Chemistry Glossary Terms Starting with the Letter P

Chemistry Glossary and Dictionary

P is for periodic table.
P is for periodic table. Alfred Pasieka, Getty Images

This chemistry glossary offers definitions for terms which are commonly used in chemistry and chemical engineering.

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p orbital

pair annihilation

pair production

palladium

para

paraffin

paramagnetism

parent atom

parent nuclide

partial pressure

particulate

particulate matter

parts per billion

parts per million

patent isotope

Pascal (Pa)

passivity

pathogen

patina

Pauli exclusion principle

PBDE - PBDE is an acronym for polybrominated diphenyl ether. PBDE molecules are a class of compounds containing bromine atoms attached to a biphenol ester molecule. The general formula for a PBDE is C12H10-xBrxO where x is an integer between 1 and 10.
Also Known As: polybrominated diphenyl ether
Example: PBDEs are used as flame retardants in many commercial products.

PCB

pentose

peptidase

peptide

peptide bond

percent composition

percent error

percent yield

perchlorate

perfect crystal

perfect vacuum - A perfect vacuum is a volume of space containing no matter.
Also Known As: absolute vacuum

peri- - Peri- is a prefix used in organic chemistry when substituents of a naphthalene occur at the 1 and 8 positions.

periplanar

period

periodic law

periodic table

periodic trend

periodicity

permanganate

permissible exposure limit (PEL)

peroxide

peroxide group

peroxo group

peta

petrochemistry

petroleum

pH

pharmacology

phase

phase boundary

phase change

phase diagram

phase transition

phe

phenol

phenolphthalein

phenyl group

pheromone

philosopher's wool

pH indicator

phlogisticated air - Phlogisticated air was a gas in phlogiston theory that was saturated with phlogiston. Phlogisticated air did not allow the release of phlogiston during combustion.

Phlogisticated air was later identified as the element nitrogen.
Also Known As: nitrogen

phlogiston - Phlogiston was believed to be a substance all combustible matter contained and released when burned. Phlogiston theory was an early chemical theory to explain the process of oxidation. Phlogiston had no odor, taste, color or mass. Deflogisticated substances were called the calx of the substance.

pH meter

phosphate

phospholipid - A phospholipid is a lipid that contains a phosphate group.

phosphatase

phosphorescence

phosphorolysis

phosphorus

phosphorylase

photochemistry

photodecomposition

photoelectric effect

photoelectron - A photoelectron is an electron ejected from an atom due to the collision of a photon. This is the basis of the photoelectric effect.

photon

photosynthesis

physical change

physical chemistry

physical property

physics

phytochemical

phytochemistry

pi bond

pico

piezoelectric

pKa

pKb

Planck's constant

plasma

plasmid

plastic

platinum

plumbum

plutoniumPlutonium is the name for the element with atomic number 94 and is represented by the symbol Pu. It is a member of the actinide group.

pnictogen

pOH

polar bond

polar molecule

polonium

polyamide - A polyamide is a polymer formed by connecting amide monomers by peptide bonds.


Examples: Silk, wool and proteins are all polyamide polymers.

polyatomic ion

polyatomic molecule

polycyclic aromatic hydrocarbon

polydentate

polyester

polymath

polymer

polymerization

polymerize

polymorphism

polynuclear aromatic hydrocarbon

polypeptide

polyphenol - Polyphenols are a type of organic chemical compound found naturally in plants. Polyphenols are groups of phenolic compounds, which are organic ring structures. Polyphenols are categorized according to rings and side groups into four groups: phenolic acids, flavonoids, lignans, and stilbenes.

polyprotic acid

polysaccharide

positron

potash

potassium

potential difference

potential energy

power

PPB

PPM

praseodymium

precipitate

precipitation

precipitation reaction

precision

pressure

pressure relief valve

primary alcohol

primary amide - A primary amide is an amide with one carbon atom bonded to the amide nitrogen atom.

This carbon will be the carbon atom in the carbonyl functional group. Primary amides are often denoted by the shorthand notation of 1° amide.

primary amine - A primary amine is an amine with one carbon atom bonded to the amine nitrogen. Primary amines are often denoted by the shorthand notation 1° Methylamine is an example of a primary amine.

primary carbon - A primary carbon is a carbon atom in a molecule or functional group bonded to one and only one other carbon. Primary carbon is often denoted as 1° carbon.

primary standard

principal energy level

principal quantum number

principal species

prion

pro

product

proenzyme

promethium

proof

property

propogation reaction

protactinium

protease

protein

protiation

protide

protio group

protium

proton

protonation

proton emission - Proton emission is a type of radioactive decay where an atom's nucleus ejects a proton. Proton emission is commonly abbreviated by a lower case p.
Also Known As: proton radiation
Example: The isotope of fluorine fluorine-15 decays by proton emission into oxygen-14.

PSI

psi (Ψ)

p-type semiconductor

pure substance

pyramidal

pyrophoric

pyrometallurgy

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