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ScienceNet is a World Wide Web resource database in Science. It is a community service project by Science Centre Singapore, supported by Nanyang Technological University and National University of Singapore.

We offer free electronic access to various topics in Science and Technology. Feel free to browse through our database and see if we have the answers to your questions.

Physical Sciences - Inorganic Chemistry/ Periodic Table
Q20360 :	Is carbonic acid an organic or inorganic acid? I've got mixed answers from the websites, some listed it as an organic while others as inorganic.
Q20328 :	what effect does the pH on the solvent extraction of metal?
Q20211 :	Why is there neutron in some atoms but none in, example, hydrogen?
Q20016 :	Carbon monoxide is a reducing agent just like sulphur dioxide. One difference between them is that carbon monoxide is insoluble in water while sulphur dioxide is very soluble in water. Question is whether carbon monoxide is able to turn the colour of aqueous acidified potassium dichromate from orange to green?
Q19932 :	Why is helium kept in the category of p-block element though its differentiating electron enters the s-orbital?
Q19600 :	What is the chemical name for ozone?
Q19388 :	Why is sulphuric acid sold commercially as 98% concentration? And why is hydrochloric acid sold commercially as 37%, not and 100%?
Q19111 :	What are isotopes? How are they formed? Or are they just naturally? Please give some examples of isotopes.
Q18909 :	What are the two products formed from the reaction of fluorine and ozone?
Q18805 :	What are the 5 heaviest metals?
Q18380 :	What is the name of the British chemist who developed a process for extracting nickel from ore?
Q18325 :	What is the history of aluminium extraction and uses?
Q18324 :	Why does iodine sublime? What special property does it have that other elements in the same group don't?
Q18290 :	What chemical reactions take place in a catalytic converter?
Q17879 :	How is sodium hydroxide manufactured and where is it used?
Q16142 :	Copper sulphate solution contains H⁺, SO₄^2-, OH^-, Cu²⁺ and H₂O. Why does this allow it to conduct electricity?
Q15891 :	What is the ratio Pd/Au in the commonly found white gold in jewellery stores?
Q15839 :	What does the element mercury react with other elements?
Q15633 :	Why is silver nitrate solution unstable? What reactions occur during its decomposition?
Q15610 :	What are some compounds of lithium and what are their chemical formulas and uses? Please and thank you!
Q15605 :	Gold and platinum are unreactive metals. Under what conditions do they react to form compounds?
Q15505 :	Is the atomic radius of noble gas larger or smaller than that of halogen? Some books said that they should be smaller and some said that they should be larger. What kind of radius should be used for comparison -- covalent radius, van der Waals radius or ionic radius?
Q15327 :	What are the trends in the Periodic Table across the period and down the family?
Q15319 :	What is neon and what is it used for? When was it discovered? Who discovered it?
Q15273 :	How is copper sulphate (CuSO₄) used in real world applications?
Q15236 :	What is transition metal?
Q15073 :	Where does the metal type of potassium come from and where is it found?
Q15004 :	Sulphate and thiosulphate: in what properties do they differ?
Q14936 :	At what temperature does mercury freeze?
Q14735 :	Where can I find all the information I need for my science project, like the atomic mass of the element zinc, or its number of protons and neutrons?
Q14564 :	Helium is an inert gas that does not react with other substances to form compounds. Would it be correct to say that helium has no chemical properties?
Q14456 :	What is the difference between valency, oxidation state and oxidation number? What is the valency of carbon and oxygen in the compound carbon monoxide?
Q14444 :	How many carbon atoms are there in a carbon molecule?
Q14336 :	Hi, I just like to know about silicon dioxide's structure and investigate the properties of carbon and graphite and why they are so different from each other while both are composed of carbon atoms in terms of their covalent structure.
Q13449 :	Is hydrogen a metal? Why is it that in different periodic table the hydrogen is placed at a different place? This has been bothering me for a long time. Hope you can help me with it.
Q12479 :	How is hydrogen peroxide decomposed? What metal oxides can be used as catalysts?
Q11930 :	What is an amphoteric oxide?
Q11801 :	How many protons, neutrons and electrons does a zinc atom have?
Q11465 :	While electrolysing copper sulphate with carbon electrodes I noticed a black substance being deposited at the bottom of the beaker. What could this be? I am told that the carbon electrodes are considered inert and so do not react.
Q11457 :	What is the method of preparing potassium iodide?
Q11452 :	Can you please give me the uses of sulphur?
Q11346 :	What is the freezing point of lithium in Celsius? How was lithium discovered?
Q11337 :	Could you possibly tell me a brief description of nitrates and their properties? I am trying to find out about silver nitrate, so if you have any information on that, I would really appreciate it.
Q11328 :	How do potassium, magnesium, silicon, lead, uranium, etc. look like? Where can I find pictures of different elements?
Q10932 :	How are aluminium alloys made?
Q10881 :	What is an octet? How does it deal with atoms and/or the periodic table of elements?
Q10824 :	How can I break down salt into sodium and chlorine and have two pure substances?
Q10576 :	What is Ostwald process?
Q10459 :	Who discovered the element mercury and the element platinum? When were they discovered?
Q10331 :	I have read that sulphuric acid is used as a drying agent. Is there any truth in that?
Q10203 :	Who discovered the element zinc and when?
Q10062 :	What are some uses of the element caesium or cesium?
Q9999 :	What are the melting points of Tin(II) iodide and Tin(IV) iodide?
Q9968 :	What are the chemical properties of elemental caesium? How is caesium stored?
Q9963 :	I would like to know what elemental mercury looks like. I cannot find any picture of it.
Q9756 :	What are the uses of sulphuric acid, ammonia and nitric acid?
Q9734 :	Which element has the lowest melting point?
Q9667 :	Why are the "bits" of the soldering irons made of copper?
Q9572 :	I understand that rusting normally occur in steel (iron + carbon). Recently, I read that wrought iron (almost 100% iron if I am not wrong) do not rust. Why is this so? Or have I misinterpreted?
Q9549 :	Why are transition metals used as catalysts? What properties do they have?
Q9520 :	Can electrolysis be applied at cryogenic temperatures? For example, can liquefied air be separated by electrolysis?
Q9514 :	What will happen when aqueous lithium chloride undergoes electrolysis using copper electrodes?
Q9508 :	What is the man-made chemical element einsteinium (atomic number 99) used for today?
Q9506 :	How is iron purified and what are its uses?
Q9501 :	What is the chemical composition of the material used in silicone implants?
Q9438 :	Would it be possible to find out some of the physical properties of carbon dioxide like melting point and boiling point, etc.?
Q9348 :	What are double salts and complexes?
Q9206 :	I was told that the elements in the periodic table are arranged, having their sizes decrease accordingly, from Group I to Group VII and that the atom of the element in Group VIII become bigger again. Why is it so?
Q9178 :	What are the reasons for the manufacture of sulphuric acid and how does it reflect the economy of a country ?
Q9153 :	How is sodium kept? Why is it kept that way?
Q9148 :	Why is sodium + water = sodium hydroxide + hydrogen instead of sodium + water = sodium hydroxide + oxygen?
Q9068 :	What is carbon disulphide, CS₂? Can it be used in fertiliser and medicines?
Q8999 :	What are the reactions of sodium hydroxide solution and copper(II) sulphate solution being mixed together?
Q8898 :	What is the shape of cadmium sulphide crystals?
Q8833 :	What is zinc blende -- its formula, chemicals properties and uses?
Q8787 :	How is sodium silicate manufactured?
Q8722 :	What metals have a lower melting point than tin?
Q7894 :	What element has the highest boiling point -- carbon, hydrogen, uranium or tungsten?
Q7846 :	What does the element arsenic look like?
Q7832 :	What exactly is the Haber process?
Q7827 :	What does the periodic table look like?
Q7780 :	What are the physical and chemical features of platinum? How was it discovered and who discovered it? What is it used for?
Q7616 :	What are the physical and chemical properties and uses of sulphuric acid?
Q7515 :	What is the mechanism that explains the growth of some hydrated salt crystals in sodium silicate? Why do different salts grow at different speeds?
Q7361 :	Where does iodine come from and what are the common uses of it?
Q7287 :	What is the melting point of table salt?
Q7241 :	I want to know more about the chemical element einsteinium (atomic number 99). I cannot find that much information on the element. I was wondering if you could provide interesting facts about einsteinium.
Q7022 :	Where is fluorine found in nature? How is fluorine used?
Q6939 :	What is the boiling point of mercury?
Q6818 :	What are some compounds that contain Uranium? How is uranium obtained?
Q6751 :	What is the weight of various metals; such as gold, silver, zinc, iron? Is there a chart listing from the heaviest to the lightest?
Q6631 :	Who invented the periodic table?
Q6616 :	What is isotope? Why are deuterium and tritium called isotopes of hydrogen?
Q6592 :	Could you please explain to me what activated carbon is, how it works and what it is used for?
Q6411 :	Please tell me some uses of sulphur dioxide.
Q6333 :	What is salt exactly? I heard once in Junior High School that it is a metal and a deadly gas. Please help settle the dispute I have with a co-worker on the subject. I could not find the answer to my question in those listed in the ScienceNet.
Q6119 :	Based on seeing that heating sulphur caused it to form allotropes and general knowledge of the periodic table, what other elements that might be expected to form allotropes?
Q6014 :	What is the density of NaOH?
Q5950 :	I am curious why the noble gases such as neon and argon do not exist as molecules?
Q5689 :	What are the chemicals used as tear gases?
Q5486 :	Why do things rust? Is only water necessary for objects to rust, or are there other things in the development of rust?
Q5402 :	Who first discovered the element arsenic?
Q5193 :	What is the breakdown of carbon-14? What are all the half lives until it reaches nitrogen?
Q5113 :	What is an anhydride?
Q5097 :	Why do transition elements have different oxidation states?
Q5029 :	What is the melting point of platinum?
Q4993 :	Can you please provide some information on the compound XeOF4?
Q4911 :	What does iron (Fe) look like? What are some chemical properties of iron?
Q4852 :	If you have a solution containing tin hydroxide, and then add excess hydroxide ions, why does the precipitate redissolve? Is a complex formed and what is this?
Q4820 :	What is the most common isotope and relative abundance of nitrogen?
Q4728 :	What is the pattern of reactivity with water among the alkali metals?
Q4652 :	What are the uses of the noble gases?
Q4559 :	What is the most common eutectic alloy?
Q3996 :	May I know why does the atomic size of elements decrease across the period of the periodic table?
Q3991 :	Although sodium has metallic bonds, it has a low melting point. Why is it so? Why is sodium more reactive than lithium?
Q3989 :	Who discovered the element hydrogen and when was it discovered?
Q3850 :	Which element has the highest melting? Which element has the lowest melting point? Besides mercury, what other element is a liquid at room temperature (298 K)?
Q3770 :	How do I separate sulphur dioxide into its two components, sulphur and oxygen? I request any information or reference books that you may know of to assist me.
Q3669 :	What are the known forms of water, other than heavy water? I understand that there are others such as H3O4 -, with unusual properties.
Q3565 :	Silicon dioxide exists as a giant molecular structure. At very high temperature, the strong covalent bonds of the compound can be broken and the lattice structure breaks down. When this happens the atoms of Si and O are formed. Hence, I think, the compound does not melt down and form liquid silicon dioxide but vaporises/ sublimes. However, very often in the Cambridge 'A' level examination, students are asked to predict the boiling point of silicon dioxide. In the examiner reports, it is recorded that silicon dioxide has very high boiling point, the reason being that strong covalent bonds are broken in the boiling process. I find it hard to accept this explanation as boiling is a process whereby a compound changes from the liquid state to a vapour state and silicon dioxide does not have a liquid state. My questions are: (a) Does boiling also mean changing from a solid state to a liquid state? (b) Some chemicals (e.g. carbon dioxide, ammonium chloride, iodine, etc.) sublime. Sublimation is usually explained from phase diagram. Can sublimation be explained from the bonding or molecular point of view? I greatly appreciate your help. Thank you.
Q3409 :	What is the boiling point of tellurium?
Q3385 :	Azo compounds contain no transition elements but why are they coloured?
Q3381 :	What causes hydrogen peroxide to bubble when it comes into contact with certain things, such as an open wound?
Q3344 :	What is the process for making calcium nitrate. Is there a simple process to use calcium carbonate for this process? Thanks.
Q3220 :	Please name those elements of the periodic table which are named after scientists.
Q3205 :	Why is it that metallic bonds exist in compounds such as tungsten carbide?
Q3191 :	What is the chemical formula of the crystal formed from nickel sulphate and potassium sulphate?
Q3117 :	How and why is it that chemical properties of concentrated sulphuric acid and diluted sulphuric acid differ? What are the different uses of each?
Q2805 :	Ionic compound is formed between metal and non-metal. Aluminium is a metal and chlorine is a non-metal. Why is it that books say that they react to form a covalent compound? Please elaborate.
Q2640 :	What is the correct formula for rust? Why is it that some books say it is Fe₂O₃ while others say it is Fe₃O₄?
Q2634 :	What are the colour of tin nitrate and other compounds of tin? Where can I get information on the colours of compounds?
Q2273 :	What substance (other than water) expands on freezing and has an abnormally high boiling point?
Q2270 :	What are oxidation numbers?
Q1987 :	Noble gases are stable gases, which means that they do not react at all. But, recently I read an article saying that 2 men have actually created a compound using these noble gases! How was that possible?
Q1914 :	How does carbon react (combine) with other elements?
Q1607 :	What would happen when you put 2g of iron filings and 2g of iodine crystals in a closed container and put it over a low flame?
Q1331 :	If helium is similar to hydrogen, then why is helium inert and hydrogen highly reactive?
Q1224 :	Arsenic forms an oxide, As₂O₃. This oxide reacts with water to form an acid. Deduce a likely formula for this acid. Please help me.
Q1208 :	Can ammonium salt react with acids? If so, what would we get? Would we get ammonia gas?
Q1201 :	Nuclear reactions are caused by spitting the nucleus of uranium. Can electrons be split? If possible, what is the resultant of this action?
Q1001 :	What are the by-products when aqua regia reacts with metal, e.g. gold?
Q820 :	Gaseous nitrogen contains covalent molecules. Why might this structure lead you to expect nitrogen to undergo addition reaction?
Q620 :	How does uranium exists in nature? Is it possible for it to form a salt? What is the chemical name and formula of that salt?
Q594 :	I would like to know if the chemical name for rust is iron(III) oxide. If this is the chemical name, then what is the chemical formula for rust?
Q422 :	Can you please show me the atomic structure of carbon monoxide and nitrogen dioxide in terms of covalent bonds?
Q418 :	What is ozone?
Q417 :	What is the best approach for the best salt preparation method?
Q347 :	a) Hydrogen is a non-metal. It has one electron and therefore it is in the Group 1 of the periodic table. However Group 1 is for the metals. How is that possible? b)Water is a covalent compound. During electrolysis, it ionises into H⁺ ion and OH^- ion. It is not an ionic compound. Why can water be ionised?
Q238 :	What are the 4 chemical properties of metals? Does Magnesium react violently?What does it form, hydroxide and __________?
Q166 :	What is valency?

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