Documented below are some frequently asked chemistry questions. The Art of Chemistry – no previous experience required – offers answers to them all in a great deal more detail. Furthermore, the FAQs below are taken from its 365 term glossary.
What are alpha particles?
A positively charged particle, consisting of two protons and two neutrons, emitted from the nucleus of a decaying atom.
What is the acid dissociation constant Ka?
The point at which an acid achieves dynamic chemical equilibrium. It is calculated with the acid equilibrium expression. Ka = [H+][A–] / [HA]
What is an aromatic compound?
Compounds that have a ring of carbon atoms containing delocalised π (pi) electrons whose number equals 4n+2, where n is an integer equal to or greater than one. A π (pi) electron forms part of a pi bond – a covalent bond, where two lobes of an orbital overlap with two lobes of an orbital on another atom.
Note: some publications define aromatic compounts as compounds with alternating single and double bonds. This is an incorrect definition. The Art of Chemistry – no previous experience required – offers some historical information that may have led to such a definition becoming adopted by some.
More information about aromatic compounds can be found on on this third party website.
What is boltzmann’s constant?
the average kinetic energy per temperature increment per particle (N) of gas. It is equal to 1.3806504 x 10-23 J/K (note: calculations within this publication use the five-digit rounded value of 1.3807 x 10-23)
What is a carbohydrate?
Compounds consisting of only carbon, hydrogen, and oxygen; they include monosaccharides, disaccharides (two), oligosaccharides (three to ten), polysaccharides (more than ten) and substances derived from monosaccharides, which include aldoses and ketoses.
What is a covalent bond?
A result of two or more atoms forming a molecule by sharing electrons to complete their octet.
What is a delocalised electron?
Electrons in a molecule, ion or solid metal not associated with a single atom or covalent bond.
What is an elementary entity?
Any countable object or event more usually attributed to molecules, ions, or atoms.
What does DNA stand for?
DeoxyriboNucleic Acid
What is electromagnetic radiation?
The synchronised oscillations, called waves, of an electrical and magnetic field that can transport energy between locations, as well as through a vacuum.
What is entropy?
The number of possible states a system can take on.
The sum of all the physical information not available about a close thermodynamic system.
As a dynamic property, best described as a change within a system rather than a discrete value, it increases as thermal energy increases.
The logarithm of a system’s number of microstates multiplied by Boltzmann’s constant.
What is an exothermic reaction?
The rearrangement of chemical bonds, resulting in a substance releasing energy into its surroundings.
What is fractional distillation?
A distillation process for solutions containing liquids with similar boiling points.
What is gamma radiation?
Penetrating electromagnetic radiation arising from the radioactive decay of an atom’s nucleus.
What is a half-life?
The time it takes for the sample’s concentration to halve; generally used to describe radioactive decay timescales.
What is a hydrocarbon?
The simplest organic compounds, consisting of just carbon and hydrogen.
What is a hydrometer?
An instrument used to measure the specific gravity of a liquid.
What is the ideal gas law?
A theoretical approximation to the behaviour of a real gas. It is defined as: pressure (P) multiplied by volume (V) equals the number of moles (n), multiplied by a constant (R) and temperature (T).
What is an isotope?
The same species of an element with different numbers of neutrons.
What is an isomer?
Two or more different compounds having an identical composition (i.e. the same number of atoms of each element).
What is a macromolecule?
Super large molecules – biological macromolecules consist of four major classes of compounds: carbohydrates, lipids, proteins, and nucleic acids.
What is metabolism?
The biochemical process responsible for maintaining the functions of life.
What is a mole?
One mole contains 6.02214076 x 1023 elementary entities, which is the Avogadro’s constant (NA).
What is a nucleotide?
The monomers of nucleic acids.
What is the octet rule?
The valence shell of elements, after period one, can hold up to eight electrons – the octet rule helps describe an element’s reactivity.
What is Ohm’s Law?
The current through a conductor between two points is directly proportional to the electric potential difference across the two points.
What is osmosis?
A process where there is a movement of solvent molecules from a less concentrated solution into a more concentrated solution – it continues until the concentrations of both solutions are equalised.
What is a polymer?
A substance with a molecular structure built from many repeated units bonded together.
What are precious metals?
Gold, silver, platinum, and palladium are naturally occurring metallic elements with high economic value and are historically significant as a form of currency.
What is a quadratic equation?
Standard form equations: ax2 + bx + c = 0
What is a quantum?
The smallest possible unit of action, process, or physical energy, associated with a single event or interaction.
What is a radioisotope?
An unstable atom caused by too many or too few neutrons.
What is relative atomic mass (Ar)?
The ratio of the average mass of an atom to the unified atomic mass unit; approximated to an element’s protons added to the weighted average number of neutrons across its naturally occurring isotopes.
What is RNA?
RiboNucleic Acid interprets the DNA language, acting as the messenger to a molecular protein building machine.
What is specific heat capacity?
Also known as specific heat – the quantity of heat (Q) required to raise the temperature of 1.00 g of a substance by 1.00 kelvin (1.00 OC).
What is thermodynamics?
The branch of science that studies different forms of energy and their interconversion relationships at both a physical and chemical level (thermo meaning heat, dynamics meaning change).
What is the universal gas constant?
A physical constant, where R = 8.314472 J K-1 mol-1
What is a valence shell?
The outermost shell of an atom containing at least one valence electron (a valence electron are the electrons in an element’s outermost shell).