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| What is an ion, how do Non-metals/Metals become ions? | 1) Ion - an atom/group of atoms with a positive or negative charge (form when atoms lose or gain electrons to obtain a full outer shell) 2) metal atoms - lose electrons (to form positively charged ions) 3) non-metal atoms - gain electrons (to form negatively charged ion) |
| Do ionic compounds have high/low melt/boiling points, why? | - they have high melt/boiling points - due to strong electrostatic forces of attraction between oppositely charged ions - as the ionic lattice contains so many ions, lots of energy is needed to overcome the ionic bonding ∴ they have high melt/boiling points |
| Do ionic compounds conduct electricity, why? | - Only is liquid form (melted or dissolved in water to form an aqueous solution) - because the particles are both: charged and free to move (in liquid form) |
| How is a covalent bond formed? | When 2 (non-metal) atoms share a pair of electrons from their outer shells |
| What is the typical size of a small molecule? | 0.1 nm OR 1 × 10^-10 m |
| Do small molecules have low/high melt/boiling points, Why? | - Most have low melt/boiling points - The intermolecular forces are much weaker than the covalent bonds - ∴ relatively small amounts of energy is needed to break these intermolecular bonds - The bigger the molecule, the stronger the intermolecular forces, the higher the melt/boiling points |
| Do small molecules conduct electricity? | - No - substances must contain charged particles (& be free to move from place to place) - but small molecules have no overall electric charge (the forces cancel each other out) |
| Do giant covalent bonds have high/low melt/boiling points, Why? | - High - large amounts of energy are needed to overcome their strong covalent bonds to make them melt or boil |
| Do giant covalent bonds conduct electricity, Why? | - Most do not (graphite does) - most substances with giant covalent structures have no charged particles that are free to move |
| State the Structure/Bonding & Properties of Diamond. | STRUCTURE/BONDING: - each carbon joined to 4 others by strong covalent bonds - the carbon atoms form a regular tetrahedral network structure - no free electrons PROPERTIES: - hard, due to the network of carbons held together by strong covalent bonds - this makes it useful for cutting tools like oil rig drills - high melting point, doesn't conduct electricity |
| State the Structure/Bonding & Properties of Graphite. | STRUCTURE/BONDING: - each carbon joined to 3 others - the carbon atoms form layers of hexagonal rings - no covalent bonds between the layers - there's 1 delocalised electron from each atom PROPERTIES: - conducts electricity (has delocalised electrons) - slippery, due to weak forces between layers - they can slide over each other |
| State the Structure/Bonding & Properties of Graphene. | STRUCTURE/BONDING: - 1 atom thick, It's a single layer of graphite (refer to the previous flash card) PROPERTIES: - high melting point (due to strong covalent bonds) - very strong - conducts electricity, due to the delocalised electrons that are free to move |
| What is a Fullerene, what is Buckminster fullerene? | - Molecules of carbon with hollow shapes, their structures are based of hexagonal rings (however sometimes they have 5 or 7 rings) of carbon - Buckminster fullerene - sphere containing 60 carbons, arranged in hexagonal rings (6 carbons on each ring) |
| What are some uses of Fullerenes? | - Deliver pharmaceutical drugs - lubricants (stop grinding) - catalysts (speed up chemical reactions) - (nanotubes:) tennis rackets - for reinforcement |
| What are carbon nanotubes, give Properties? | - Carbon nanotubes are cylinders of fullerenes PROPERTIES: - high tensile strength (stretched without breaking) - good heat & electricity conductors - high surface area : volume ratio |
| What are Polymers & what are their properties? | - Polymers have very large molecules joined together by strong covalent bonds PROPERTIES: - Strong intermolecular forces - therefore, high melt/boiling points |
| State the Structure/Bonding & Properties of Metals. | STRUCTURE/BONDING - outer shell electrons are delocalised, ∴ free to move through the whole structure PROPERTIES: - conduct electricity - their delocalised electrons carry electrical charge through the metal - good conductors of thermal energy - their delocalised electrons transfer energy - have high melt/boiling points - the metallic bonding in the giant structure of a metal is very strong - large amounts of energy are needed to overcome the metallic bonds in melting and boiling - Can be bent/shaped - the layers can slide over each other |
| Why are Alloys sometimes more useful than pure metals? | - they are harder, it's more difficult to bend them - this is because alloys are made up of different metals with atoms of different sizes - this distorts the layers ∴ it's harder for them to slide over each other |
| How is a covalent bond formed? | When 2 (non-metal) atoms share a pair of electrons from their outer shells |
| What is the typical size of a small molecule? | 0.1 nm OR 1 × 10^-10 m |
| Do small molecules have low/high melt/boiling points, Why? | - Most have low melt/boiling points - The intermolecular forces are much weaker than the covalent bonds - ∴ relatively small amounts of energy is needed to break these intermolecular bonds - The bigger the molecule, the stronger the intermolecular forces, the higher the melt/boiling points |
| Do small molecules conduct electricity? | - No - substances must contain charged particles (& be free to move from place to place) - but small molecules have no overall electric charge (the forces cancel each other out) |
| Do giant covalent bonds have high/low melt/boiling points, Why? | - High - large amounts of energy are needed to overcome their strong covalent bonds to make them melt or boil |
| Do giant covalent bonds conduct electricity, Why? | - Most do not (graphite does) - most substances with giant covalent structures have no charged particles that are free to move |
| State the Structure/Bonding & Properties of Diamond. | STRUCTURE/BONDING: - each carbon joined to 4 others by strong covalent bonds - the carbon atoms form a regular tetrahedral network structure - no free electrons PROPERTIES: - hard, due to the network of carbons held together by strong covalent bonds - this makes it useful for cutting tools like oil rig drills - high melting point, doesn't conduct electricity |
| State the Structure/Bonding & Properties of Graphite. | STRUCTURE/BONDING: - each carbon joined to 3 others - the carbon atoms form layers of hexagonal rings - no covalent bonds between the layers - there's 1 delocalised electron from each atom PROPERTIES: - conducts electricity (has delocalised electrons) - slippery, due to weak forces between layers - they can slide over each other |
| State the Structure/Bonding & Properties of Graphene. | STRUCTURE/BONDING: - 1 atom thick, It's a single layer of graphite (refer to the previous flash card) PROPERTIES: - high melting point (due to strong covalent bonds) - very strong - conducts electricity, due to the delocalised electrons that are free to move |
| What is a Fullerene, what is Buckminster fullerene? | - Molecules of carbon with hollow shapes, their structures are based of hexagonal rings (however sometimes they have 5 or 7 rings) of carbon - Buckminster fullerene - sphere containing 60 carbons, arranged in hexagonal rings (6 carbons on each ring) |
| What are some uses of Fullerenes? | - Deliver pharmaceutical drugs - lubricants (stop grinding) - catalysts (speed up chemical reactions) - (nanotubes:) tennis rackets - for reinforcement |
| What are carbon nanotubes, give Properties? | - Carbon nanotubes are cylinders of fullerenes PROPERTIES: - high tensile strength (stretched without breaking) - good heat & electricity conductors |
| What are Polymers & what are their properties? | - Polymers have very large molecules joined together by strong covalent bonds PROPERTIES: - Strong intermolecular forces - therefore, high melt/boiling points |
| State the Structure/Bonding & Properties of Diamond. | STRUCTURE/BONDING - outer shell electrons are delocalised, ∴ free to move through the whole structure PROPERTIES: - conduct electricity - their delocalised electrons carry electrical charge through the metal - good conductors of thermal energy - their delocalised electrons transfer energy - have high melt/boiling points - the metallic bonding in the giant structure of a metal is very strong - large amounts of energy are needed to overcome the metallic bonds in melting and boiling - Can be bent/shaped - the layers can slide over each other |
| Why are Alloys sometimes more useful than pure metals? | - they are harder, it's more difficult to bend them - this is because alloys are made up of different metals with atoms of different sizes - this distorts the layers ∴ it's harder for them to slide over each other |
| What happens when a metal reacts with oxygen? | - Metal + Oxygen -> Metal Oxide (EG: magnesium + oxygen -> magnesium oxide) - an oxidation reaction takes place |
| What happens when you seperate a metal from oxygen? | - a reduction reaction takes place (in a displacement reaction, one metal is oxidised, the other is displaced) |
| How do magnesium and iron react with oxygen? | Magnesium - vigorously, great deal of heat and light is released iron - slowly, taking weeks or months |
| What's the word equation for the reaction between metals & water? | Metal + water -> metal hydroxide + hydrogen (EG: potassium + water -> potassium hydroxide + water) |
| What determines how rapidly an element reacts? | It's ability to lose an electron and form a positive ion (table shows reactivity of metals [doesn't need to be memorized]) |
| What happens to metals when they are displaced? | - A more reactive metal displaces a less reactive metal - One metal is oxidised (gains oxygen) - The other is reduced (loses oxygen) (EG: carbon + copper oxide -> carbon dioxide + copper) |
| What happens during oxidation and reduction (in terms of electrons)? | OIL - Oxidation Is Loss (EG: Al -> Al^(3+) + 3e^-) RIG - Reduction Is Gain (EG: O +2e^- -> O^(2-)) |
| Give the symbol equations for the 3 most popular acids. | Hydrochloric acid - HCl Sulfuric acid - H2SO4 Nitric acid - HNO3 |
| What do acids produce in aqueous solutions? | H+ ions (EG: HNO3 -> H^(+) + NO3^-) |
| What are bases? | - Chemicals which can neutralise acids, producing a salt + water - Usually metal oxides OR metal hydroxides - If they are insoluble in water (EG: copper oxide), they are just bases - If they are soluble in water (EG: sodium hydroxide), they are both bases & alkalis |
| What happens in this reaction in terms of electrons: hydrochloric acid + magnesium -> magnesium chloride + hydrogen (include the half equations)? | OXIDATION: Mg -> Mg^(2+) +2e^- REDUCTION: 2H^(+) + 2e^(-) -> H^2 |
| How can we identify the rate of reactions using oxidation & reduction reactions that occurs when metals react with dilute acids? | The more easily an elements forms ions, the quicker rate of reaction, EG: - Magnesium reacts rapidly with dilute acid -> easily forms the ion Mg^2+ - Zinc reacts quite rapidly with dilute acid -> quite easily forms the ion Zn^2+ - Iron reacts slowly with dilute acids -> less easily forms Fe^2+ |
| What ions do salts contain and where do those ions come from? | - positive ions which come from the base/alkali - negative ions which come from the acid |
| What do the 3 main acids form (as salts)? | Hydrochloric acid -> ... chlorides sulfuric acid -> ... sulfates nitric acid -> ... nitrates |
| What happens when we react an acid with a base/alkali? | We make a SALT + WATER EG: sulfuric acid + zinc oxide -> zinc sulfate + water |
| How do metal carbonates react with a acids? | They make a SALT + WATER + CARBON DIOXIDE EG: - hydrochloric acid + sodium carbonate -> sodium chloride + water + carbon dioxide - hydrochloric acid + calcium carbonate -> calcium chloride + water + carbon dioxide - hydrochloric acid + potassium carbonate -> potassium chloride + water + carbon dioxide |
| These flashcards are in metals and reactivity lol | These flashcards are in metals and reactivity lol |
| What is the formula for percentage atom economy? | Atom economy = (total Mr of desired product/total Mr of all reactants) x 100 |
| Why can ionic compounds conduct electricity when molten/dissolved in water? | The forces of attraction are broken and the ions are free to move and conduct electricity - these are electrolytes |
| What happens during electrolysis in terms of electrons | 1) Positive ions attracted to (negative) cathode, gaining electrons and forming atoms - reduction 2) Negative ions attracted to (positive) anode, losing electrons and forming atoms - oxidation |
| Explain the process of extracting aluminium using electrolysis. | 1) Mixed with cryolite - lowers melting point reducing amount of energy needed and saving money 2) Apply an electric current to the molten aluminium oxide - ions free to move 3) Cath/anode are made of graphite - a form of carbon which is a very good conductor of electricity and has a very high melting point and can therefore be used at high temps 4) Reduction: Al3+ attracted to (-) cathode gaining 3 electrons forming an atom: Al3^(+) + 3e^(-) -> Al 5) Oxidation: 2^(-) attracted to (+) anode losing 2 electrons forming an atom: O2^(-) -> O + 2e^(-) |
| What's the definition of electrolysis? | Electrolysis is the process by which ionic substances are decomposed (broken down) into simpler substances when an electric current is passed through them. Electricity is the flow of electrons or ions |
| Why must the anodes be replaced regularly during electrolysis? | They are made of carbon, the oxygen molecules produced at the anode react with the graphite (carbon), forming carbon dioxide gas |
| Why's electrolysis expensive? | - Melting the compounds such as aluminium oxide requires a great deal of energy - A lot of energy is required to produce an electric current |
| What additional factor must we consider for electrolysis of aqueous solutions compared to electrolysis of molten compounds? | - Water is also involved - water ionises (splits) & could therefore possibly move to the electrodes - Hydrogen (H+) is produced at the cathode if the other '+' charged ion is more reactive than hydrogen (refer to the image below) |
| What's usually produced at the anode during electrolysis of aqueous solutions & what is the exception? | - Oxygen - The exception: if the aqueous solution contains halide ions (Group 7) than the halogen will be produced at the anode |
| Explain the required practical: Electrolysis of aqueous solutions - Copper (II) Chloride | 1) Pour 50cm3 of copper (II) chloride solution into beaker 2) Place plastic petri dish (with 2 holes) over beaker and place each graphite rod into each hole - electrodes (carbon graphite is unreactive so the electrodes are inert - wont react). Make sure the electrodes don't touch each other - else it'll cause a short circuit 3) Attach crocodile clips to the rods and connect the rods to the terminals of low-voltage power supply, select 4V on the power supply and switch it on 4) The (-) cathode will become coated in copper, copper's less reactive than hydrogen and will therefore be discharged at the cathode 5) At the anode, bubbles of gas will also be produced and you may smell chlorine in the air, chlorine is a halide ion and will therefore be discharged at the anode 6) Placing a damp blue litmus paper near the anode and it becomes bleached proves chlorine is present |
| Explain the required practical: Electrolysis of aqueous solutions - Sodium Chloride | 1) Pour 50cm3 of sodium chloride solution into beaker 2) Turn on low voltage power supply 3) Anode: bubbles of gas produced which bleach damp blue litmus paper - chlorine, because chlorine is a halide ion, it is discharged at the anode 4) Cathode: bubbles of gas produced - hydrogen, hydrogen is discharged at the cathode as it is less reactive than sodium 5) We can prove hydrogen is produced at the cathode by collecting it then testing it with a lit splint, it'll produce a squeaky pop |
| Describe the history of the atom. | 1)19th century - John Dalton - solid spheres 2)1897 - JJ Thomson - plum pudding - Experiments of charge and mass showed a positively charged ball with electrons embedded - plum pudding 3)1909 - Ernest Rutherford - Alpha particle - Positive alpha particles fired at thin sheet of gold - expected to pass through or slight deflection - most went through but some were deflected more than expected, some backwards - came up with nuclear model - concentrated positive nucleus with cloud of electrons, mostly empty space 4)Scientists realised a cloud of electrons would collapse - Niels Bohr nuclear model meant electrons were in shells at a fixed orbit 5)Rutherford and others conducted nucleus had smaller particles which had same charge as a hydrogen nucleus - protons 6)James Chadwick conducted experiments showing evidence for neutrons . |
| How many moles of copper will be produced if we used 0.5 moles of copper sulphate and 1 mole of magnesium? Calculate the mass of copper produced. Ar Cu = 63.5 Ar S = 32 Ar O = 16 Ar Mg = 24 CuSO4 + Mg -> MgSO4 + Cu | CuSO4 + Mg -> MgSO4 + Cu 1) We only have 0.5 moles of copper sulphate so its the limiting reactant 2) If there is only 0.5 moles of copper then there will only be 0.5 moles of copper 3) To work out mass: mass = moles x Ar (relative atomic mass) - so 0.5 x 63.5 = 31.75g |
| What is the overall charge of an ionic compound? | (0 the charges always cancel out) |
| State the formula for sodium oxide. sodium = Na+ Oxygen = O2- | Na2O You need 2 sodium to cancel out the 2- from oxygen |
| State the formula for calcium hydroxide. Calcium = Ca2+ Hydroxide = OH- | Ca(OH)2 2 hydroxides are required to cancel out the 2+ charge |
| What is an exothermic reaction? | 1)When energy is given out to the surroundings. Surroundings have more energy than they started with so temp increases. 2)More heat energy is released in making bonds in products than taken when breaking bonds in reactants |
| What is an endothermic reaction? | 1)When energy is taken in from the surroundings. The temperature of surroundings decreases 2)Less heat energy is released in making bonds in products than taken when breaking bonds in reactants |
| Give the required practical for temperature change. | 1)Place polystyrene cup in glass beaker to make it more stable. 2)Measure an appropriate volume of each liquid, eg 25 cm3. 3)Place one of the liquids in a polystyrene cup. 4)Record the temp of the solution 5)Add the second solution and record highest or lowest temp obtained 6)Change your independent variable and repeat the experiment. (Your independent variable could be the concentration of one of the reactants, or the type of acid/alkali being used, or the type of metal/metal carbonate being used.) |
| State weather this reaction is exothermic or endothermic (view pic) | Exothermic, overall change is negative, products have less energy than reactants |
| State weather this reaction is exothermic or endothermic (view pic) | Endothermic, overall change is positive, products have more energy than reactants |
| Hydrogen reacts with oxygen to form water: 2 × (H−H) + O=O → 2 × (H-O-H) Use the bond energies in the table to calculate the energy change for this reaction. Bond Bond energy H−H 436 kJ mol-1 O=O 498 kJ mol-1 O-H 464 kJ mol-1 | Energy in = (2 x 436) + 498 = 1370 kJ mol -1 Energy out = 2 × 2 × 464 = 1856 kJ mol-1 Energy change = in - out = 1370 - 1856 = -486 kJ mol-1 |
| How does a fuel cell work? | Hydrogen oxidies producing electric current. |
| Give the half equation for the reactions in a fuel cell | Cathode: 2H2 -> 4H+ + 4e- Anode: O2+ 4H+ + 4e- -> 2H2O |
| Compare hydrogen fuel cells and rechargable batteries. | Hydrogen fuel cells: Advantages: -produce electricity as long hydrogen is present -do not get less efficient -source of pure water Disadvantages: -hydrogen is explosive and difficult to store -produce low pd compared to rechargable so many are needed |
| Explain the physical properties of group one metals | - They are soft - Have relatively low melting points - Have relatively low densities |
| How do group 1 metals react with oxygen/chlorine? | - React rapidly with oxygen/chlorine- as we move down group 1 the elements react more rapidly |
| Why are group 1 metals more reactive as we move down it? | - When we move down group 1, the outer electron is less attracted to the nucleus and easier to lose - Because there's a greater distance between the positive nucleus and the negative outer electron - Secondly, the outer electron is shielded from the nucleus by the internal energy levels |
| Why are group 7 elements in pairs (O2, F2...)? | They have 7 electrons on their outer shells, so they covalently bond in pairs forming molecules - no overall charge |
| How do halogens produce non-metal compounds? | By bonding covalently with other non-metals |
| How are ionic compounds formed? | Group 7 elements, reacting with metals |
| What happens to the reactivity of Group 7 elements as you move down and why? | - Elements get less reactive as we move down Group 7 - Because as you move down, the elements have a greater distance between the outer energy level and the nucleus - As you move down the outer energy levels become more shielded from the + charge of the nucleus by the internal electrons - These factors reduce the attraction between the outer electrons and the nucleus, making it harder to attract an electron into its outer energy level |
| Explain how a Group 7 element can displace another | A more reactive halogen can displace a less reactive one from an aqueous solution of its salts EG: Potassium iodide (aq) + chlorine -> potassium chloride + iodine - here chlorine displaces iodine as it is more reactive |
| What is Avogadros constant? | The amount of particles in one mole of a substance: 6.02 x 10^23 |
| Calculate the number of water molecules in 0.5mol of water. | Number of water molecules = Avogadro's constant x amount of substance in mol 0.5 x 6.02 x 10^23 = 3.02 x 10^23 |
| Calculate the mass of 0.25 moles carbon dioxide CO2=44 | Mass = rfm x amount (moles) Mass = 44 x 0.25 Mass = 11g |
| Calculate the mass of 0.25 moles carbon dioxide CO2=44 | Mass = rfm x moles Mass = 44 x 0.25 Mass = 11g |
| What mass of nitrogen (N2) is needed to make 120g of nitrogen monoxide (NO). Mr NO = 30 Mr N2 = 28 N2 + 02 -> 2NO | Amount(mol) = mass / rfm amount = 120/30 amount = 4mol Ratio N2 : NO is 1:2 so 4 moles of NO makes 2 moles of N2 28 x 2 = 56 |
| 25cm^3 of HCl of concentration 1mol/dm3 reacts with 20cm NaOH. Calculate concentration of NaOH. | Convert to cm3 to dm3: HCl = 25/1000 = 0.025 NaOH = 20/1000 = 0.020 amount(mol) = concentration x volume 0.025 x 1 = 0.025 concentration = amount solute(mol)/amount NaOH(mol concentration = 0.025/0.020 concentration = 1.25 |
| Describe the Required Practical: Carrying out a Titration | 1. Use a pipette to transfer 25cm^3 of sodium hydroxide solution into a conical flask 2. Add 5 drops of indicator such as methyl orange to the alkali in the conical flask 3. Place conical flask on white tile to see colour change more clearly 4. Fill burette with sulfuric acid 5. Add acid to alkali until solution is neutral. Once colour change begins, add acid drop by drop until solution is neutral. Swirl solution to ensure acid and alkali mix 6. Read volume of acid from burette (from bottom of meniscus) |
| What's the equation to calculate no. of moles? | No. of moles = concentration × volume |
| How do you calculate the concentration of a substance in g/dm3 using its concentration in mol/dm3 | Multiply the mol/dm3 by the rfm |
| What ions do acids form when dissolved in water? | Acids form H+ ions when dissolved in water |
| What ions do alkalis form when dissolved in water? | Alkalis form OH- ions when dissolved in water |
| What's the difference between strong and weak acids in terms of ionisation? | Strong acids - fully ionise in aqueous solutions (hydrochloric, sulfuric and nitric acid) Weak acids - partly ionise in aqueous solutions (carbonic, ethanoic and citric acid), the reversible arrow (shown below) indicates a reversible reaction meaning only a fraction of the acid ionises |
| What happens when acids ionise? | They split, releasing H+ EG, HCl -> H^(+) + Cl^(-) |
| What is the difference between an alkali and a base? | Base - any substance that reacts with an acid forming a salt Alkali - any SOLUBLE substance that reacts with an acid forming a salt |
| Describe the relationship between the PH value of an acid and the concentration of hydrogen ions. | As the PH scale decreases by 1 unit, the concentration of hydrogen ions increases ×10 |