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50 Cards in this Set
- Front
- Back
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What is the periodic table?
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The periodic table of the elements developed as an attempt to classify the elements. It arranges them in a pattern according to their properties
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What was a major problem with some of the early periodic tables?
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Early versions failed to take into account of the fact that not all of the elements were known at that time
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Who was the key man who revolutionised the periodic table?
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Dmitri Mendeleev. It took account of unknown elements and provided the basis for the modern periodic table.
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How is an elements place in the periodic table determined?
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By its atomic (proton) number
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What determines the chemical properties of an atom?
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The number of electrons in the highest energy level. E.G. If the arrangement is 2,8,8,2. It is in group 2 (last number). If its arrangement is 2,8,8,7 it is in group 7
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How can we explain trend in reactivity as we go down a group?
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Because of the number of energy levels in the atoms
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What are the elements in group 1 of the periodic table called?
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The alkali metals
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When alkali metals react with water they produce ________ and _______
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Hydrogen and an alkaline solution containing the metal hydroxide
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The reactivity of the alkali metals increases/decreases as we go down the group
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increases
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What kind of molecules are the halogens?
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Diatomic (e.g. They always have a little two after their element. E.g. Cl2, Br2, I2)
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When halogens form ions, what is their charge?
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A single negative charge. Because they gain an electron. So the ion for Cl2 would be Cl
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What kind of compounds do the halogens form?
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COVALENT compounds. They share electrons with other non-metals.
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The reactivity of the halogens increases/decreases as you go down the group
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decreases
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What kind of melting points/density do the transition elements have?
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High MP and high density.
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What can you say about the conduction of heat electricity in the transition metals?
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They are very good conductors of them
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Do the transition metals react vigorously with oxygen or water?
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No. That's the alkali metals :)
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What ions do acids produce in aqueous solutions?
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H+ ions.
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What ions do alkalis produce in an aqueous solution?
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OH- ions.
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What defines a strong acid or base?
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One that completely dissociates (100% ionised in water). A weak one is one that only partially disociates
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An acid is a proton _____
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Acid = donor
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A base is a proton ________
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Base = acceptor
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What is titration?
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The method used to measure accurately how much alkali is needed to react completely with a known amount of acid (or vise versa)
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How can you tell when the titration reaction has been completed?
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When the indicator changes
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Number of moles = ?
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Volume (cm3) * concentration (mol/dm3)
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What do solubility curves show?
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How the solubility of a substance changes with temperature
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How the solubility of a substance changes with temperature
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Calcium and magnesium salts
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Ca/Mg decompose to form _____ when the water is heated
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scale
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Hard water is beneficial/detrimental to human health?
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beneficial
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How can hard water be softened?
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By removing the salts that produce scum and scale. This can be achieved by adding washing soda or using an ion-exchange resin to remove the ions
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What would you expect drinking water to have little of?
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Dissolved substances and microorganisms
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How is water made fit to drink?
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By adding chlorine to kill bacteria
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How can you make pure water?
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By distilling it
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Are many covalent compounds soluble in water?
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No
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What is a saturated solution?
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Where the maximum amount of solute will dissolve in a solution at a given temperature.
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When the temperature increases, the solubility of solids increases/decreases
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increases
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As the temperature rises, what happens to the solubility of gases?
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It decreases
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What colour flame does lithium have?
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Bright red
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What colour flame does sodium have?
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yellow
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What colour flame does potassium have?
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lilac
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What colour flame does calcium have?
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brick red
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What colour flame does barium have?
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apple green
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What solution can be used to identify different metal ions depending on the precipitate that is formed?
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Sodium hydroxide solution
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What do ammonium ions produce when sodium hydroxide solution is added and warmed?
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Ammonia :)
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How can you identify carbonates?
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By adding a dilute acid, this produces CO2 gas.
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How do you identify halides?
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By adding nitric acid and silver nitrate solution, this produces a precipitate of silver halide
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How do you identify sulfates?
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By adding hydrochloric acid and barium chloride solutin to produce a white precipitate of barium sulfate
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How do you identify nitrates?
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By adding sodium hydroxide solution and a little aluminum powder to produce ammonia gas
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What happens to organic compounds when we heat them?
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The burn or char, inorganic substances do not
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What can be used to analyse and identify the chemical elements in a sample?
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Atomic absorption spectroscopy (AAS)and mass spectrometry
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How can you separate compounds in a mixture?
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By using chromatography
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