-
Acid
An acid is a molecule or ion capable of donating a hydron (proton or hydrogen ion H+), or, alternatively, capable of forming a covalent bond with an electron pair (a Lewis acid).The first category of acids is the proton donors or Brønsted acids. In the special case of aqueous solutions, proton donors form the hydronium ion H3O+ and are known as Arrhenius acids. Brønsted and Lowry generalized the Arrhenius theory to include non-aqueous solvents. A Brønsted or Arrhenius acid usually contains a hydrogen atom bonded to a chemical structure that is still energetically favorable after loss of H+.
Aqueous Arrhenius acids have characteristic properties which provide a practical description of an acid. Acids form aqueous solutions with a sour taste, can turn blue litmus red, and react with bases and certain metals (like calcium) to form salts. The word acid is derived from the Latin acidus/acēre meaning sour. An aqueous solution of an acid has a pH less than 7 and is colloquially also referred to as ‘acid’ (as in ‘dissolved in acid’), while the strict definition refers only to the solute. A lower pH means a higher acidity, and thus a higher concentration of positive hydrogen ions in the solution. Chemicals or substances having the property of an acid are said to be acidic.
Common aqueous acids include hydrochloric acid (a solution of hydrogen chloride which is found in gastric acid in the stomach and activates digestive enzymes), acetic acid (vinegar is a dilute aqueous solution of this liquid), sulfuric acid (used in car batteries), and citric acid (found in citrus fruits). As these examples show, acids (in the colloquial sense) can be solutions or pure substances, and can be derived from acids (in the strict sense) that are solids, liquids, or gases. Strong acids and some concentrated weak acids are corrosive, but there are exceptions such as carboranes and boric acid.
The second category of acids are Lewis acids, which form a covalent bond with an electron pair. An example is boron trifluoride (BF3), whose boron atom has a vacant orbital which can form a covalent bond by sharing a lone pair of electrons on an atom in a base, for example the nitrogen atom in ammonia (NH3). Lewis considered this as a generalization of the Brønsted definition, so that an acid is a chemical species that accepts electron pairs either directly or by releasing protons (H+) into the solution, which then accept electron pairs. However, hydrogen chloride, acetic acid, and most other Brønsted-Lowry acids cannot form a covalent bond with an electron pair and are therefore not Lewis acids. Conversely, many Lewis acids are not Arrhenius or Brønsted-Lowry acids. In modern terminology, an acid is implicitly a Brønsted acid and not a Lewis acid, since chemists almost always refer to a Lewis acid explicitly as a Lewis acid.
-
Acid (adjective)
Sour, sharp, or biting to the taste; tart; having the taste of vinegar.
“acid fruits or liquors”
-
Acid (adjective)
Sour-tempered.
-
Acid (adjective)
Of or pertaining to an acid; acidic.
-
Acid (adjective)
Denoting a musical genre that is a distortion (as if hallucinogenic) of an existing genre, as in acid house, acid jazz, acid rock.
-
Acid (noun)
A sour substance.
-
Acid (noun)
Any of several classes of compound having the following properties:-
-
Acid (noun)
Any of a class of water-soluble compounds, having sour taste, that turn blue litmus red, and react with some metals to liberate hydrogen, and with bases to form salts.
-
Acid (noun)
Any compound that easily donates protons; a Brønsted acid
-
Acid (noun)
lysergic acid diethylamide (LSD)
-
Base (noun)
Something from which other things extend; a foundation.
-
Base (noun)
The starting point of a logical deduction or thought; basis.
-
Base (noun)
A permanent structure for housing military personnel and material.
-
Base (noun)
The place where decisions for an organization are made; headquarters.
-
Base (noun)
A basic but essential component or ingredient.
-
Base (noun)
A substance used as a mordant in dyeing.
-
Base (noun)
Foundation: a cosmetic cream to make the face appear uniform.
-
Base (noun)
Any of a class of generally water-soluble compounds, having bitter taste, that turn red litmus blue, and react with acids to form salts.
-
Base (noun)
Important areas in games and sports.
-
Base (noun)
A supporting, lower or bottom component of a structure or object.
-
Base (noun)
A safe zone in the children’s games of tag and hide-and-go-seek.
-
Base (noun)
The lowermost part of a column, between the shaft and the pedestal or pavement.
-
Base (noun)
A nucleotide’s nucleobase in the context of a DNA or RNA biopolymer.
-
Base (noun)
The end of a leaf, petal or similar organ where it is attached to its support.
-
Base (noun)
The name of the controlling terminal of a bipolar transistor (BJT).
-
Base (noun)
The lowest side of a in a triangle or other polygon, or the lowest face of a cone, pyramid or other polyhedron laid flat.
-
Base (noun)
The lowest third of a shield or escutcheon.
-
Base (noun)
The lower part of the field. See escutcheon.
-
Base (noun)
A number raised to the power of an exponent.
“The logarithm to base 2 of 8 is 3.”
-
Base (noun)
synonym of radix.
-
Base (noun)
The set of sets from which a topology is generated.
-
Base (noun)
A topological space, looked at in relation to one of its covering spaces, fibrations, or bundles.
-
Base (noun)
In hand-to-hand balance, the person who supports the flyer; the person that remains in contact with the ground.
-
Base (noun)
A morpheme (or morphemes) that serves as a basic foundation on which affixes can be attached.
-
Base (noun)
dated form of bass
-
Base (noun)
The smallest kind of cannon.
-
Base (noun)
The housing of a horse.
-
Base (noun)
A kind of skirt (often of velvet or brocade, but sometimes of mailed armour) which hung from the middle to about the knees, or lower.
-
Base (noun)
The lower part of a robe or petticoat.
-
Base (noun)
An apron.
-
Base (noun)
A line in a survey which, being accurately determined in length and position, serves as the origin from which to compute the distances and positions of any points or objects connected with it by a system of triangles.
-
Base (noun)
The game of prisoners’ bars. from 15th c.
-
Base (verb)
To give as its foundation or starting point; to lay the foundation of.
-
Base (verb)
To be located (at a particular place).
-
Base (verb)
To act as a base; to be the person supporting the flyer.
-
Base (adjective)
Low in height; short.
-
Base (adjective)
Low in place or position.
-
Base (adjective)
Of low value or degree.
-
Base (adjective)
Of low social standing or rank; vulgar, common.
-
Base (adjective)
Morally reprehensible, immoral; cowardly.
-
Base (adjective)
Inferior; unworthy, of poor quality.
-
Base (adjective)
Designating those metals which are not classed as precious or noble.
-
Base (adjective)
Alloyed with inferior metal; debased.
“base coin”
“base bullion”
-
Base (adjective)
Of illegitimate birth; bastard.
-
Base (adjective)
Not classical or correct.
“base Latin”
-
Base (adjective)
obsolete form of bass
“the base tone of a violin”
-
Base (adjective)
Not held by honourable service.
“A base estate is one held by services not honourable, or held by villenage. Such a tenure is called base, or low, and the tenant is a base tenant.”
-
Acid (noun)
a substance with particular chemical properties including turning litmus red, neutralizing alkalis, and dissolving some metals; typically, a corrosive or sour-tasting liquid of this kind.
“traces of acid”
“trees were exposed to mixtures of heavy metals, acids, and overdoses of nutrients”
-
Acid (noun)
bitter or cutting remarks or tone of voice
“she was unable to quell the acid in her voice”
-
Acid (noun)
a molecule or other species which can donate a proton or accept an electron pair in reactions.
-
Acid (noun)
the drug LSD
“a bad acid trip”
“she didn’t have a clue the sweet had acid in it”
-
Acid (adjective)
containing acid or having the properties of an acid; having a pH of less than 7.
“acid soils”
-
Acid (adjective)
sharp-tasting or sour
“acid fruit”
-
Acid (adjective)
(of a person’s remarks or tone) bitter or cutting
“she was stung into acid defiance”
-
Acid (adjective)
(of a colour) strikingly intense or bright
“an acid green”
-
Acid (adjective)
(of rock, especially lava) containing a relatively high proportion of silica
“the magma may start off fairly basic and end up at the close of the eruption much more acid”
-
Acid (adjective)
relating to or denoting steel-making processes involving silica-rich refractories and slags
“the acid Bessemer process”
-
Base (noun)
the lowest part or edge of something, especially the part on which it rests or is supported
“she sat down at the base of a tree”
-
Base (noun)
the part of a column between the shaft and pedestal or pavement.
-
Base (noun)
the end at which a part or organ is attached to the trunk or main part
“a shoot is produced at the base of the stem”
-
Base (noun)
a line or surface on which a figure is regarded as standing
“the base of the triangle”
-
Base (noun)
a known line used as a geometrical base for trigonometry.
-
Base (noun)
the lowest part of a shield.
-
Base (noun)
a conceptual structure or entity on which something draws or depends
“the town’s economic base collapsed”
-
Base (noun)
a foundation or starting point for further work
“she uses existing data as the base for the study”
-
Base (noun)
a group of people regarded as supporting an organization, for example by buying its products
“a customer base”
-
Base (noun)
a place used as a centre of operations by the armed forces or others; a headquarters
“he headed back to base”
-
Base (noun)
the main place where a person works or stays
“she makes the studio her base”
“your hotel is a good base from which to explore”
-
Base (noun)
a main or important element or ingredient to which other things are added
“soaps with a vegetable oil base”
-
Base (noun)
a substance into which a pigment is mixed to form paint, such as water, oil, or powdered aluminium hydroxide.
-
Base (noun)
a substance used as a foundation for make-up
“her make-up artist works with base, eye make-up, and lipstick”
-
Base (noun)
a substance capable of reacting with an acid to form a salt and water, or (more broadly) of accepting or neutralizing hydrogen ions.
-
Base (noun)
a purine or pyrimidine group in a nucleotide or nucleic acid.
-
Base (noun)
the middle part of a bipolar transistor, separating the emitter from the collector.
-
Base (noun)
the root or stem of a word or a derivative.
-
Base (noun)
the uninflected form of a verb.
-
Base (noun)
a number used as the basis of a numeration scale.
-
Base (noun)
a number in terms of which other numbers are expressed as logarithms.
-
Base (noun)
each of the four stations that must be reached in turn to score a run.
-
Base (verb)
use (something specified) as the foundation or starting point for something
“entitlement will be based on income”
“the film is based on a novel by Pat Conroy”
-
Base (verb)
situate at a specified place as the centre of operations
“a London-based band”
“the Science Policy Review Unit is based at the University of Sussex”
-
Base (adjective)
without moral principles; ignoble
“the electorate’s baser instincts of greed and selfishness”
-
Base (adjective)
denoting or befitting a person of low social class.
-
Base (adjective)
(of coins or other articles) not made of precious metal
“the basest coins in the purse were made in the 620s AD”