This week on The Missing Workbook
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Word
English Vocabulary
Pick a CEFR level (A1–C2, plus C2+ for rare words beyond the CEFR scale) — A1 is the friendliest place to start — and browse its words grouped by topic: travel, food, the body, emotions, and more. Each word shows its meaning, example sentences, and US/UK pronunciation.
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All 27,899 wordsC2+ is beyond the official CEFR scale: rare, specialist, and literary words kept for reference.
50 words
iron
B1
/æːn/
A common hard grey metal that rusts and is used to make steel
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solution
A2
/səˈl(j)uːʃən/
A way of solving a problem or dealing with a difficult situation.
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reaction
B1
/ɹiˈækʃən/
The way you behave or feel because of something that has happened.
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crystal
C1
/ˈkɹɪstəl/
A clear, solid mineral form with a regular geometric shape; high-quality clear glass.
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chemical
A2
/ˈkɛm.ɪ.kəl/
A substance, such as an element or compound, used in or produced by chemistry.
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acid
B2
/ˈæsəd/
A chemical substance, often sour or corrosive, that reacts with bases and can dissolve metals.
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element
B1
/ˈɛləmənt/
One of the parts that together make up a whole.
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copper
B2
/ˈkɑpəɹ/
A soft reddish-brown metal (symbol Cu) used in wires, pipes, and coins.
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chemistry
B1
/ˈkɛm.ɪ.stɹi/
The science that studies what substances are made of and how they change.
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carbon
B2
/ˈkɑɹ.bən/
A chemical element (symbol C) found in all living things, and in forms such as graphite and diamond.
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compound¹
B1
/ˈkɑmpaʊnd/
a substance made by combining two or more elements or ingredients
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laboratory
B1
/ˈlæb(ə)ɹəˌtɔɹi/
A room or building equipped for scientific research, experiments, or analysis.
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concentration
B1
/ˌkɑn.sənˈtɹeɪ.ʃən/
the ability to give all your attention to something
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hydrogen
C1
/ˈhaɪdɹəd͡ʒ(ə)n/
The lightest chemical element (symbol H), a colorless, odorless, highly flammable gas.
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atom
A2
/ˈætəm/
The smallest part of a chemical element that can exist.
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chemist
B1
/ˈkɛmɪst/
A scientist who studies or works with chemistry.
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sodium
B1
/ˈsoʊ.di.əm/
Employing sodium.
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dioxide
B1
/daɪˈɑksaɪd/
A chemical compound that has two oxygen atoms in each molecule.
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nitrogen
B1
/ˈnaɪ.tɹə.d͡ʒən/
The chemical element with an atomic number of 7 and atomic weight of 14.0067. It is a colorless and odorless gas.
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reduction
B1
/ɹɪˈdak.ʃən/
The act of making something smaller or less.
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calcium
B1
/ˈkæl.si.əm/
the chemical element with symbol Ca and atomic number 20, a soft, silvery, reactive alkaline-earth metal that occurs naturally only in compounds
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potassium
B2
/pəˈtæs.i.əm/
the chemical element with symbol K and atomic number 19, a soft, silvery, highly reactive alkali metal that occurs naturally only in compounds
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nucleus
B1
/ˈnuː.kli.əs/
The central part of an atom, made of protons and neutrons.
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ion
B2
/ˈaɪ.ɑn/
an atom or group of atoms with a positive or negative electrical charge because it has lost or gained electrons
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electron
B1
/ɪˈlɛk.tɹɑn/
A tiny particle inside an atom that carries a negative electric charge.
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sulfur
B2
/ˈsʊl.fə/
A bright yellow chemical element (symbol S) with a strong smell, used in matches, gunpowder, and many industrial products.
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molecule
B1
/ˈmɑ.lɪ.kjul/
The smallest unit of a substance that still has all its chemical properties, made of two or more atoms joined together.
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neutron
B2
/ˈnu.tɹɑn/
an elementary particle with 0 charge and mass about equal to a proton
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chlorine
C1
/ˈklɔːr.iːn/
the chemical element with atomic number 17, a toxic greenish-yellow halogen gas in its elemental form
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combustion
C2
/kəmˈbʌs.t͡ʃən/
The process of burning, in which a substance reacts with oxygen to produce heat and light.
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oxide
B1
/ˈɑksaɪd/
a chemical compound of oxygen with another element
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nitrate
C2
/ˈnaɪ.treɪt/
a salt or ester of nitric acid, containing the nitrate ion or nitrate group
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enzyme
B2
/ˈɛn.zaɪm/
a protein or RNA molecule that catalyzes a biochemical reaction without being consumed by it
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magnesium
B2
/ˌmæɡˈnizi.əm/
the chemical element with atomic number 12, a light, silvery-white metal that burns with an intense white flame
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proton
B2
/ˈpɹoʊ.tɑn/
A positively charged subatomic particle forming part of the nucleus of an atom and determining the atomic number of an element, composed of two up quarks and a down quark.
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beaker
B2
/ˈbiː.kɚ/
a straight-sided, flat-bottomed laboratory container, usually with a pouring lip
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isotope
C2
/ˈaɪ.sə.toʊp/
one of two or more atoms with the same atomic number but with different numbers of neutrons
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sulfate
C2
/ˈsʌlfeɪt/
Any salt or ester of sulfuric acid.
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corrosion
C2+
/kəˈɹoʊʒən/
The gradual destruction or undermining of something.
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evaporation
B2
/ɪˌvæpəˈreɪʃən/
the process by which a liquid changes into a gas, especially at its surface
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distillation
C2
/ˌdɪstɪˈleɪʃən/
The process of purifying a liquid by boiling it and condensing the vapor.
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reagent
C2
/riˈeɪ.dʒənt/
a substance or mixture used to cause, detect, measure, or investigate a chemical reaction
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electrolysis
C2
/ˌɛˌlɛkˈtrɑːləsɪs/
The chemical change produced by passing an electric current through a conducting solution or a molten salt.
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crystallization
C2
/ˌkɹ̠ɪstəlaɪˈzeɪʃən/
The process of becoming clear, definite, or precise.
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pipette
C2
/paɪˈpet/
a narrow graduated tube used to measure or transfer a small quantity of liquid
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precipitate
C2+
/prɪˈsɪpɪteɪt/
to cause to happen suddenly; hasty; a solid separated from a solution
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precipitation
C2+
/prɪˌsɪpɪˈteɪʃən/
rain, snow, or other water falling from the sky; hasty action
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alkali
C2+
/ˈælkəˌlaɪ/
a soluble base that neutralizes acids, turning litmus blue
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polymer
C1
/ˈpɑləmɚ/
a large molecule made of many repeating smaller units linked together, or a material consisting of such molecules
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chromatography
C2
/kɹoʊməˈtɑɡɹəfi/
a method of separating the components of a mixture by their different movement through a stationary material as a fluid passes over or through it
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