ELEMENTS

ELEMENT BRIEF

Name, description, source environment, prominent features, amalgamation, reactivity, and characteristics of the isolated element.

SYNTAX: X?

DISCOVERY

Accepted year of use and record.

SYNTAX: 0 XX (AD or BC)

ETYMOLOGY

Origin of chemical element name, language and translation.

SYNTAX: (language, subject and translation) or (Person) or (Place) or (Entity).

ELEMENT

Historically, atomic element names are derived from people, places, mythology, minerals, astronomical objects and at times temporarily defined.

SYNTAX: X?

SYMBOL

Abbreviation of the atomic element name.

SYNTAX: X?

ATOMIC NUMBER

The atomic element number, known also as the proton number (symbol Z), defines the number of protons within the nucleus of an atom, and is also equal to the number of electrons within this uncharged atom.

SYNTAX: ##0

CAS NUMBER

The Chemical Abstracts Service (CAS) number is an identifier that denotes individual chemical substance descriptions that include all chemical elements, isotopes, alloys, minerals, organic and inorganic compounds.

SYNTAX: 0-??-?

ELEMENTAL SPECTRUM

The emission spectra of the atomic elements are made apparent by spectroscopy, the study of electromagnetic radiation interactions with matter, that highlight the specific emissions that are amplified and displayed as a collective spectrum of electromagnetic radiation frequencies, emitted by the many possible electron transitions and specific energy differences for specific atom types.

SYNTAX: (emission spectral lines)

ELEMENTAL COLOUR

Apparent representation and accepted colour.

SYNTAX: Xx

REFRACTIVE INDEX

Comparative ratio defining how fast light propagates through a material. The divergence of a ray of light from the incoming path, angle of incidence, i, through the normal (medium), to the angle of refraction, r. The refractive index, n is expressed as the defined ratio of the sine of the angle of incidence (sin i), to the sine of the angle of refraction (sin r), 'n = sin i / sin r' which is also equal to the velocity of light c of a given wavelength in empty space, divided by velocity v in a substance, 'n = c/v'.

SYNTAX: 0.000'000

POISSON RATIO

The measure of the Poisson effect, the Poisson ratio, ν, is the expansion of material in directions perpendicular to the direction of compression or when stretched, contract transverse to the direction of stretching.

SYNTAX: 0.000

MOLAR VOLUME

The volume occupied by one mole of substance at an established temperature and pressure is the molar volume Vm and is equal to the molar mass M, divided by mass density ρ and is expressed as cm³ per mole.

SYNTAX: 0.000 cm³

HARDNESS: BRINELL

Measure of the Brinell scale, is by defining the hardness of materials through indentation and measure by scale. Based on a 10mm indenter steel or carbide ball with an applied load of 3,000 kilogram-force and is expressed in Pascals.

SYNTAX: 0.00 Pa, 0.000'0 Atm

HARDNESS: MOHS

Measure of the Mohs scale, is a qualitative scratch resistance of minerals, by using ten minerals as a comparative scratch test of softer to harder materials: (1) Talc, (2) Gypsum, (3) Calcite, (4) Fluorite, (5) Apatite, (6) Orthoclase, (7) Quartz, (8) Topaz, (9) Corundum, (10) Diamond.

SYNTAX: #0.00

HARDNESS: VICKERS

Measure of the Vickers scale, is by defining the hardness of materials through indentation. The Diamond Pyramid Hardness DPH, is based on a pyramidal diamond indenter giving each face 22° per side to the horizontal plane.

SYNTAX: 0.00 Pa, 0.000'0 Atm

SPEED OF SOUND

The distance that a sound wave travels per iteration of time through an elemental medium is the speed of sound. In air this approaches 343 m/s, 1,480 m/s in water, 5,120 m/s in iron and 12,000 m/s in diamond. Expressed in m/s then converted into the Mach number, the ratio of flow velocity past a boundary, to the local speed of sound. At Mach 1, the local flow velocity is equal to the speed of sound.

SYNTAX: 0 m/s, Mach 0.000'0

MODULUS: BULK

Measure of how resistive to compression a substance is, as the ratio of the pressure increase is to the resulting relative decrease of the volume.

SYNTAX: 0.00 Pa, 0.000'0 Atm

MODULUS: SHEAR

Measure of how rigid a substance is, by the deformation of a solid when it experiences a force parallel to one of its surfaces, whilst the opposite face experiences an opposing force, such as friction. To note, a fluid has a zero shear modulus.

SYNTAX: 0.00 Pa, 0.000'0 Atm

MODULUS: YOUNG

Measure of how stiff a substance is, by stress (force per unit area) and strain (proportional deformation) within a material of uniaxial deformation.

SYNTAX: 0.00 Pa, 0.000'0 Atm

ALLOTROPES

Allotropy is the property of individual chemical elements to exist in more than one form by possessing a differing bond structure. To illustrate; carbon atoms are bonded together in a tetrahedral lattice arrangement for diamond, hexagonal lattice for graphite and spherical or tubular configurations for fullerenes.

SYNTAX: (name in full) or (name as symbol)

MELTING POINT

Measure of the temperature moment a substance changes phase from solid to liquid and is dependent upon atmospheric and environmental pressure.

SYNTAX: 0.00 K, 0.00 °C

BOILING POINT

Measure of the temperature moment of which the vapor pressure of the liquid equals the pressure surrounding the liquid, then changes into a vapor.

SYNTAX: 0.00 K, 0.00 °C

AUTOMATIC IGNITION

Measure of the lowest temperature moment of which an element spontaneously ignites in an atmosphere without an external ignition source.

SYNTAX: 0.00 K, 0.00 °C

FLASHPOINT

Measure of the lowest temperature moment of which an elemental vapour ignites in an atmosphere with an external ignition source.

SYNTAX: 0.00 K, 0.00 °C

CRITICAL TEMPERATURE

Measure of the critical temperature end point of a phase equilibrium curve and is the highest temperature of which vapor and liquid fluid phases coexist.

SYNTAX: 0.00 K, 0.00 °C

CRITICAL PRESSURE

Measure of the critical pressure end point of a phase equilibrium curve and is the highest pressure of which vapor and liquid fluid phases coexist.

SYNTAX: 0.00 Pa, 0 Atm

THERMAL CONDUCTIVITY

Measure of heat conduction of a substance within a tensor, a measurable vector space. Materials of low thermal conductivity, transfer heat at a lower rate (thermal insulator) to materials of high thermal conductivity (heat sink).

SYNTAX: 0.000'000 W/(m K)

THERMAL EXPANSION

Measure of change in shape, area and volume of a substance in response to temperature change. When a substance is heated, kinetic energy increases to maintain a greater average separation. If the crystalline solid is isometric (balanced structure), the expansion will be uniform to the crystal dimensions.

SYNTAX: 0.000'000'0 K⁻¹

SPECIFIC HEAT

Measure of thermal capacity and is the amount of heat required to raise the temperature of one kilogram of mass by 1 kelvin.

SYNTAX: 0.00 J/(kg K)

HEAT FUSION

The enthalpy of fusion of a substance, is the change in enthalpy (internal energy of a system) resulting from providing heat, to a substance to change its state from a solid to a liquid, at constant pressure and includes the energy required to allow for change in volume by displacing its environment against ambient pressure.

SYNTAX: 0.000 kJ/mol

HEAT VAPORISATION

Measure of the enthalpy of vaporisation of a substance by identifying the heat energy that is required to be added to a liquid substance, to transform into a gas.

SYNTAX: 0.000 kJ/mol

HEAT COMBUSTION

Measure of amount of energy released as heat with one mole of substance and is an exothermic process that combusts with oxygen to release energy.

SYNTAX: 0.00 J/(kg K)

CURIE POINT

Measure of temperature above which materials lose their permanent magnetic properties. Magnetism is determined by the magnetic dipole moment within an atom which originates from angular momentum and electron spin.

SYNTAX: 0.00 K, 0.00 °C

NÉEL POINT

Measure of temperature above which antiferromagnetic materials (adjacent ions behave as magnets and align at low temperatures into an opposing alignment) becomes paramagnetic (weakly attracted by an externally applied magnetic field).

SYNTAX: 0.00 K, 0.00 °C

ADIABATIC INDEX

Known as the heat capacity ratio or the isentropic expansion factor and is the ratio of the heat capacity at constant pressure (CP) to heat capacity at constant volume (CV).

SYNTAX: 0/0

PHASE

State of thermodynamic space whereby all physical properties of an element are chemically uniform, physically distinct and at equilibrium.

SYNTAX: (solid) or (liquid) or (gas)

ELECTRICAL TYPE

There are three main classes of electrical properties for an element; conductors that permit the flow of an electrical current, to insulators that possess resistance and prevent the flow of electrical current, to semiconductors that have differing reactions to either conduction or resistance.

SYNTAX: (Conductor) or (Insulator) or (Semiconductor)

CONDUCTIVITY

Electrical conductivity, σ (sigma), is the inverse of electrical resistivity and is the ability of a material to conduct an electric current.

SYNTAX: 0.00 S/m

RESISTIVITY

Electrical resistivity, ρ (rho), is the inverse of electrical conductivity and is the ability of a material to resist an electric current.

SYNTAX: 0.00 Ω·m

SUPERCONDUCTING POINT

Electrical resistivity, ρ (rho), is the inverse of electrical conductivity and is the ability of a material to resist an electric current.

SYNTAX: 0.000 K

MAGNETIC TYPE

Diamagnetism is present in all elements and is the material property that opposes a magnetic field and when in the presence of other magnetism forms, this magnetism force ceases. Paramagnetism benefits from unpaired electrons and is unrestricted to align its magnetic moment in any direction and when attracted to an externally applied magnetic field, a corresponding magnetic field is created. Ferromagnetism benefits from unpaired electrons and parallel an applied field, magnetic moments orient these magnets parallel to each other to maintain a lowered-energy state, whereas Antiferromagnetism retains magnetism without an applied field.

SYNTAX: (Antiferromagnetic) (Ferromagnetic) (Diamagnetic) or (Paramagnetic)

MASS SUSCEPTIBILITY

Measure of how materials become magnetised in an applied magnetic field, ratio of magnetisation M, to the intensity of the applied magnetising field H. Paramagnetism is the alignment with the magnetic field as diamagnetism is against.

SYNTAX: 0.000'000'000'0

MOLAR SUSCEPTIBILITY

Measure of the molar magnetic susceptibility χm, is the product of the mass susceptibility and molar volume per magnetism type.

SYNTAX: 0.000'000'000'000'00

VOLUME SUSCEPTIBILITY

The magnetisation of an element is a product of the magnetic field strength and volume magnetic susceptibility.

SYNTAX: 0.000'000'000'00

CLASSIFICATION

NON METAL

Chemical elements that lack metallic attributes, have high ionisation energies, electron affinity and electronegativity values, low melting and boiling points and are poor conductors of heat and electricity.

NOBLE GAS

Chemical elements that lack non-metallic attributes, are odourless, colourless, monatomic gases with very low chemical reactivity. The outer shell of valence electrons are complete and give rise to minimal participation in chemical reactions and have melting and boiling points that span within 10 °C.

ALKALI METAL

All alkali metals occur in nature as their compounds, with major biological roles as electrolytes, are soft, shiny, highly reactive and readily lose their outermost electron to form cations, ions with a charge of +1.

ALKALINE EARTH

Most alkaline earth metals are primordial elements except for radium, which occurs through the decay chain of uranium and thorium, are shiny, silvery-white, reactive and readily lose their outermost electrons to form cations, ions with a charge of +2.

METALLOID

Chemical element with metal and non-metal properties that are brittle with a metallic appearance and are fair conductors of electricity. Chemically, they behave as non-metals as their compounds are used to form alloys, catalysts, biological agents, flame retardants and semiconductors.

HALOGEN

As halogens react with metals, differing salts are produced, calcium fluoride, sodium chloride (table salt), silver bromide and potassium iodide. All halogens that are bonded to hydrogen form acids, whereas middle halogens, chlorine, bromine and iodine, are used as disinfectants, with organobromides that are a class of flame retardants.

BASIC METAL

Materials with strength, are malleable and ductile, with a lustrous appearance and a high conduction of electricity and heat. Metal atoms are predisposed to losing their outer shell of electrons to the attractive force behind the electrons arising from interactions between atoms of solid or liquid metal, a metallic bond.

TRANSITION METAL

Element that is metallic, with atoms that have or give rise to an atom with a partially populated d sub-shell.

LANTHANIDE

15 metallic chemical elements, Lanthanum to lutetium form trivalent cations, ions with a charge of +3. Lanthanides, with scandium and yttrium form the rare earth elements.

ACTINIDE

15 metallic chemical elements, Actinium to lawrencium. All actinides are radioactive, releasing energy through radioactive decay. Primordial elements uranium and thorium with synthetic plutonium are the most abundant and are used in nuclear reactors and weapons, whereas americium is used in the ionisation chambers of smoke detectors. The decay chain of uranium produces actinium, protactinium, neptunium and plutonium (also produced from transmutation reactions in uranium ores).

ATOMIC WEIGHT

The standard atomic weight Ar, of a chemical element, is based upon averaging the individual weights of stable and unstable isotopes of that elemental material.
The number of atoms in a mole, the Avogadro's number, has 6.022'140'76 × 1023 Atoms, which is equal to 12 grams of the carbon isotope C-12, is 1.992'646'88 × 10-23 g per C-12 carbon atom.

SYNTAX: 0.000'000'0

ELECTRON CONFIGURATION

Notation for the distribution of electrons within an atom or molecule in atomic or molecular orbitals with descriptive configurations that describe each electron as moving independently in an orbital of orbitals.

SYNTAX: [X?] 0a (Sup 0) #? (Sup #) #? (Sup #) #? (Sup #) #? (Sup #)

ATOMIC RADIUS

Central from the nucleus to the outer boundary of a surrounding cloud of electrons is the measure of the radius of an atom.

SYNTAX: 0 pm

COVALENT RADIUS

Single, double and triple bonds each have two covalent radii, equal in length to the covalent bond between two atoms. On average, this distance is measured value in picometres, pm or angstroms, Å (100 pm) by X-ray diffraction, rotational spectroscopy or by neutron diffraction on molecular crystals.

SYNTAX: 0 pm

VAN DER WAALS RADIUS

Measure of the radius of an effective volume that denotes the closest approach to another atom. This range is defined by the chemical environment and are determined from the mechanical properties of gases, the measurements of unbonded atoms in crystals or from the measure of electrical or optical properties.

SYNTAX: 0 pm

CRYSTAL STRUCTURE

Elemental solids have three-dimensional geometrical shapes that are known as crystalline solids with an orderly arrangements of atoms known as a crystal lattice. There are seven lattice systems: Triclinic (TRI), Monoclinic (MON), Orthorhombic (ORT), Rhombohedral (RHO), Tetragonal (TET), Hexagonal (HEX) and Cubic (CUB) with fourteen differing crystal lattices, known as the Bravais Lattices: Primitive (PRI), Base-centred (BAC), Face-centred (FAC) and Body-centred (BOC). Variations include Single Close Packed (CP1), Double Close Packed (CP2) or Diamond (DIA):

Lattice System
( Axial Length ) ( Axial Angle )
Bravais or Specific Variation

TRI
( a ≠ b ≠ c ) ( α ≠ β ≠ γ ≠ 90° )
PRI

MON
( a ≠ b ≠ c ) ( a ≠ 90°, β = γ = 90° )
PRI, BAC

ORT
( a ≠ b ≠ c ) ( α = β = γ = 90° )
PRI, BAC, BOC, FAC

RHO
( a = b = c ) ( α = β = γ ≠ 90° )
PRI

TET
( a = b ≠ c ) ( α = β = γ = 90° )
PRI, BOC

HEX
( a = b ≠ c ) ( α = β = 90°, γ = 120° )
PRI, CP1, CP2

CUB
( a = b = c ) ( α = β = γ = 90° )
PRI, BOC, FAC, DIA

SYNTAX: (Lattice System) - (Bravais Variation) or (Specific Variation)

DENSITY

The volumetric mass density of a substance is dependent upon temperature and pressure and is defined as the mass per unit volume of a solid, liquid or gas.

SYNTAX: 0.000'00 g/cm³

SPACE GROUP NAME

In three dimensions, there are 230 crystallographic space groups, each known by their international short symbol.

SYNTAX: (Hermann–Mauguin 'short name' notation)

SPACE GROUP NUMBER

The identities for all crystallographic space groups that are recorded within a register and are referenced with a numeric identifier.

SYNTAX: ##0

LATTICE ANGLES

Angular dimensions within a crystal lattice with notation of α (alpha), β (beta) and γ (gamma); an α and γ (when α and β are equal) or an α (when all are equal).

SYNTAX: (α, β, γ)

LATTICE CONSTANTS

Physical dimensions in length of unit cells within a crystal lattice with notation of a, b and c; an a and c (when a and b are equal) or an a (when all are equal).

SYNTAX: (a, b, c)

VALENCE

Measure of the amalgamated energy of atoms when combining to form chemical compounds or molecules and is the maximum number of univalent atoms that combine with an atom of an element under consideration.

SYNTAX: 0

ELECTRONEGATIVITY

Chemical property, describing the capability of an atom to attract shared electron pairs to itself and is the result of its atomic number and what distance valence electrons are from their charged nucleus. The higher the electronegativity, χ value, the more an atom or substituent group will attract electrons towards itself, as opposed to the donation of electrons with electropositivity.

SYNTAX: 0.00

ELECTRON AFFINITY

Charge-transfer reaction, revealing the amount of energy released as an electron is added to a neutral atom or molecule in the gaseous state to form a negative ion. Negative affinities are where electron capture requires energy by impinging an electron has a kinetic energy large enough to excite a resonance of the atom-plus-electron system.

SYNTAX: 0.00 kJ/mol

HALF-LIFE

Half the time period that defines the life of an element experiencing probabilistic radioactive decay, constant over the lifetime of an exponentially decaying quantity, that is a function of the number of half-lives elapsed. An element that expends a single half-life will result in a single half-life remaining, whereas for 2 or more half-lives, the remaining half-life per iteration is halved again, 2 half-lives for a quarter-life, 3 half-lives for an eighth-life...

SYNTAX: ‘Stable’ or ‘Unstable’, 0 (time)

LIFETIME

The life of all atoms are determined by the universal forces within, as with the stability of the nucleus of protons and neutrons, defined by the ‘strong nuclear force’, the stability of electrons surrounding the nucleus, the ‘weak nuclear force’ and external forces. Atoms that emit no emissions are ‘stable’, whereas ‘unstable’ atoms release energy by augmenting particles within the nucleus or by decay processes that produce heat and energy distributed to a larger number of quantum states, that result in a singular or avalanche of gamma-ray decay events, emitting alpha, beta and gamma rays, transmuting into decay products that form part of a decay chain, resulting in atoms of lower atomic masses and constituent atomic components.

SYNTAX: ‘Stable’ or ‘Unstable’, 0 (time)

QUANTUM NUMBERS

Characteristics of electrons within an atom, the specific shells, subshells, orbitals, and spins of electrons, represented by four quantum numbers.

SYNTAX: (n, ℓ, m_ℓ and m_s)

The ‘principal quantum number’, n, defines a specific electron shell that is occupied by a particular electron within an atom, one of seven electron shells that are defined as 1 being ‘k’, 2 ‘l’, 3 ‘m’, 4 ‘n’, 5 ‘o’, 6 ‘p’ and 7 as ‘q’. Each shell possessing a rest state of of n=1, establishing differing measured distances that the electron orbital is away from the nucleus, subsequently increasing as electrons absorbs energy or alternatively decreasing to the lower limit at rest, as photons are emitted.

SYNTAX: (1 ≤ n)

The ‘azimuthal (angular momentum) quantum number’, ℓ, determines the shape of the electron orbital and magnitude of the orbital angular momentum. When stated, ℓ = 0 is an ‘s’ orbital of spherical shape, ℓ = 1 is a ‘p’ orbital of two ellipsoid halves, ℓ = 2 is a ‘d’ orbital of two tear drops separated by a toroidal object and ℓ = 3 is an ‘f’ orbital of two tear drops that are separated by two toroidal objects.

SYNTAX: (0 ≤ ℓ ≤ n - 1)

The ‘magnetic quantum number’, mℓ, describes the orientation of the electron orbital cloud, ranging in value from -ℓ to ℓ, yielding the projection of the orbital angular momentum along a specified axis. The capacity of orbital ‘s’, has 1 orbital (0) with 2 electrons per subshell, orbital ‘p’, has 3 angular momentum vectors, -1, 0 and 1, with 6 electrons per subshell, orbital ‘d’, has 5 angular momentum vectors, -2, -1, 0, 1 and 2, with 10 electrons per subshell, orbital ‘f’, has 7 angular momentum vectors, -3, -2, -1, 0, 1, 2 and 3, with 14 electrons per subshell, whereas orbital ‘g’, has 9 angular momentum vectors, -4, -3, -2, -1, 0, 1, 2, 3 and 4, with 18 electrons per subshell.

SYNTAX: (-ℓ ≤ m_ℓ ≤ ℓ)

The spin quantum number, m_s, describes the intrinsic angular momentum of an electron in an atom, the spin, ranging in value from -s to s, yielding ‘-½’ as ‘spin down’ and ‘½’ as ‘spin up’ states. An orbital will never contain more than two electrons, with each electron in any individual orbital, possessing a different quantum number.

SYNTAX: (-s ≤ m_s ≤ s)

There are four rules that govern how electrons fill orbitals, the first, the ‘Pauli Exclusion Principle’ states that an orbital my only contain a maximum of two electrons of opposing spin. The second, the ‘Aufbau or Build-up Principle’ state that electrons will fill lower energy orbitals prior to higher energy orbitals. The third, ‘Hund's Rule’ states that when there are orbitals of equal energy available, electrons will enter orbitals in succession, to maximise degeneracy and at a point whereby half of the available orbitals are filled, will pairing-up occur. The fourth, ‘Madelung's Rule’ states that orbitals will fill with electrons as ‘n + ℓ’, ‘n’ the ‘principal quantum number’ and ‘ℓ’ as the ‘azimuthal quantum number’ and when there are identical values of ‘n + ℓ’, energy increases with increasing ‘n’.

NEUTRON CROSS SECTION

Defined area on the surface of an atom, that is the window of scattered interactions between one or more incident neutrons and the target nucleus.

SYNTAX: 0.000'00 b σ_s

NEUTRON MASS ABSORPTION

Defined area on the surface of an atom, that is the window of interactions whereby one or more incident neutrons impact and merge with the target nucleus.

SYNTAX: 0.000'00 b σ_a

IONISATION ENERGIES

Ionisation potential of one or many specific energy targets required to remove a bound electron, a valence electron, from an atom.

SYNTAX: 0 'Ionisation Energies'

ALLOTROPES

Property of specific chemical elements to exist in the same solid, liquid or gas states with differing structural forms.

SYNTAX: 0 'Allotropes'

ISOTOPES

Stable and unstable atoms that possess the same number of protons with a different number of neutrons to their respective chemical element.

SYNTAX: 0 ‘Stable’ or ‘Unstable’ Isotopes