chemistry

Carbon nanotubes are cylindrical carbon structures with extraordinary tensile strength and electrical properties.

Saponification is the alkaline hydrolysis of fats or oils to produce soap and glycerol.

Esterification is the reaction between an alcohol and a carboxylic acid to form an ester and water.

The Periodic Table was first formulated by Dmitri Mendeleev in 1869.

The first synthetic plastic, Bakelite, was invented by Leo Baekeland in 1907.

Aluminum is the most abundant metal in Earth's crust and is widely used due to its low density and corrosion resistance.

Glass is an amorphous solid, typically based on silica, that lacks a regular crystalline structure.

Half-life is the time required for half of a quantity of a radioactive substance to decay.

Radioactive decay is the spontaneous transformation of an unstable atomic nucleus into a more stable one, emitting radiation.

Isotopes are atoms of the same element with different numbers of neutrons.

The mole concept relates the number of particles to the mass of a substance through Avogadro's number.

Le Chatelier's principle states that a system at equilibrium will shift to counteract an applied stress.

Graphene, isolated in 2004, is a two-dimensional sheet of carbon atoms with remarkable electronic and mechanical properties.

Buffer solutions resist changes in pH when small amounts of acid or base are added.

Acids in aqueous solution donate hydrogen ions, while bases accept them.

Nylon, the first fully synthetic fiber, was developed by Wallace Carothers at DuPont in 1935.

Steel is an iron-carbon alloy with carbon content typically between 0.02 and 2 percent by mass.

The Haber process synthesizes ammonia from nitrogen and hydrogen and is essential for industrial fertilizer production.

Stoichiometry is the calculation of relative quantities of reactants and products in chemical reactions.

Carbon has six protons and is the basis of all known organic chemistry.

The periodic table currently contains 118 confirmed elements, with element 118 being oganesson.

The 2019 Nobel Prize in Chemistry was awarded to John Goodenough, Stanley Whittingham, and Akira Yoshino for the development of lithium-ion batteries.

Catalysts increase the rate of chemical reactions without being consumed in the process.

Combustion is a high-temperature exothermic chemical reaction between a fuel and an oxidant, typically producing heat and light.

An exothermic reaction releases heat to its surroundings, while an endothermic reaction absorbs heat.

Carbon dioxide has the chemical formula CO2 and is produced by combustion and respiration.

Ammonia has the chemical formula NH3 and is widely used in fertilizer production.

Helium is the second most abundant element in the universe and is chemically inert.

Oxygen makes up approximately 21 percent of Earth's atmosphere by volume and is essential for aerobic respiration.

The halogens, group 17 of the periodic table, include fluorine, chlorine, bromine, iodine, and astatine.

Marie Curie was the first person to win Nobel Prizes in two different sciences, for physics in 1903 and chemistry in 1911.

Acid rain forms when sulfur and nitrogen oxides react with water in the atmosphere, producing sulfuric and nitric acids.

Water has the chemical formula H2O, consisting of two hydrogen atoms covalently bonded to one oxygen atom.

Avogadro's number, the number of constituent particles in one mole, is exactly 6.02214076 x 10^23 since the 2019 SI redefinition.

Gold has the chemical symbol Au, derived from the Latin word aurum.

The pH scale runs from 0 to 14, where 7 is neutral, lower values are acidic, and higher values are basic.

Electrolysis uses an electric current to drive an otherwise non-spontaneous chemical reaction.

Oxidation is loss of electrons, and reduction is gain of electrons, with the two processes always occurring together in redox reactions.

Sodium chloride is the chemical name for common table salt.

Methane has the chemical formula CH4 and is the principal component of natural gas.

Glucose has the chemical formula C6H12O6 and is a primary energy source for cellular respiration.

Hydrogen is the lightest and most abundant chemical element in the universe.

The noble gases, group 18 of the periodic table, are helium, neon, argon, krypton, xenon, and radon.

Diamond and graphite are both pure carbon but differ in atomic structure, giving them very different physical properties.

Stainless steel is an iron-based alloy containing at least 10.5 percent chromium by mass.

The mole is the SI unit of amount of substance, defined as containing exactly 6.02214076 x 10^23 elementary entities.

Iron rusts when exposed to oxygen and moisture, forming hydrated iron oxides.

Saturated fats have no double bonds between carbon atoms, while unsaturated fats have one or more such double bonds.

Polymers are large molecules composed of many repeated subunits called monomers.

Plastics are synthetic polymers that can be molded into various shapes; common types include polyethylene, polypropylene, and polyvinyl chloride.

Carbon dating uses the decay of carbon-14 to estimate the age of organic materials up to about 50,000 years old.

Crude oil is a naturally occurring liquid hydrocarbon that is refined into products such as gasoline, diesel, and jet fuel.

Natural gas, primarily methane, is a fossil fuel formed from the decomposition of organic matter over millions of years.

TEST CLAIM: Avogadro's number is approximately 6.022 times 10 to the 23rd particles per mole.