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GCSE: Classifying Materials
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How to tell if something is ionic
- 1 Ionic compounds have strong electrostatic attractions between their positive and negative ions. These take a lot of energy to break, so will have a very high melting and boiling point.
- 2 Ionic compounds can conduct electricity when dissolved in solution as their ions are free to move and carry charge. When they are solids, however, their ions are held in a fixed lattice so they cannot move and conduct electricity.
- 3 Ionic compounds are soluble in polar solutions like water. They are insoluble in organic solvents like cyclohexane.
- 4 Ionic compounds all form crystal salts. If these are hydrated they will often be brightly coloured. If they are not hydrated they will usually be transparent or white.
- 5 Ionic compounds are made from metal cations bonding to non-metal anions in a giant lattice.
How to tell if something is a giant covalent
- 1 Giant covalent compounds are held together by incredibly strong covalent bonds. These take a lot of energy to break, so will have an incredibly high melting and boiling point.
- 2 Giant covalent compounds do not have anything to carry charge (such as ions or delocalised electrons) so will not conduct electricity. The exception to this rule is graphite, as this has delocalised electrons so can conduct.
- 3 Giant covalent compounds are insoluble in both polar and non-polar solvents. This is because their strong covalent bonds are too strong to be broken by the solvent.
- 4 The three main forms (allotropes) of carbon that are giant covalent compounds are diamond (a beautifully shiny rock), graphite (which looks like the tiles on our roofs) and fullerines. Fullerines have a “football” shape.
- 5 Apart from allotropes of carbon, the most commonly occurring giant covalent compound that crops up in exams is SiO2.
How to tell if something is a simple covalent
- 1 Simple covalent compounds are held together by weak van der Waals forces. These take little energy to break, so have a very low melting and boiling point.
- 2 Simple covalent compounds do not have anything that can carry charge (like ions or delocalised electrons), so they cannot conduct.
- 3 Simple covalent compounds are soluble in non-polar solvents, and insoluble in polar solvents like water.
- 4 Due to their low melting and boiling point, most simple covalent compounds are liquids or gases at room temperature. The halogens will give coloured gases- Cl is pale green, Br is orange, I is an almost black solid which sublimes to a purple gas.
- 5 Simple covalent compounds are made from a non-metal bonding to a non-metal.
- Marked by Teachers essays 10
- Peer Reviewed essays 15
A long time ago, scientists studied the elements Potassium, Sodium and Lithium and found that they all react alike with water, oxygen and chlorine to produce similar compounds. It had been shown that lithium has a lower rate of reaction than sodium, whereas potassium has a higher rate of reaction than sodium. When you link this with their atomic masses, sodium is yet again the middle element! This same pattern is repeated with other groups of threes, for example: Bromine, Iodine and Chlorine, which eventually became known as the Law of Triads.
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In order for any reaction to happen, the particles must first collide. If the concentration is higher, the chances of collision are greater, thus resulting in a greater rate of reaction. Method: First I filled five different test tubes with the five different concentrations of the acid. I measured all of them to 20cm3. Then I collected five different pieces of zinc, and then weighed them on a scale. I recorded these results for later use. I made sure the temperature of the acids was the same using thermometers. I placed each piece of zinc in a different concentration and started the stop watch.
- Word count: 711
How are elements arranged: The Periodic table is a display of all the elements that we know of, it is shaped like a rectangular box. The elements are sorted accordingly depending on their atomic structure, which shows their properties. They are arranged by increasing atomic number, which shows the amount of protons a certain element. Some elements have long names, that is why all elements are given an abbreviation which is shared throughout the scientific world. The atomic number could be found at the bottom left-hand corner of the abbreviation.
- Word count: 677
In this essay I will be focussing on two individual scientists and what contribution they made to todays model of the atom, and how having a thorough understanding of the atom has been both an advantage and disadvantage in todays society.4 star(s)
This ray is also known as an 'electron gun'. Thomson constructed his own electron gun and performed experiments on the rays given out of his gun. Through his experiment he found the rays were attracted to a positive charge. Thomson accurately deduced that the rays themselves must be negatively charged because opposites attract and if they were positive then they would repel. He performed additional experiments where he proved that it would take about 2000 electrons to equal the weight of the lightest atom on the periodic table of elements, hydrogen.
- Word count: 939
Pure aluminum, a silvery-white metal, possesses many desirable characteristics. It is light, it is nonmagnetic and nonsparking, stands second among metals in the scale of malleability, and sixth in ductility.In its early days aluminium was too expensive to be used by everybody. It wasn't until a few discoveries in the 1800s that made extraction of aluminium cheaper. As it became easy to extract aluminium from aluminium oxide and extract large amounts of it from bauxite, hence began an era of cheap aluminium.
- Word count: 474
This is called a redox reaction. (Science diagrams) Method 1. Put 1.5g of malachite powder into a large test tube and heat it gently until it turns black and stops rising in the test tube. 2. Allow the tube time to cool 3. Add 1.5g of carbon powder and mix well. 4. Heat the mixture strongly until it turns red and you can see some of the pink copper. 5. Let the mixture cool. 6. Separate the copper from the waste by half filling the test tube with water and pouring the mixture into a beaker of cold water.
- Word count: 644
Buckminsterfullerene was not discovered because people wanted to discover it: it was discovered purely by chance. Scientists were trying to understand about the absorption of interstellar dust and the theorised that they must have long chains of atoms. Further research with a molecular beam proved their theory right (to some extent), as there were not long chains, just one big ball - hence the nickname "Bucky balls". The other allotropes of carbon (diamond and graphite are giant molecular structures whilst Buckminsterfullerene is simple molecular.
- Word count: 543
Determining unknown solutions. Questions: Are there any silver, strontium, and/or zinc ions in the number 3 unknown solution
On the basis of solubility, we can determine what chemical ions solution has. For example, this #3 unknown solution have silver, strontium or zinc ions. When we put Cl- with Ag+ Pb2+ Ti+ Hg+ and Hg2+ together, they all have very low solubility, and product precipitate. This solution only probably has Ag+ in Ag+ Pb2+ Ti+ Hg+ and Hg2+, so if we put Cl-- into the solution and product precipitate. It means there is Ag+ in this solution. By parity of reasoning, if we put OH- into the solution, and product precipitate. It means there is Zn2+ in the solution; and also if we put SO42- into the solution, and product precipitate.
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Identifying unknown substances. The test that we did was a flame test, negative ion test and a alcohol test. We also did chromatography to find out which technician labelled the bottle.
Not completely, of course, of even near complete 6. full- about half an inch of water 7. And wait There are two parts in naming a chemical Name of the chemical negative ion Flame test To find the first part of the name of the chemical you have to do a flame test. A flame test is used to indentify the names of the metal by the colour that is produces. 1. Use a wire called nichrome so that the wire does not produce colour to the flame 2. dip a nichcrome wire into the hydrochloride acid to clean it 3.
- Word count: 993
Elemental mercury exists as a silvery liquid and an odourless vapour at room temperature. It is eliminated in urine, faeces, saliva, and sweat and by exhalation when it is taken in by the body. How is Hydrochloric acid disposed of: - Small amounts of dilute hydrochloric acid can be flushed down a sink with a large quantity of water, unless local rules prohibit this. Larger amounts should be neutralised before disposal. Concentrated acid should not be flushed down a sink but should be neutralised first.
- Word count: 925
Distilled water was used to dampen the red and blue litmus paper 3. Matches was used to light the Bunsen burner 4. Using the flame of the Bunsen burner the splint was lit and then blown out leaving a glowing splint 5. The tongs was used to hold the test tube "A" over the lit Bunsen burner and the blue and red litmus paper was held at the opening of the test tube 6. The glowing splint was then placed inside test tube "A" 7.
- Word count: 532
and xylene cyanol (C25H27N2NaO6S2) are separated through the use of water as a solvent. Aim-To determine which dye in screened methyl orange is more soluble in water. Apparatus-screened methyl orange, chromatography paper (10cm X 2.5cm), 250cm3 beaker, fine dropper, retort stand. Method- 1. A horizontal line was drawn on the chromatography paper 1.5cm above the bottom line 2.
- Word count: 400
Find the total mass of the magnesium ribbon, crucible and the lid. Note the appearance of the magnesium. 3. Place the crucible (with the lid on) on a pipe clay triangle supported on a tripod. Heat the crucible with a strong Bunsen burner flame. 4. Lift the lid carefully with tongs every 10 seconds to let the air enter the crucible. Keep heating the crucible until the reaction is complete.
- Word count: 555
The clarity of diamonds makes it extremely suitable for making materials that require pure and clear screens to reflect light. Since synthetic diamond is the cheapest and hardest material in the world, making it worth the cost of producing. There are two ways to make synthetic diamonds. With high pressure and high temperature or with chemical vapor deposition, a method of creating a carbon plasma on top of substrate onto which the carbon atoms deposit to form diamond. Diamond, with its hardness and clarity, has influenced our lives in many ways.
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Tine layer and paper chromatography experiment. The aim of the investigation was to determine the quality of the water that contains chemical dye pollution. To begin the investigation firstly we put a line on the tine layer paper
These two methods is a useful because it is relatively quick and requires small quantities of material. The aim of the investigation was to determine the quality of the water that contains chemical dye pollution. To begin the investigation firstly we put a line on the tine layer paper and carefully a spot on the stationary phase. In to the beaker mixing two different chemical, methanol and ethanol then placed the paper in to the beaker. And leave the paper about 10 minute, until the solvent move up. Finally different components of the mixture moved up at different rates.
- Word count: 773
Water is commonly used as a solvent; this dissolving process is called hydration. The heat involved in a chemical reaction, at constant pressure is referred to as enthalpy and usually refers to the"...amount of energy released for one mole of the ion dissolved in a large amount of water forming an infinite dilute solution in the process."1 Enthalpy change in a solution is shown by the equation where the overall positive or negative energy depends on the values of each trial.
- Word count: 700
50cm3 of hydrochloric acid is added to beaker with eggshell and stirred with glass rod 5. Stirring is continued until eggshells stop producing bubbles indicating that no more eggshell can be dissolved 6. Mixture is filtered for a day and the residue of eggshell is left in filter paper 7. Residue is left to dry ,and the mass of the filtrate along with the residue and dry filter paper is recorded 8. The residue is removed and the mass of the filter paper is recorded. Results Mass of eggshell=27.55g Mass of filter paper + egg-shell residue= 15.6g Mass of filter paper without residue=2.06g Calculations 1.
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Eventually the particles are evenly spread and the concentration is equal. * Diffusion does not happen in solids * Diffusion is the way we smell things from far away The Atom * Atomic (proton) number gives the number of protons * An atom is neutral so the amount of protons and electrons are the same * Mass number gives number of protons and number of neutrons * Isotope are elements that can exist in more than one form * Atoms are found as compounds in nature because they are unstable without a full outer shell Substances with ionic bonding * Usually involves a metal and non metal * Element far apart
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Apparatus Equipment * Retort stand * Universal Clamp * Fishing Wire * Weights (100g) * Clamp * Mat For Floor Safety * Make sure there is space to work * Keep clear of mat so the weight doesn't hit your feet * Clear the area Method 1. Put the retort stand on the edge of the table 2. Clamp it down so it is unable to topple over 3.
- Word count: 506
There are many things in life that no matter how hard we try we can not explain. If God exists he provides an answer and explanation to all of these mysteries. This also links in with the idea that life is so complex and diverse many people including myself find it hard to get our heads around the fact the world and everything in is the result of an accident or freak of nature. The fact that the Big Bang just occurred and everything formed is quite a difficult idea to comprehend.
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Watch Glass 8. Stop Clock 9. Table of results 10. Catalyse - 6.25%, 12.5%, 25%, 50%, 100% Method: 1. Firstly, we hole punched 15 holes using the filter paper. 2. Next, we filled the tube half way with 100% hydrogen peroxide. 3. Then we dipped the discs of filter paper into the catalyse which was in a watch glass. 4. After that, we picked the discs from the catalyse using a pair of tweezers and soaked it with catalyse and placed it at the bottom of the tube which was filled with hydrogen peroxide. 5. Next we timed how long it took for the discs to rise to the surface of the tube with a stop watch.
- Word count: 571
This is the reason why they will collide more often. Equipment Substances that we're going to use Pipette Hydrochloric acid Stopwatch Sodium thiosulphate Spotting tile Water Conical flask Funnel Burette Method 1. Set up apparatus as shown in the diagram. 2. Measure 25cm3 of hydrochloric acid and pour into conical flask. 3. Add 25cm3 of 0.2 mol dm-3 of Na2S2O3 to hydrochloric acid and immediately start stopwatch. 4. When the cross disappears stop the stopwatch. 5. Record the results. 6. Repeat steps 1-5 three more times. 7. Repeat step 1-6 for 0.4, 0.6, 0.8, 1.0 mol dm -3 Na2S2O3.
- Word count: 803
Hypothesis: I base my prediction on my belief that when the voltage is low, the current is weak and therefore less can be separated. In the same way I believe that when the voltage is high, the current is strong so more of the solution can be separated. In electricity opposites attract. Therefore the metals ions, that are positively charged, move towards the cathode which is negatively charged and supplies electrons. Once at this stage, the metal ions collect electrons and become neutral atoms.
- Word count: 980
Measure the weight of the empty crucible with the lid on 3. Take a specified length of the magnesium ribbon, that was assigned to your group, and then coil it 4. Put the coiled magnesium ribbon in the empty crucible 5. Measure the weight of the crucible with the magnesium ribbon inside and with the lid on 6. After measuring find the weight of the magnesium 7. Put the clay triangle on the tripod stand 8. Put the crucible on the tripod stand 9. Switch on the Bunsen burner and let the crucible heat 10.
- Word count: 544