat, this notion would be regarded as foolish and that water is of course a compound. The first person to start the discovery was Antoinne Lavosier, a famous French chemist born in 1743. It is really a 50 year long conquest to discover water. The breakthrough was in fact an Englishman, William Nicholson, who using electrolysis on a sample of slightly acidic water found there to be effervescence of two gases. After identifying the gases to be oxygen and hydrogen, he found them to be to be in a 2:1 ratio. 2 being the hydrogen and 1 being the oxygen, this disproved the popular theory of water being an element as it was made up of more then one thing. Despite this discovery, much controversy remained over the weighing of the elements and whether there was actually a 2:! ratio. Despite this happening at the turn of the 18th century this problem was still prominent well into the 19th century.
What are scientists still trying to find out about water?
The hydrogen bonds can flick on and off every pico second (10 to the -12 seconds). This is because the water molecules are dynamic and collide and shift the hydrogen bonds causing this. However scientists don't know what is actually happening at an atomic level to cause this or what it may look like. Scientists know this is happening as they are able it indirectly using a laser to monitor the formation of the hydrogen bonds. Many other similar molecules such as ammonia (NH3 / H2S) act differently meaning there is very little idea to what is happening to the hydrogen bonds in water.
Scientists also don't know how many types of ice there are, the current number found is 17. The way in which the types of ice differ is subtle yet important all the same. Known as I c (the c being subscript) is the only ice that is naturally found on earth, the other 16 being found at huge pressure inside a lab.The difference in the ice is the arrangement of the molecules, whether there are channels in the ice, the tetrahedral structure etc...