Section 2: Chemistry of the Elements Flashcards
Define isomer
Two or more compounds with the same molecular formula but a different structural formula
Name 3 indicators
Phenolphthalein, metyl orange, universal indicator
What groups of the periodic table are the following in:
The halogens
The alkali metals
The noble gases
halogens - 7
alkali metals - 1
noble gases - 8/0
What is a group and period in the periodic table
A column is a group and a row is a period
What pH are the oxides of metals and non-metals?
Metal oxides are usually alkaline, non-metal oxides are usually acidic
Why do elements in the same group have similar chemical properties?
They have the same number of electrons on the outer shell
Why are the noble gases unreactive?
They have a full outer shell
Why are the group 1 metals so reactive?
They only have 1 electron in the outer shell. It is easy to lose this one electron so they are reactive
What are the word and balanced symbol equations for the reactions of the three group 1 metals with water?
lithium + water –>lithium hydroxide and hydrogen
2 Li(s) + 2 H20(l) –>2 LiOH (aq) + H2(g)
sodium + water –> sodium hydroxide and hydrogen
2 Na(s) + 2 H20(l) –>2 NaOH (aq) + H2(g)
potassium + water –>potassium hydroxide and hydrogen
2 K(s) + 2 H20(l) –>2 KOH (aq) + H2(g)
Observations for lithium reacting with water
3 things
Lithium floats, effervesence,dissolves as it reacts
Observations for sodium reacting with water (4 things)
Sodium melts into ball, moves around surface of water, effervesence, burns orange flame until it disappears
Observations for potassium reacting with water (5 things)
potassium melts into ball, floats around surface of water, ignites instantly, lilac flame with sparks, sometimes small explosion before it disappears
What is thetrend in reactivity of Group 1? Why?
As you go down the group, the elements become more reactive. This is because there more shells of electrons and the outer electron is further from the nucleus, the attraction between electron and nucleus is then weaker and therefore easier to lose
What is the charge on a group 1 ion? Why?
Group 1 metals lose 1 electron so form an ion with a single positive charge
What are the Electronic configurations of lithium, sodium and potassiumas a regular element and ion
Li Normal: 2.1 Ion: 2
Na Normal: 2.8.1 Ion: 2.8
K Normal: 2.8.8.1 Ion: 2.8.8
Give equations to show how lithium, sodium and potassium become ions?
Li –> Li+ + e-
Na –> Na+ + e-
K –> k+ + e-
The harder it is to extract the more/less reactive the metal is
more
A metal that is oxidised in a reaction is called the ______ agent?
Reducing
What is another name for iron (III) oxide?
What conditions does iron rust in? (two things)
How can rusting be prevented?
(4 things)
Rust.
When it is in contact with oxygen and water
Galvanising, painting, coating, oiling
What type of reaction is when the more reactive metal takes a least reactive metals place in a compound?
A chemical reaction in which a compound is broken down into two or more smaller substances?
What is a redox reaction?
Displacement
Decompositon
A reaction where both reduction and oxidation take place
General Equation for reacting a metal with an acid is?
Acid+Metal—>Salt+Hydrogen
Which metal is more reactive? Lithium, Copper, or Zinc?
Lithium
What are reactants in the thermite reaction?
Aluminium and iron oxide
Why does aluminium not corrode as quickly as steel and iron?
It has a protective oxide layer
Which metal is often used for sacrifical protection of iron?
Magnesium
What gases are present in air? (4 main ones) and give their percentages
Nitrogen, Oxygen, Argon and Carbon Dioxide.
78% N2, 21% O2, 0.9% Ar and 0.03% CO2.
How canexperiments involving the reactions of elements be used to investigate the percentage by volume of oxygen in air?
Copper, iron and phosphorus all react with the oxygen in air. If you know the volume of air that you have, then react it with on of these, then re measure the volume of air; what has been lost is all oxygen that reacted.
What environmental issue is associated with carbon dioxide?
Greenhouse effect and global warming.
Describe the solubility and density of carbon dioxide.
Denser than air, soluble in water at high pressure.
What is produced when calcium carbonate is heated strongly?
Calcium oxide and carbon dioxide.
Which word best describes magnesium oxide?
acid, neutral, alkali, base
Base
Describe the reaction of magnesium with oxygen.
Burns very brightly and at a very high temperature. Magnesium metal turns into a white powder
What observations could be made from burning sulfur?
Strong blue flame, poisonous and colorless gas is produced.
Name the products of each of these reactions Hydrochloric acid + Magnesium ->
Hydrochloric acid + Aluminium ->
Hydrochloric acid + Zinc ->
Hydrochloric acid + Iron ->
Magnesium Chloride +Hydrogen
Aluminium Chloride + Hydrogen
Zinc Chloride + Hydrogen
Iron Chloride + Hydrogen
Name the products of each of these reactions Sulfuric Acid +Magnesium -> Sulfuric Acid +Aluminium -> Sulfuric Acid +Zinc -> Sulfuric Acid +Iron ->
Magnesium Sulfate + Hydrogen
Aluminium Sulfate + Hydrogen
Zinc Sulfate + Hydrogen
Sulfuric Acid + Hydrogen
Are Acid + Metal reactions endothermic or exothermic?
Exothermic
Hydrogen + Oxygen ->
Water
Is combustion of hydrogen exothermic or endothermic?
Highly Exothermic
What is the colour of Anhydrous copper sulphate and hydrated copper sulphate?
White and then blue
Describe a physical test to show whether water is pure.
If water boiled/evaporated, container is left clean, and the water boils at 100oC
Describe the exothermic / endothermic nature of the reversible reaction of copper sulphate and water
In the forward direction (water and anhydrous copper sulphate reacting) it is exothermic and in the backward direction (decomposition of the hydrated copper sulphate) it is endothermic
What are the similar properties of the transition metals? (6 things)
They are strong with high melting points, yet are malleable, ductile and sometimes lustrous. They all conduct electricity.
How many electron shells are present in caesium?
There are six.
Describe the following elements at room temperature
chlorine
bromine
iodine
chlorine - A greenish-yellow gas.
bromine - A red-brown liquid.
iodine - Solid, shiny, purple crystals.
List the Group 7 elements in order of reactivity.
Flourine, Chlorine, Bromine, Iodine, Astatine
What happens when a more reactive halogen reacts with a compound containing a less reactive halogen?
The less reactive halogen is displaced.
Describe a flame test and identify the colours the following would make a flame: lithium sodium potassium calcium
dip a clean flame test loop in the sample solution, hold the flame test loop at the edge of a bunsen burner flame, wash with acid in between test lithium - red sodium - yellow-orange copper - blue-green potassium - lilac calcium - orange-red
How do you test for the following gases: chlorine ammonia carbon dioxide oxygen hydrogen
chlorine - Turns litmus paper red before bleaching it
ammonia - damp red litmus paper should turn blue if ammonia is present
carbon dioxide - limewater test- should turn milky
oxygen - relights a glowing splint
hydrogen - squeaky pop test
Sodium hydroxide will produce what colour precipitate with the following ions
Fe2+
Fe3+
Cu2+
NH4+ (ammonium)
Fe2+ green, turns orange/brown over time
Fe3+ orange/brown
Cu2+ pale blue
NH4+ (ammonium) put red litmus paper at the end of the test tube and it should turn blue (gently heat tube sometimes required)
How do you test for Halide’s?
The test solution is acidified using a few drops of dilute nitric acid, and then a few drops of silver nitrate solution are added.
White = chlorine
cream = bromine
yellow = iodine
How do you test for the following ions:
carbonate ion (CO32-)
sulphate ion (SO42-)
React with acid, there will be effervescence which is carbon dioxide.
The test solution is acidified using a few drops of dilute hydrochloric acid, and then a few drops of barium chloride solution are added. A white precipitate of barium sulfate forms if sulfate ions are present.
Describe the trend in the reactivity of the Group 7 elements
The Group 7 elements become more reactive as you go up the group. This is because there are less shells of electrons, so an electron that will be gained is closer to the nucleus. The means that attraction between the nucleus and electron is greater and so the electron is more easily gained.
What is the difference in mining unreactive and reactive elements?
Unreactive elements (gold, silver) can be mined as the element, whereas reactive elements will have formed compounds (iron oxide) which need to be mined and then the metal extracted from the compound.
What are the pH’s of the following types of substances:
Acids
Neutral
Alkalis
Acids - pH 1-6. Neutral - pH 7. Alkali - pH 8-14
Give the colours of the indicators litmus, phenolphthalein, universal indicator and methyl orange in acid and alkaline solutions
Litmus - Acid = red, alkali = blue.
Phenolphthalein - acid = colourless, alkali - pink.
Universal Indicator - strong acid = red, strong alkali = purple
Methyl orange - acid = red, alkali = yellow
What are the ions that make a substance acidic or alkaline?
H+ = acidic. OH- = alkaline
Complete the following general equations: Metal + Acid -> Metal oxide (base) + acid-> Metal hydroxide (alkali) + acid -> Metal carbonate + acid ->
Metal + Acid -> Salt + Hydrogen
Metal oxide (base) + acid-> Salt + Water
Metal hydroxide (alkali) + acid -> Salt + Water
Metal carbonate + acid -> Salt + Water + Carbon Dioxide
What are the rules for solubility of salts? (sodium, potassium, ammonium, nitrates, chlorides, sulphates, carbonates
Sodium, potassium ammonium, nitrates - all soluble.
chlorides - all except silver
sulphates - soluble except barium and calcium
carbonates - insolube except sodium, potassium and ammonium.
Describe an experiment to form a soluble salt from an acid and an alkali
Carry out a titration using indicator to determine the exact amount of alkali needed to neutralise the acid. Repeat the process without indicator using exactly the same volume of alkali. Evaporate the water from the mixture to leave the salt behind
Describe an experiment to form a soluble salt from an acid and a base
React a solution of the acid with base. Once you add base and it does not dissolve as it reacts then all of the acid must have reacted. Filter the mixture to remove excess base and then evaporate the wate to leave just the salt
Descirbe an experiment to form an insoluble salt using a precicpitation reaction
For example silver choldride is an insoluble salt- to form you need a soluble silver salt and a soluble chloride salt. Silver nitrate and sodium chloride are both soluble salts and when combinded form soluble sodium nitrate and insoluble silver chloride.The silver chloride forms as tiny particles in the mixture- forms a precipitate. The precicpitate can be washed, rinsed with water and left to dry on the filter paper.
Describe how to carry out a titration
Use a pipette and add 25cm^3 of alkali to a clean conical flask. Add indicator to the akali solution and place on a white tile, which allows for colour to be easily seen. Fill the burette with acid and note the starting volume. Slowly add the acid to the alkali while swirling the mixture. Stop adding the acid when the end point is reached (final colour is achieved) and record the volume left on the burette. To calculate how much acid was used take the final volume from the starting volume. Continue to repeat the steps till your readings are consistent.
How is the method of extracting a metal determined?
Metals below carbon in the reactivity series can be extracted by reduction with carbon (Zinc, iron, tin, lead).
Metals above carbon have to be extracted by electrolysis
Describe the process of extracting via reduction
The metal oxide is heated in the presence of carbon or carbon monoxide to be reduced to the pure metal
Give one particular property of aluminium and iron and suggest a use for it based on that property
Aluminium has a low density and is used for aircraft. Iron has a high tensile strength so is used for buildings
Describe the corrosion resistance of iron and aluminium
Iron corrodes easily (and is called rust) when it comes into contact with water and oxygen, and this layer is brittle.
Aluminium forms a more solid oxide layer on its surface which prevents further corrosion
What are the raw materials in the Haber Process, and how are they obtained?
nitrogen from air and hydrogen from reactions of natural gas with steam
What are the conditions for the Haber Process (T, P and cat?)
Temperature - 450oC. Pressure - 200 atm. Catalyst - Fe
How is ammonia separated from the products?
The reaction mixture is cooled and ammonia condenses. Nitrogen and hydrogen have lower boiling points so remain as gases.
What are the uses of ammonia? (3)
fertilisers,nitric acid and cleaning products
Explain the temperature of the Haber Process
The temperature of 450oC is high to inncrease the rate of the reaction but not so hugh that it reduces the yield too much. It is a compromise
Explain the pressure of the Haber Process
The pressure of 200 atm is high to increase rate and yield but not so high as it is very expensive and can be dangerous
What is the equation for the Haber Process?
N2 + 3 H2 ⇌ 2 NH3
Describe the electrolysis of sodium chloride solution, including its products and the uses for each product.
Concentrated sodium chloride is electrolysed in a diaphragm cell to produce hydrogen (fuel, chemical synthesis), chlorine (bleach, disinfectant) and sodium hydroxide (soap)
