Chemistry topics starting with X, Y. and Z

School Science Lessons
Chemistry
2025-09-26
Chemistry, X, Y, Z
Chemistry, X
Chemistry, Y
Chemistry, Z

Chemistry, X
Contents
X-rays
Xanthoxylin
Xanthan gum
Xanthene dyes
Xanthodrol
Xanthone
Xanthophylls
Xanthoproteic test for proteins
Xanthotoxin
Xenon
Xylene
Xylenols
Xylose

Chemistry, Y
Contents
Yangambin
Yangonin
Yellow snowstorm reaction
Yoghurt
Yohimbine
Ytterbium
Yttrium
Yuanhuacine
Yunaconitine

Chemistry, Z
Contents
Zeaxanthin
Zenker's solution
Zeolite
Zephiran
Ziehl-Neelsen stain
Zinc
Zineb
Zingerone
Zingiberine
Ziploc bag
Zircon
Zirconia
Zirconium
Zirconium nitrate
Zizyphine
Zylon
Zylonite
Zymase
Zymase tests
Zytel

Xanthodrol
Xanthodrol, C13H10O2, (9-hydroxyxanthene), (9-xanthenol), urea tests, Toxic, flammable

Xanthoxylin, C10H12O4
Xanthoxylin, carboxylic ester, crystalline phenolic ketone, in fats and oils
Use to treat stomach spasms, fungus infections and pain.
It affects melanin content in the body.
It occurs in Sapium sebiferum, (Chinese tallow tree), in Zanthoxylum piperitum, (Japanese pepper tree).

Xanthan gum
Xanthan gum, E415, (from corn sugar fermentation), (vegetable gum)

Xenon, Xe
Xenon Table of Elements
Xenon, RSC
Atomic number: 54, Relative atomic mass: 131.29, RD 3.52(165 K), MP = -112 oC , BP = -108 oC ,
Specific heat capacity: 159 J kg-1 K-1
Commercial: Xenon Elements, Compounds
Xenon, Xe, (Greek xenos foreign, stranger), colourless, odourless, non-metal noble gas at room temperature and pressure, 0.00001% of the atmosphere.
Xenic acid, xenon trioxide solution, may not exist!
Specific heat capacity: 159 J kg-1 K-1.
Xenon occurs in lasers, fluorescent lamps.

Xylene, xylol, C8H10
Xylene [mixed isomers] is a colourless, sweet-smelling aromatic odour liquid that catches on fire easily, and floats on water.
It occurs naturally in petroleum and coal tar, and is produced from petroleum, and is toxic by ingestion.
Xylene is used as a solvent and in the printing, rubber, and leather industries..
It is also used as a cleaning agent, a thinner for paint, and in paints and varnishes, and in small amounts in airplane fuel and gasoline..
Xylenes are released into the atmosphere as fugitive emissions from industrial sources, from auto exhaust, and through volatilization from their use as solvents..
Inhalation exposure causes irritation of the eyes, nose, and throat, gastrointestinal effects, eye irritation, and central nervous system (CNS) effects..
Xylene cyanol FF, C25H27N2NaO6S2, acid blue 147, cyanol FF, histology dye, Toxic if ingested
Xylenes, ACS reagent, 98.5% xylenes + ethylbenzene basis, Xylene isomer mixture, CAS Number 1330-20-7
Xylol isomers:
* m-Xylol, m-xylene (1,3-Dimethylbenzene), Metaxylene, C8H10
* o-Xylol, o-xylene (1,2-Dimethylbenzene), Orthoxylene, C8H10
* p-Xylol, p-xylene (1,4-Dimethylbenzene), Paraxylene, C8H10
Low cost: from hardware stores and paint stores, as xylenes, (mixed dimethylbenzene isomers)
Xylene, curing agent for epoxy resin adhesives, surface coating, paint thinner, irritant, solvent for some marker pens and Canada balsam.
Xylol, oil-immersion microscopy clearing agent, removes immersion oil from objective, prepares embedded specimens and mounts.
Prepare carbol xylol solution: 3.7
Prepare DPX mountant: 6.2
Prepare xylene and methylbenzoate solution: 3.28
Clean microscope slides and coverslips: 2.5.1
Cleaning agents, solvents: 2.3.7, (See: 5.)

Xylenols, (CH3)2C6H3OH
Xylenols are volatile colourless solids, oily liquids, derivatives of phenol.
Xylenol orange, C31H32N2O13S, (metal indicator), Toxic if ingested, tetrasodium salt used for an indicator for metal titrations
Xylenol blue, C23H22O5S, p-Xylenolsulfonphthalein

Yangambin
Yangambin, C24H30O8, yangabin, furofuran lignan, peripheral vasodilation, antiallergic, anti-inflammatory.
It occurs in Rollinia species, Magnolia biondii, Virola elongata bark, Artemisia absinthium roots, Laurelia novae-zelandiae, and Tinospora sinensis
It is used as hallucinogenic snuff, arrow poison.

Yangonin
Yangonin, C15H14O4, (2-pyrone), aromatic ether, irritant, possible liver damage from use of kava in food.
It occurs in in kava, Piper methysticum root and Ranunculus silerifolius.
Kava, (Piper methysticum), kava kava

Ytterbium, Yb
Ytterbium, Table of the Elements
Ytterbium, RSC
Ytterbium, Yb, (Ytterby, Sweden), lanthanide, soft, silvery, malleable, in lasers
Ytterbium oxide, Yb2O3 in alloys, catalysts
Ytterbium (III) chloride hexahydrate, YbCl3.6H2O, animal food tracker

Yttrium, Y
Yttrium, Table of the Elements
Yttrium, RSC
Yttrium, Y, (Ytterby, Sweden), grey transition metal, protective oxide, red phosphorescence
Yttrium-90, reactor-produced medical radioisotope, half-life 64 hours, is used to treat liver cancer.
Yttrium, elements Y with Eu and Tb in TV screens (future shortfall), is used in microwave ferrites.
Yttrium (III) oxide, Y2O3, is used to make "1-2-3", super conductor, YBa2Cu3O7.

Zinc, Zn
Zinc Table of Elements
Zinc, RSC
Zinc, Zn (German zink zinc), hard, lustrous, blue-white metal that forms protective oxide layer in air preventing further oxidation.
Zinc is sold as zinc metal mossy, zinc dust (FLAM), zinc filings (FLAM), zinc powder (FLAM), zinc foil, zinc strip, AAS standard solution, granulated zinc.
Zince can be obtained from dry cell battery case, zinc blocks from electronics supply shops for anodes, building supplies shops sell zinc sheets for roof flashing.
Zinc dust is dangerous as a fine powder and the powder is not permitted in schools.
It is highly flammable, ignites on heating, forms explosive mixtures with S, Br2, I2, explosive if finely dispersed in air, Toxic if inhaled.
Zinc dust, that is flammable and has been used in the past to make rocket fuel by mixing it with finely-divided sulfur.
Zinc dust is highly flammable.
Zinc dust, ignites on heating, explosive mixtures with S, Br2, I2, explosive if finely dispersed in air, Toxic if inhaled.
Zinc / sulfur mixtures are hazardous, liable to combust violently on ignition and release large amounts of sulfur dioxide from oxidation of unreacted sulfur.
Zinc dust forms hazardous mixtures with iodine and many oxidizing agents, e.g. manganese dioxide, potassium nitrate and potassium permanganate.
Use zinc powder, or granulated zinc, foil or low cost casing of unused zinc-carbon battery (99%+ zinc), for teaching about:
| electrochemical cells | reactivity of metals | displacement reactions | form hydrogen with dilute acids | the surface layer of zinc on galvanized iron sheets.
Zinc is used as foil in a dry cell battery casings, alloys and brass, as a micro nutrient (trace element) as salts or compounds, not as the pure element.
Zinc anodes for electroplating industry, increase life of high carbon steel fishing hooks.
Zinc anode nuts to protect underground and submerged threads.
Time release anodes to release fishing pots.
Zinc string and zinc ribbon to protect double bottom tanks of ships, mooring chains, underground storage tanks and pipelines.
Zinc G-clamps and I-bolts to attach anode to structures.
Brass is an alloy of copper and zinc.
Hydrozincite, Zn[(OH)3CO3], zinc bloom
US cent coins minted in 1983, zinc + thin copper plating
Zinc is extracted from zinc blende (sphalerite, ZnS)
High level of zinc in the diet is undesirable, e.g. from eating too many oysters.
Zinc deficiency symptoms occur where people live on unleavened bread made from highly extracted wheat flour and no meat or yeast products in the diet.
Zinc is a cofactor for about 20 enzymes, e.g. alcohol dehydrogenase that breaks down ethanol and carboxypeptidase that catalyses the hydrolysis of proteins.
The recommended daily allowance, RDA, is 15 mg for males and 12 mg for females.
Atomic number: 30, Relative atomic mass: 65.39, RD 7.14, MP = 420 oC , BP = 907 oC .
Specific heat capacity: 385 J kg-1 K-1.

Zinc: 35.2.73, (Geology)
Zinc chloride battery: 33.4.53.1, (many zince batteries below on this page)
Leclanché cell: 33.4.53.0, electric torch battery, flashlight battery
Zinc blende: 35.2.64, (Geology)
Zincite: 35.2.74, (Geology)
Zinc compounds
Zinc deficiency in soils: 6.13.9, (Agriculture)
Zinc residues: 3.3.7, (disposal)
Zinc toxicity: 4.16, (Safety)

Zinc experiments
Dilute hydrochloric acid with zinc: 17.1.6, (count bubbles)
Heat of displacement reaction: 14.1.6
Heat zinc with copper (II) oxide: 12.13.11
Heat zinc with sulfur: 12.2.10.7, Synthesis reactions
Iron and zinc with copper (II) sulfate solution: 12.14.12
Magnesium, or zinc, with copper (II) sulfate solution: 12.14.10
Prepare hydrogen gas: 13.3.15, zinc with dilute hydrochloric acid
Prepare zinc sulfate crystals: 12.10.8
Test a simple cell with different metals: 33.1.3.12, (zinc strip)
Test a simple electric cell with copper and zinc in dilute sulfuric acid: 33.1.7.10, (piece of zinc)
Tests for zinc: 12.11.3.30
Reactions of metals as reducing agents, Zinc experiments: 12.14.13a
Zinc plating of copper: 15.1.6, (zinc chloride)

Zinc compounds
Copper-zinc alloys, brass: 5.1.10
Smithsonite: 35.2.63, (ZnCO3), (Geology)
Sphalerite: 25.2.64, (ZnS), (Geology)
Zinc acetate dihydrate, C4H6O4Zn·2H2O or C4H10O6Zn, zinc ethanoate ZnC4H6O4, harmful if ingested, white granules, slightly efflorescent, faint vinegar odour.
Zinc bloom, hydrozincite, marionite, Zn5(CO3)2(OH)6, Zn[(OH)3(CO3)]2.5H2O, weathering production zinc deposit
Zinc carbonate, ZnCO3
Zinc (II) chloride
Zinc chromate, ZnCrO4
Zinc cyanide, Zn(CN)2, white powder, or colourless, rhombic crystals, bitter almonds odour, decomposes at 800 oC
Zinc fluoride, ZnF2, ZnF2.4H2O, colourless crystals, needles, white crystalline mass, melting point of 872 oC
Zinc gluconate, C12H22O14Zn, in medicine for common cold
Zinc nitrate, Zn(NO3)2
Zinc oxide, ZnO
Zinc phosphate, Zn3(PO4)2, primer, rust prevention
Zinc phosphide, Zn3P2, dark grey crystals, or lustrous or dull powder, faint phosphorus or garlic odour, rat bait
Zinc potassium chromate, KZn2.(OH)(CrO4)2, yellow powder, green-yellow, odourless, metal priming paint against corrosion
Zinc sulfate, ZnSO4
Zinc sulfide, ZnS
Zinc sulfite, ZnSO3, zinc sulfite dihydrate
Zincate, Zn(OH)42
Zincite, Geology)
Zineb, C4H6N2S4Zn, fungicide: 4.3.10

Zinc carbonate, ZnCO3
Zinc carbonate, colourless crystals or white crystalline powder, odourless, harmful, evolves carbon dioxide at 300 oC
Zinc carbonate, ZnCO3 (basic zinc carbonate, ZnCO3.2ZnO.3H2O
Zinc carbonate basic, ZnCO3.2ZnO.3H2O, smithsonite, calamine (calamine lotion for itches and rashes)

Zinc (II) chloride, ZnCl2
Zinc (II) chloride anhydrous, ZnCl2, Harmful if ingested, corrosive to skin, eyes
Zinc chloride, Solution / mixture < 5%, Not hazardous, hygroscopic white granules or crystals, fused pieces, or rods, melts at 275 oC
Zinc chloride (soln), 32% in HCl soldering flux, "killed acid", tinner's fluid, butter of zinc, Harmful
Zinc chloride, killed acid, Append E, Environment danger, Corrosive, (COR 2331), used to clean copper

Zinc chromate, ZnCrO4
Zinc chromate is used as a yellow rust-prevention primer on Fe and Al, but chromium toxicity against such use
Highly toxic if ingested or absorbed through skin, do not inhale yellow, fine powder or yellow prisms, odourless
Zinc chromate, Solution / mixture < 0.1%, Not hazardous
Zinc chromite, chromium zinc oxide, ZnO.xCr2O3

Zinc nitrate, Zn(NO3)2
Zinc nitrate hexahydrate, hydrated, Zn(NO3)2.6H2O, Harmful if ingested
Zinc nitrate, Explosive mixtures with combustibles and organic compounds, toxic fumes

Zinc oxide, ZnO
Zinc oxide, ZnO, amphoteric (sunscreen cream)
Zinc oxide, flowers of zinc, philosopher's wool, spartalite, zincite, zinc white, Chinese white
Zinc oxide, white solid turns yellow on heating, melting point 1975 oC
Zinc oxide with ammonium nitrate and some water may explode
Zinc oxide, ZnO, white to yellow, amorphous powder, RD 5.47, MP above 1 800 oC , white pigment, zincite, white zinc, zinc white
Chinese white, spartalite, craft, zinc sun cream medicine and other skin problems

Zinc sulfate, ZnSO4
Zinc sulfate, ZnSO4, zinc sulfate(VI)-7-water, zinc sulfate heptahydrate, ZnSO4.7H2O (electrochemical cells), Harmful if ingested, sulfur dioxide formed when heated
Zinc sulfate, colourless rhombic crystals, transparent prisms or small needles, efflorescent in dry air
Zinc sulfate heptahydrate, ZnSO4.7H2O, For 0.1 M solution, 28.8 g in 1 L water
Zinc sulfate hydrated, goslarite, white vitriol, white copperas
Zinc sulfate monohydrate, ZnSO4.H2O, zinc sulfate heptahydrate, ZnSO4.7H2O, colourless, odourless, white rhombic crystals or powder,
RD 1.97, MP about 50 oC , efflorescent in dry air, anhydrous at 200 oC , decomposes above 500 oC ,
white vitriol, zinc vitriol, white copperas, gosla rite, in zinc deficiency medicines
Prepare zinc sulfate crystals: 12.10.8
Sodium hydroxide with zinc sulfate solution: 12.1.10
Tests for oxidizing agents by change in colour of zinc with copper (II) sulfate: 15.4.17, (See: 3.)

Zinc sulfide, ZnS
Zinc sulfide, ZnS, white-yellow solid, soluble, sublimes, phosphor, pigment, Toxic if ingested, skin irritant
Zinc sulfide, ZnS, colourless hexagonal crystals, or white / grey-white powder or yellow powder, in sphalerite
Zinc sulfide with acids forms hydrogen sulfide gas

Zirconium, Zr
Zirconium Table of the Elements
Zirconium, RSC
Zirconium, Zr, is a grey amorphous powder, which may ignite spontaneously by static electricity and explode with geat intensity, especially in water.
Zirconium, Zr, (German zirkon zircon, zirconium ore), grey-white solid, lustrous transition metal
SPADNS fluoride reagent solution, 500 mL, C16H9N2Na3O11S3, [(HO)2C10H3(SO3Na)2N=NC6H4SO3Na], indicator for zirconium
Zirconium is used to make corrosion-resistant alloys, pyrotechnics, alloys to resist corrosion, nuclear fuel rods, photography flash bulbs, e.g. "Magicube".
It is a nuclear reactor neutron absorber
An "iSlice Cutter" has an zirconium-oxide ceramic blade that never rusts!

Zircon, ZrSiO4
2. Zircon, ZrSiO4, zirconium silicate, zirconium (IV) silicate, zirconium (IV) silicon oxide, zircon sand
Zircon, jacinth, jargoons, matura diamonds, in ceramic glazes
Zircon, Separate solids, density differences: 3.27
Zirconium, pegmatite, ZrSiO4, silicate: 35.2.9, (Geology)
Zircon, green zircon, ZrSiO4, a silicate of zirconium, a rare mineral, which may also occur as crystals in pegmatite:

Zirconia, ZrO2
Zirconia, ZrO2, zirconium dioxide, zirconia, zircon (IV) oxide, zircon-favas, white crystalline oxide, occurs in Baddeleyite mineral.
Cubic zirconia (CZ), optically flawless, colourless, crystalline zirconium dioxide, synthetic jewellery, zirconia dental crowns, 8.5 Mohs hardness scale
Pink zirconia, diamond look-alike, zirconium dioxide, synthetic jewellery

Zirconium nitrate, Zr(NO3)4br> 3. Zirconium nitrate, Zr(NO3)4, Toxic if ingested, inhalation harmful, skin sensitization, explosion by shock or friction or ignition
Zirconium nitrate with acids forms nitrogen dioxide gas
Zirconium dioxide + nitric acid --> Zirconium nitrate pentahydrate Zr(NO3)4·5H2O Other zirconium compounds
Zirconate, lead-zirconate-titanate (PZT), Piezoelectricity: 32.1.2.1
Zirconium tungstate, ZrW2O8, and Zirconium vanadate, ZrV2O7, negative thermal expansion

12.21.1 Reactions of zinc and zinc compounds
1. Hold a piece of zinc foil in the Bunsen burner flame, using tongs.
Note the zinc oxide forms that is yellow when hot and white when cold.
2. Add sodium carbonate solution to zinc sulfate solution.
Observe the white precipitate of basic zinc carbonate, ZnCO3.2Zn(OH)2H2O.
3. Add sodium hydrogen carbonate to zinc sulfate solution.
Note the white precipitate of the normal carbonate, ZnCO3.
4. Add drops of sodium hydroxide solution to zinc sulfate solution.
Observe the white precipitate of zinc hydroxide that dissolves in excess of sodium hydroxide solution to form sodium zincate.
Pass hydrogen sulfide is passed through the sodium zincate solution.
Note the white precipitate of zinc sulfide.
Zinc hydroxide is amphoteric.
ZnSO4 + 2NaOH --> Zn(OH)2 + Na2SO4
Zn(OH)2 + 2NaOH --> Na2ZnO2 + 2H2O
(Note: Na2ZnO2 is sodium zincate)
5. Add drops of ammonium sulfide solution to zinc sulfate solution.
Note the white precipitate of zinc sulfide that may be discoloured.
6. Dip a rolled filter paper into a concentrated solution of zinc sulfate with added cobalt nitrate solution.
Burn the filter paper on wire gauze and note the remaining green ash, Rinmann's green.
7. Add drops of ammonium hydroxide to zinc sulfate solution.
The precipitate of zinc hydroxide dissolves in excess, due to the formation of a complex ion, [Zn(NH3)2]2+.

Phenolic compounds, by name
Anethole
Arbutin
Bergenin
Caffeic acid
Capsaicin
Carvacrol
Catechol
Chlorogenic acid
Cichoric acid
Cinnamaldehyde
Cinnamic acid
Coumarin
Cresol
Curcumin
Cyanidin
Emodin
Ethylphenol
Estradiol (oestradiol), C18H24O2
Estragole
Eugenol
Ferulic acid
Furanocoumarins
Gallic acid
Genistein, C15H10O5, occurs in soy, alfalfa, red clover, chickpeas, peanuts
Guaiacol, Methyoxyphenol
Juglone
Mangiferin
Methyl salicylate
Myristicin
Nordihydroguaiaretic acid
O-leuropein
Paeonol
Piceatannol
Plumbagin
Quercetin
Raspberry ketone
Resorcinol
Resveratrol Rosmarinic Acid
Salicyclic acid
Sesamol
Shikonin
Shogoal
Silibinin
Sinapinic acid
Tannic acid
Thymol
Tyrosine
Tyrosol
Umbelliferone
Urushiol
Vanillin
Zingerone

Senior chemistry.
Chemical systems may be open or closed.
Physical changes are usually reversible, whereas only some chemical reactions are reversible.
Observable changes in chemical reactions and physical changes can be described and explained at an atomic and molecular level.
Equilibrium equations can be symbolized by using ⇋ in balanced chemical equations.
Eventually, physical changes & reversible chemical reactions reach a state of dynamic equilibrium in a closed system.
The reversibility of chemical reactions can be explained by considering Ea of the forward and reverse reactions.
Use the relative changes in the concentration of reactants and product against time, to identify the position of equilibrium.
Factors affecting equilibrium The effect of temperature change on chemical systems at equilibrium can be explained by considering the enthalpy change for the forward and reverse reactions.
Le Châtelier’s principle can be used to predict the effect changes of temperature, concentration of chemicals, pressure and the addition of a catalyst have on the position of equilibrium and on the value of the equilibrium constant.
Equilibrium constants The equilibrium constant (Kc), at any given temperature, indicates the relationship between product and reactant concentrations at equilibrium.
Use equilibrium constants (Kc), to predict qualitatively, the relative amounts of reactants and products (equilibrium position).
The extent of a reaction can be deduced from the magnitude of the equilibrium constant.
Properties of acids & bases Acids are substances that can act as proton (hydrogen ion) donors and can be classified as monoprotic or polyprotic depending on the number of protons donated by each molecule of the acid.
Strong & weak acids & bases can be described in terms of the extent of dissociation, reaction with water & electrical conductivity.
Water is a weak electrolyte and the self-ionisation of water is represented by Kw = [H+][OH-]; Kw can be used to calculate the concentration of hydrogen ions from the concentration of hydroxide ions in a solution.
The pH scale is a logarithmic scale and the pH of a solution can be calculated from the concentration of hydrogen ions using the relationship pH = –log10[H+].
Brønsted-Lowry model The relationship between acids & bases in equilibrium systems can be explained using the Brønsted-Lowry model & represented using chemical equations that illustrate the transfer of H+ (protons) between conjugate acid-base pairs.
Buffers are solutions that are conjugate in nature & resist a change in pH when a small amount of an acid or base is added; Le Châtelier’s principle can be applied to predict how buffer solutions respond to the addition of hydrogen ions & hydroxide ions.
Dissociation constants Recognise that the strength of acids is explained by the degree of ionisation at equilibrium in aqueous solution, which can be represented with chemical equations and equilibrium constants (Ka).
Determine the expression for the dissociation constant for weak acids (Ka) and weak bases (Kb) from balanced chemical equations.
Analyse experimental data to determine and compare the relative strengths of acids and base.
Use appropriate mathematical representation to solve problems, including calculating dissociation constants (Ka and Kb) and the concentration of reactants and products.
Acid-base indicators Understand that an acid-base indicator is a weak acid or weak base, where components of the conjugate acid-base pair have different colours; the acidic form is a different colour to the basic form.
Explain the relationship between the pH range of an acid-base indicator and its pKa value.
Recognise that indicators change colour when the pH = pKa and identify an appropriate indicator for a titration, given equivalence point of the titration and pH range of the indicator.
Volumetric analysis Distinguish between the terms end point and equivalence point.
Recognise that acid-base titrations rely on the identification of an equivalence point by measuring the associated change in pH, using chemical indicators or pH meters, to reveal an observable end point.
Sketch the general shapes of graphs of pH against volume (titration curves) involving strong & weak acids & bases.
Identify & explain their important features, including the intercept with pH axis, equivalence point, buffer region & points where pKa = pH or pKb = pOH.
Use appropriate mathematical representations & analyse experimental data & titration curves to solve problems and make predictions, including using the mole concept to calculate moles, mass, volume & concentration from titration data.
Mandatory practical: Acid-base titration to calculate the concentration of a solution with reference to a standard solution.
Redox reactions Recognise that a range of reactions, including displacement reactions of metals, combustion, corrosion and electrochemical processes, can be modelled as redox reactions involving oxidation of one substance and reduction of another substance.
Understand that the ability of an atom to gain or lose electrons can be predicted from the atom’s position in the periodic table, and explained with reference to valence electrons, consideration of energy and the overall stability of the atom.
Identify the species oxidised and reduced, and the oxidising agent and reducing agent, in redox reactions.
Understand that oxidation can be modelled as the loss of electrons from a chemical species, and reduction can be modelled as the gain of electrons by a chemical species; these processes can be represented using balanced half-equations and redox equations (acidic conditions only).
Deduce the oxidation state of an atom in an ion or compound and name transitional metal compounds from a given formula by applying oxidation numbers represented as roman numerals.
Use appropriate representations, including half-equations and oxidation numbers, to communicate conceptual understanding, solve problems and make predictions.
Cells Understand that electrochemical cells, including galvanic and electrolytic cells, consist of oxidation and reduction half-reactions connected via an external circuit that allows electrons to move from the anode (oxidation reaction) to the cathode (reduction reaction).
Understand that galvanic cells, including fuel cells, generate an electrical potential difference from a spontaneous redox reaction which can be represented as cell diagrams including anode and cathode half-equations.
Recognise that oxidation occurs at the negative electrode (anode) and reduction occurs at the positive electrode (cathode) and explain how two half-cells can be connected by a salt bridge to create a voltaic cell (examples of half-cells are Mg, Zn, Fe and Cu and their solutions of ions).
Describe, using a diagram, the essential components of a galvanic cell; including the oxidation and reduction half-cells, the positive and negative electrodes and their solutions of their ions, the flow of electrons and the movement of ions, and the salt bridge.
Discuss, using diagrams and relevant half-equations, the operation of a hydrogen fuel cell under acidic and alkaline conditions.
Standard electrode potentials Determine the relative strength of oxidising and reducing agents by comparing standard electrode potentials.
Recognise that cell potentials at standard conditions can be calculated from standard electrode potentials; these values can be used to compare cells constructed from different materials.
Recognise the limitation associated with standard reduction potentials.
Use appropriate mathematical representation to solve problems and make predictions about spontaneous reactions, including calculating cell potentials under standard conditions.
Electrolytic cells use an external electrical potential difference to provide the energy to allow a non-spontaneous redox reaction to occur.
They can be used in small-scale and industrial situations, including metal plating and the purification of copper.
Predict and explain the products of the electrolysis of a molten salt and aqueous solutions of sodium chloride and copper sulfate.
Explanations should refer to Eo values, the nature of the electrolyte and the concentration of the electrolyte.
Organic molecules have a hydrocarbon skeleton and can contain functional groups, including alkenes, alcohols, aldehydes, ketones, carboxylic acids, haloalkanes, esters, nitriles, amines, amides and that structural formulas (condensed and extended) can be used to show the arrangement of atoms and bonding in organic molecules.
Use IUPAC rules in the nomenclature of organic compounds (parent chain up to 10 carbon atoms) with simple branching for alkanes, alkenes, alkynes, alcohols, aldehydes, ketones, carboxylic acids, haloalkanes, esters, nitriles, amines and amides.
Identify structural isomers as compounds with the same molecular formula but different arrangement of atoms; deduce the structural formulas and apply IUPAC rules in the nomenclature for isomers of the non-cyclic alkanes up to C6.
Stereoisomers are compounds with the same structural formula but with different arrangement of atoms in space; describe and explain geometrical (cis and trans) isomerism in non-cyclic alkenes.
Organic compounds display characteristic physical properties, including melting point, boiling point and solubility in water and organic solvents that can be explained in terms of intermolecular forces (dispersion forces, dipole-dipole interactions and hydrogen bonds), which are influenced by the nature of the functional groups.
Each class of organic compound displays characteristic chemical properties and undergoes specific reactions based on the functional group present; these reactions, including acid-base and oxidation reactions, can be used to identify the class of the organic compound.
Ssaturated compounds contain single bonds only and undergo substitution reactions, and that unsaturated compounds contain double or triple bonds and undergo addition reactions.
Describe, using equations: · oxidation reactions of alcohols and the complete combustion of alkanes and alcohols · substitution reactions of alkanes with halogens · substitution reactions of haloalkanes with halogens, sodium hydroxide, ammonia and potassium cyanide · addition reactions of alkenes with water, halogens and hydrogen halides · addition reactions of alkenes to form poly(alkenes).
Esterification is a reversible reaction between an alcohol and a carboxylic acid.
Amines with carboxylic acids form amides.
Esters and amides are formed by condensation reactions.
Distinguish between alkanes and alkenes using bromine water Distinguish between primary, secondary and tertiary alcohols using acidified potassium dichromate (VI) and potassium manganate (VII).
The synthesis of organic compounds often involves constructing reaction pathways that may include more than one chemical reaction.
Organic materials including proteins, carbohydrates, lipids and synthetic polymers display properties including strength, density and biodegradability that can be explained by considering the primary, secondary and tertiary structures of the materials.
The primary, secondary (α-helix and β-pleated sheets), tertiary and quaternary structure of proteins.
Enzymes are proteins and describe the characteristics of biological catalysts (enzymes) including that activity depends on the structure and the specificity of the enzyme action.
Monosaccharides contain either an aldehyde group (aldose) or a ketone group (ketose) and several -OH groups, and have the empirical formula CH2O.
Distinguish between α-glucose and β-glucose, and compare and explain the structural properties of starch (amylose and amylopectin) and cellulose.
Triglycerides (lipids) are esters and describe the difference in structure between saturated and unsaturated fatty acids.
By using equations, the base hydrolysis (saponification) of fats (triglycerides) to produce glycerol and its long chain fatty acid salt (soap), and explain how their cleaning action and solubility in hard water is related to their chemical structure.
The properties of polymers depends on their structural features including; the degree of branching in polyethene (LDPE and HDPE), the position of the methyl group in polypropene (syntactic, isotactic and atactic) and polytetrafluorethene.
Proteins can be analysed by chromatography and electrophoresis.
Use data from analytical techniques, including mass spectrometry, x-ray crystallography and infrared spectroscopy, to determine the structure of organic molecules.
Analyse data from spectra, including mass spectrometry and infrared spectroscopy, to communicate conceptual understanding, solve problems and make predictions.
Reagents and reaction conditions are chosen to optimise the yield and rate for chemical synthesis processes, including the production of ammonia (Haber process), sulfuric acid (contact process) and biodiesel (base-catalysed and lipase-catalysed methods).
Fuels, including biodiesel, ethanol and hydrogen, can be synthesised from a range of chemical reactions including, addition, oxidation and esterification.
Enzymes can be used on an industrial scale for chemical synthesis to achieve an economically viable rate, including fermentation to produce ethanol and lipase-catalysed transesterification to produce biodiesel.
The production of ethanol from fermentation and the hydration of ethene.
Transesterification of triglycerides to produce biodiesel.
Calculate the yield of chemical synthesis reactions by comparing stoichiometric quantities with actual quantities and by determining limiting reagents.
Green chemistry principles include the design of chemical synthesis processes that use renewable raw materials, limit the use of potentially harmful solvents and minimise the amount of unwanted products.
The higher the atom economy, the ‘greener’ the process.
The economic and environmental impact of chemical synthesis processes.
Macromolecules: polymers, proteins and carbohydrates Polymers can be produced from their monomers including polyethene (LDPE and HDPE), polypropene and polytetrafluorethene.
Condensation polymers, including polypeptides (proteins), polysaccharides (carbohydrates) and polyesters, can be produced from their monomers.
The advantages and disadvantages of polymer use, including strength, density, lack of reactivity, use of natural resources and biodegradability.
Condensation reaction of 2-amino acids to form polypeptides (involving up to three amino acids), and understand that polypeptides (proteins) are formed when amino acid monomers are joined by peptide bonds.
Condensation reaction of monosaccharides to form disaccharides (lactose, maltose and sucrose) and polysaccharides (starch, glycogen and cellulose), and understand that polysaccharides are formed when monosaccharides monomers are joined by glycosidic bonds.
Molecular manufacturing processes involve the positioning of molecules to facilitate a specific chemical reaction; such methods have the potential to synthesise specialised products, including proteins, carbon nanotubes, nanorobots and chemical sensors used in medicine.