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153 Cards in this Set
- Front
- Back
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What always happens when elements react? |
Compounds are formed |
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Elements in early periodic tables were arranged in order of their... |
Atomic weights |
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What was the law of octaves, who proposed it, and when? |
The law of octaves was put forward in 1863 by a scientist named Newlands. The theory said that the properties of every 8th element were similar, when in order of their atomic weights |
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Why was Newland's periodic table inaccurate? |
It failed to take undiscovered elements into account |
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Why was Mendeleev's table better than Newland's? |
It took into account undiscovered elements, so elements fit well into their groups |
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Using his periodic table, Mendeleev was able to _____________ the properties of unknown elements, which were later confirmed when they were ___________ . |
Predict, discovered |
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How are elements arranged in the modern periodic table? |
In order of their atomic numbers |
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Elements in the periodic table are arranged in ____________ groups |
Vertical |
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What determines the chemical properties of an element? |
The number of electrons in its outer shell |
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The groups number in the periodic table is equal to... |
The number of electrons in the outermost shell of each element in that group |
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Elements in the same ___________ of the periodic table have similar ___________ properties |
Group, Properties |
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What happens as you move down a group in the periodic table? |
The reactivity of the elements change |
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What determines an element's reactivity level within its group? |
The number of shells it has |
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Why does reactivity change as you move down a group? |
As you move down, the attraction between the nucleus and the outermost electrons decreases, because the number of shells increases. |
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As you go down a group, the metals in it _____________ in reactivity |
Increase |
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Why does reactivity of a metal increase going down a group? |
Because they lose electrons |
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As you go down a group, the non-metals in it _____________ in reactivity
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Decrease |
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Why does reactivity of a non-metal decrease going down a group?
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Because they gain electrons |
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The elements in group one are known as... |
The alkali metals |
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What do the alkali metals produce when they react with water? |
Hydrogen and a metal hydroxide |
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What is a hydroxide? |
An ion of oxygen covalently bonded with hydrogen, with a negative charge |
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When the alkali metals react, they __________ the one electron in their outer shell |
Lose |
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When the alkali metals react and lose their one electron, they become... |
Positive ions |
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The reactivity of the alkali metals ___________ going down the group |
Increases |
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Why is it difficult to use alkali metals? |
They react with air and water |
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Compounds of Alkali metals are often... |
White or colourless crystals |
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What are 5 advantages of the transition metals over the alkali metals? |
They are much stronger, much harder, much more dense, have higher melting points, and are much less reactive |
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The transition metals are good... |
Conductors |
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Transition metals form ions of ___________ charges |
Various |
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Metals always form ___________ ions |
Positive |
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Compounds of transition metals are often... |
Coloured |
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What are three things that transition metals are good for in industry? |
As building materials, as conductors, and as catalysts |
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Elements in group 7 are known as the... |
Halogens |
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When the halogens react with metals to form ionic compounds, they ______ an electron to become __________ ions |
Gain, negative |
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What are the ions of a halogen called? |
Halides |
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A more reactive halogen can __________ a less reactive halogen from a solution of one of its ________ . |
Displace, salts |
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What is hard water? |
Water that contains dissolved compounds such as calcium and magnesium salts |
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Why is it harder for hard water to lather with soap? |
The calcium/magnesium ions react with the soap to form scum |
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Scum is an ______________ solid |
Insoluble |
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How can water become hard? |
Contact with rocks |
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What is temporary hard water? |
Water that produces precipitate when heated |
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What precipitate does temporary hard water produce? |
Scale |
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What is the difference between scum and scale? |
Scum is formed by the compounds dissolved in hard water and soap, scale is formed by heating temporary hard water |
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Why is hard water good for your health? |
The calcium in it is good for your teeth and bones |
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How does scale make heating systems less efficient? |
They cover the heating elements |
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What type of water doesn't produce scale or scum? |
Soft water |
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Temporary hardness can be removed by... |
Heating to form scale |
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Temporary hard water contains _____________________ ions |
Hydrogencarbonate ions |
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What three things do the hydrogencarbonate ions break down into when heated? |
Water, CO2 and carbonate ions |
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After the hydrogencarbonate ions are broken down, the ___________ ions react with the ____________ and _____________ ions to form _________ . |
Carbonate, calcium and magnesium, scale |
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what are two methods of softening both types of hard water? |
And washing soda (sodium carbonate) or and ion-exchange column |
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How does an ion-change column remove hardness? |
The column is packed with a resin that contains sodium and hydrogen ions. When hard water is passed through the column, the calcium and magnesiums ions swap places with the sodium and hydrogen ions. |
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How is drinking water treated to make it safe to drink? |
By filtering it and adding chlorine to kill microbes |
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Why is water not treated by distillation? |
It requires large amounts of energy to boil the water, therefore it would be too expensive |
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Why must the addition of chlorine to water be carefully controlled? |
It is poisonous in large amounts |
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What is one advantage and one disadvantage of hardening water? |
Advantage: Health benefits Disadvantage: Blocks heating systems and makes them less efficient |
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What would be the consequences of not adding chlorine and fluoride to tap water? |
Harmful microbes would infest the water and tooth decay rates would increase |
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When fuels and food ____________ (react with oxygen) the reactions are _________________ . |
Combust, exothermic |
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The amount of energy released in an exothermic reaction is measured in... |
Joules |
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We can use a _______________ to measure the amount of substances released when substances burn |
Calorimeter |
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What is an example of a simple calorimeter? |
A beaker containing water |
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What is specific heat capacity? |
The amount of energy required to heat 1kg of a substance by 1C |
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Why are simple calorimeters inaccurate? |
Much of the energy released is used to heat the surroundings |
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We can calculate the energy change for reactions in a solution by measuring the temperature ___________ and using an equation. |
Change |
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When a _________ is added to a solution in a reaction, we assume that the volume/mass doesn't change. |
Solid |
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What is an energy level diagram used for? |
To show the relative difference in the energies of reactants and products
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The minimum energy needed for a reaction is called the... |
Activation energy |
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Bond breaking is... |
Endothermic |
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Bond making is... |
Exothermic |
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The energy needed to break the bond between two atoms is called the... |
Bond energy |
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Breaking bonds _______ ____ energy |
Takes in |
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Making bonds ___________ energy |
Releases |
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In a exothermic reaction, the energy released by making bonds is ___________ than the energy absorbed when bonds are broken |
Greater |
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In a endothermic reaction, the energy released by making bonds is ___________ than the energy absorbed when bonds are broken
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less |
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Bond energies are measured in... |
kJ/mol |
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How is the total energy change in a reaction calculated? |
1) By calculating the total amount of energy used to break all the bonds of the reactants 2) Then by calculating the total energy released by making all the bonds in the products 3) Then by calculating the difference between the two totals |
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What are two ways in which hydrogen can be used as a fuel? |
in combustion engines, or in fuels cells |
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Most group __ and __ metal ions can be identified using ________ tests |
1, 2, flame |
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What colour does lithium burn in? |
Red |
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All ________ ions are positive |
Metal |
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Some positive ions can be identified by using _____________ ___________ solution |
Sodium hydroxide |
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What happens when sodium hydroxide is added to a solution of metal hydroxide? |
A precipitate of the metal hydroxide forms |
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What metal ions form a white precipitate in a sodium hydroxide test? |
Aluminium, calcium and magnesium |
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Iron hydroxide is either the colour __________ or __________ . |
Green or brown |
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What are three negative ions? |
Carbonate ions, Halide ions, and sulfate ions |
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How can we test for carbonate ions? |
Adding the substance to dilute hydrochloric acid, to see if it fizzes. If the gas produced turns limewater cloudy, carbonate ions are present.
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How can we test for halide ions?
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By adding dilute nitric acid and silver nitrate solution to form a precipitate |
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In a test for halide ions, what ions give what colours? |
Chloride ions give a white precipitate Bromide ions give a cream precipitate Iodide ions give a yellow precipitate |
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How can we test for sulphate ions? |
By adding dilute hydrochloric acid and barium chloride solution. If a white precipitate forms, Sulfate ions are present |
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What is a tritration used for? |
Measuring how much acid and alkali react together fully |
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How is a titration carried out? |
An amount of alkali is measured out using a pipette and is put into a conical flask. an indicator is added to the alkali. A burette is filled with acid, which is then slowly added to the alkali. When the indicator changes colour the end point has been reached. |
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What is the end point of a neutralisation reaction? |
When the neutralisation reaction is complete |
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What is used to show the end point of a neutralisation reaction? |
An indicator |
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Concentrations of solutions can be measured in _______ or __________ . |
g/dm cubed or mol/dm cubed |
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How can concentration be calculated? |
1) Finding how much solute is in 1cm cubed of the solution 2) Finding how much solute is in 1dm cubed of the solution (this is the result in g/dm cubed) 3) Finding the Fr 4) Dividing the concentration in g/dm by the Fr (This gives the concentration in mol/dm cubed) |
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What is qualitative analysis? |
Analysing a sample to find out what substances are in it
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What is quantitative analysis?
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Analysing a sample to see how much of a substance is in it |
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The results of an analysis is often compared against existing ______________ to identify substances |
Databases |
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What is a reversible reaction? |
When the products of a reaction can react to reform the original reactants |
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What is a closed system? |
When no reactants or products can escape |
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What is equilibrium? |
When the forward and backward rates of a reversible reaction are the same |
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What happens to the amounts of products and reactants in equilibrium? |
They stay the same |
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Equilibrium requires a ____________ system |
Closed |
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Changing reaction conditions such as _______________ can change the amount of ___________ and reactants in a reaction at equilibrium |
Concentration |
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How does changing the temperature of a reversible reaction affect it? |
Increasing the temperature allows the endothermic reaction to produce more product, and vice versa for decreasing the temperature |
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How does changing the pressure of a reversible reaction affect it?
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Increasing the pressure allows the reaction which produces less molecules of gas to make more product, and vice versa for decreasing the pressure
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What is the Haber process? |
The process used to make ammonia |
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Ammonia is useful for making other chemicals such as... |
Fertilisers |
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Ammonium is made from ____________ and ____________ in the Haber process |
Nitrogen, Hydrogen |
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What conditions are nitrogen and hydrogen reacted under in the Haber process? |
450 C at 200 atm, with an iron catalyst |
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Why are these conditions used in the Haber process? |
They are the most economical - They produce a reasonable yield of ammonia at a reasonable rate |
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Any unreacted nitrogen and hydrogen are _____________ in the Haber process |
Recycled |
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In the Haber process, the products have fewer gas molecules than the reactants, so the amount of ammonia is increased by... |
Increasing the pressure |
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Why isn't the pressure in The Haber process 1000 atm? |
It would be to expensive to be economical |
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The forward reaction is exothermic in the Haber process, so the yield of ammonia can be increased by... |
Lowering the temperature |
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Why is the temperature of the Haber process not very low? |
Lowering the temperature decreases the reaction rate |
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Series of molecules that have a general formula are called... |
Homologous series |
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What are two examples of homologous series? |
Alkanes and alkenes |
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What is the functional group for alcohols? |
-O-H |
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The first three members of the homologous alcohol series are... |
Methanol, Ethanol and Propanol |
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What is the functional group for carboxylic acids? |
-COOH |
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What are the first three members of the carboxylic acid homologous series? |
Methanoic acid, ethanoic acid, and propanoic acid |
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What does each member of every homologous series start with? |
Meth, eth and prop |
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What is the functional group of esters? |
-COO- |
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What is the structural formula of this ester, and what is it called? |
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Alcohols are used as two things - what are they? |
Solvents and fuels |
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What is the main alcohol in alcoholic drinks? |
Ethanol |
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What is produced when alcohols burn? |
CO2 and water |
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Alcohols are volatile - What does this mean? |
They evaporate easily |
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Sodium reacts with alcohol to produce _____________ gas |
Hydrogen |
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Ethanol can be oxidised to ethanoic acid in two ways - What are they? |
By using chemical oxidising agents (e.g. Potassium dichromate) or by the actions of microbes |
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Ethanoic acid is what makes __________ sour |
Vinegar |
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Solutions of carboxylic acids have a ph of _______ ________ 7. |
Less than |
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How are esters made? |
By reacting a carboxylic acid and an alcohol, with a catalyst |
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What is used as a catalyst in a reaction to make an ester? |
An acid |
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Why are carboxylic acids different to other acids? |
It reacts with an alcohol to produce an ester, in the presence of an acid catalyst |
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Esters are ____________ compounds |
Volatile |
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Why are some esters used as flavourings? |
They have strong smells and tastes |
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How can you tell if a solution is acidic? |
if it fizzes when added to a carbonate |
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What are two problems with using large amounts of land to grow biofuel crops? |
The land could have been used to grow food, and it may increase deforestation |
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What four thing have to be labelled in an energy level diagram? |
Reactants, products, activation energy and energy change |
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Where is nitrogen and hydrogen obtained from for the Haber process? |
The air, and Natural gas, respectively |
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What colour does sodium burn in a flame test? |
Yellow |
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What colour does potassium burn in a flame test?
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Lilac |
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What colour does calcium and lithium burn in a flame test?
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Red |
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What colour doe barium burn in a flame test? |
Green |
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In a test for Halide ions, chlorine ions give a _____________ precipitate |
White |
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In a test for Halide ions, bromide ions give a _____________ precipitate
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Cream |
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In a test for Halide ions, iodide ions give a _____________ precipitate
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Yellow |
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In a test using sodium hydroxide solution, what metals give a white precipitate? |
Aluminium, calcium and magnesium |
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In a test using sodium hydroxide solution, what metal gives a blue precipitate?
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Copper |
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In a test using sodium hydroxide solution, what metal gives a green precipitate?
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Iron (II) |
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In a test using sodium hydroxide solution, what metal gives a brown precipitate?
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Iron (III) |
