element
(chemical element)
(class of atom based on its number of protons)
The chemistry term element (chemical element) consists of all
material that cannot be (chemically) changed or broken down into other
materials.
Such an element consists of all atoms with some given
number of protons, i.e., all atoms with 10 protons comprise one
particular element and those with 11 comprise another.
Currently, 118 elements have been discovered or created.
The proton count is termed its atomic number (Z).
Two atoms may be of the same element even if their
number of neutrons differs, in which case they are
termed different isotopes of the same element.
The total number of nucleons (protons and neutrons in the atomic
nucleus) is termed the mass number (or atomic mass number),
so two isotopes of the same element will have the same
atomic number but differ in mass numbers.
The term atomic weight (or relative atomic mass)
is the average mass per atom in daltons
(1/12 the mass of carbon with mass number 12, i.e., of carbon-12)
in a sample of the element. (Atomic weight is the
traditional term but the latter term is more reasonable
since it is a measure of mass rather than weight.)
The atomic weight reflects the relative
abundances of the isotopes in the sample.
The term standard atomic weight is used for the
known atomic weight of an element as found on Earth,
i.e., reflecting such abundances on Earth.
Example elements:
Name | Symbol | Atomic Number |
hydrogen | H | 1 |
helium | He | 2 |
lithium | Li | 3 |
beryllium | Be | 4 |
boron | B | 5 |
carbon | C | 6 |
nitrogen | N | 7 |
oxygen | O | 8 |
fluorine | F | 9 |
neon | Ne | 10 |
sodium | Na | 11 |
magnesium | Mg | 12 |
aluminum | Al | 13 |
silicon | Si | 14 |
phosphorus | P | 15 |
sulfur | S | 16 |
chlorine | Cl | 17 |
argon | Ar | 18 |
potassium | K | 19 |
calcium | Ca | 20 |
scandium | Sc | 21 |
titanium | Ti | 22 |
vanadium | V | 23 |
chromium | Cr | 24 |
manganese | Mn | 25 |
iron | Fe | 26 |
cobalt | Co | 27 |
nickel | Ni | 28 |
copper | Cu | 29 |
zinc | Zn | 30 |
germanium | Ge | 32 |
strontium | Sr | 38 |
zirconium | Zr | 40 |
technetium | Tc | 43 |
silver | Ag | 47 |
tellurium | Te | 52 |
xenon | Xe | 54 |
cesium | Cs | 55 |
barium | Ba | 56 |
lanthanum | La | 57 |
praseodymium | Pr | 59 |
neodymium | Nd | 60 |
europium | Eu | 63 |
iridium | Ir | 77 |
platinum | Pt | 78 |
gold | Au | 79 |
mercury | Hg | 80 |
thallium | Tl | 81 |
lead | Pb | 82 |
bismuth | Bi | 83 |
radium | Ra | 88 |
actinium | Ac | 89 |
thorium | Th | 90 |
uranium | U | 92 |
plutonium | Pu | 94 |
(physics,chemistry)
Further reading:
https://en.wikipedia.org/wiki/Chemical_element
https://en.wikipedia.org/wiki/List_of_chemical_elements
https://www.thoughtco.com/what-is-a-chemical-element-604297
https://www.oxfordreference.com/display/10.1093/oi/authority.20110803095605316
https://www.windows2universe.org/physical_science/element.html
https://www.chemeurope.com/en/encyclopedia/Chemical_element.html
Referenced by pages:
absorption line
abundances
alpha element
alpha process (α process)
alpha-enhanced
aluminum (Al)
astrobiology
atomic number (Z)
Avogadro's number (NA)
barium star (Ba star)
Big Bang nucleosynthesis (BBN)
bracket notation
calcium (Ca)
carbon (C)
carbon burning
chemical equilibrium (CE)
Compton reflection
cosmic dust
cosmic neutrino background (CNB)
Cryogenic Dark Matter Search (CDMS)
double-line spectroscopic binary (SB2)
electron capture
electron shell
emission line
equilibrium condensation model
fine structure
fusion
globular cluster (GC)
GW170817
helium (He)
HI region (HI)
Honda-like star
hydrocarbon (HC)
hydrogen (H)
hydrogen cyanide (HCN)
ice giant
ionization correction factor (ICF)
iron (Fe)
iron peak
iron peak element
isotope
Lambda Boötis star (λ Boo)
lanthanide (Ln)
light curve
lithium (Li)
lithium depletion boundary (LDB)
Lyman series (L)
magnesium (Mg)
mass fraction
mass number (A)
metal
metallic hydrogen
metallicity (Z)
mole (mol)
molecular handedness
neon (Ne)
neutron rich
neutron scattering
neutron spectrometer
nickel (Ni)
nitrogen (N)
nuclear statistical equilibrium (NSE)
nucleosynthesis
nuclide
oxidation state
oxygen (O)
phosphorus (P)
photoionization
post-main-sequence star
potassium/thorium ratio (K/Th ratio)
proton
r-process
radioactive dating
radioactive decay
radioactivity
radiolysis
reducing atmosphere
refractory material
rocky planet
Rydberg constant (RH)
s-process
sedimentation
self-absorption
sensitivity function (S)
siderophile
silicon (Si)
silicon burning
SMSS J2003-1142
sodium (Na)
Solar and Heliospheric Observatory (SOHO)
spectral line
spectral line designation
spectral line energy distribution (SLED)
spectral type
stellar age determination
stellar model atmosphere
sulfur (S)
supernova light curve (SN light curve)
surface abundance
technetium star
titanium (Ti)
trans-iron element
transition region
Type Ia supernova
valley of beta stability
volatile material
Z+
ZEPLIN
Index