Periodic Table Element Comparison: Compare Elements - Arsenic vs Selenium
Compare Arsenic and Selenium on the basis of their properties, attributes and periodic table facts. Compare elements on more than 90 properties. All the elements of similar categories show a lot of similarities and differences in their chemical, atomic, physical properties and uses. These similarities and dissimilarities should be known while we study periodic table elements. You can study the detailed comparison between Arsenic vs Selenium with most reliable information about their properties, attributes, facts, uses etc. You can compare As vs Se on more than 90 properties like electronegativity , oxidation state, atomic shells, orbital structure, Electronaffinity, physical states, electrical conductivity and many more. Arsenic and Selenium comparison table on more than 90 properties.
Arsenic and Selenium Comparison
Facts
| Name | Arsenic | Selenium |
|---|---|---|
| Atomic Number | 33 | 34 |
| Atomic Symbol | As | Se |
| Atomic Weight | 74.9216 | 78.96 |
| Phase at STP | Solid | Solid |
| Color | Silver | Gray |
| Metallic Classification | Metalloid | Other Nonmetal |
| Group in Periodic Table | group 15 | group 16 |
| Group Name | nitrogen family | oxygen family |
| Period in Periodic Table | period 4 | period 4 |
| Block in Periodic Table | p -block | p -block |
| Electronic Configuration | [Ar] 3d10 4s2 4p3 | [Ar] 3d10 4s2 4p4 |
| Electronic Shell Structure (Electrons per shell) | 2, 8, 18, 5 | 2, 8, 18, 6 |
| Melting Point | 1090 K | 494 K |
| Boiling Point | 887 K | 958 K |
| CAS Number | CAS7440-38-2 | CAS7782-49-2 |
| Neighborhood Elements | Neighborhood Elements of Arsenic | Neighborhood Elements of Selenium |
History
| Parameter | Arsenic | Selenium |
|---|---|---|
| History | The element Arsenic was discovered by Arabic alchemist in year ca. 800 AD. Arsenic derived its name English word (Latin arsenicum). | The element Selenium was discovered by J. Berzelius and G. Gahn in year 1817 in Sweden. Selenium derived its name from the Greek selene, meaning 'moon'. |
| Discovery | Arabic alchemist (ca. 800 AD) | J. Berzelius and G. Gahn (1817) |
| Isolated | () | J. Berzelius and G. Gahn (1817) |
Presence: Abundance in Nature and Around Us
Parts per billion (ppb) by weight / by atoms (1ppb =10^-7 %)
| Property | Arsenic | Selenium |
|---|---|---|
| Abundance in Universe | 8 / 0.1 | 30 / 0.5 |
| Abundance in Sun | - / - | - / - |
| Abundance in Meteorites | 1800 / 460 | 13000 / 2900 |
| Abundance in Earth's Crust | 2100 / 580 | 50 / 10 |
| Abundance in Oceans | 2.3 / 0.19 | 0.45 / 0.035 |
| Abundance in Humans | 50 / 4 | 50 / 4 |
Crystal Structure and Atomic Structure
| Property | Arsenic | Selenium |
|---|---|---|
| Atomic Volume | 12.95 cm3/mol | 16.385 cm3/mol |
| Atomic Radius | 114 pm | 103 pm |
| Covalent Radius | 119 pm | 116 pm |
| Van der Waals Radius | 185 pm | 190 pm |
Atomic Spectrum - Spectral Lines | ||
| Emission Spectrum |  |  |
| Absorption Spectrum |  |  |
| Lattice Constant | 375.98, 375.98, 1054.75 pm | 905.4, 908.3, 1160.1 pm |
| Lattice Angle | π/2, π/2, 2 π/3 | π/2, 1.58493, π/2 |
| Space Group Name | R_ 3m | P121/c1 |
| Space Group Number | 166 | 14 |
| Crystal Structure | Simple Trigonal  | Simple Monoclinic  |
Atomic and Orbital Properties
| Property | Arsenic | Selenium |
|---|---|---|
| Atomic Number | 33 | 34 |
| Number of Electrons (with no charge) | 33 | 34 |
| Number of Protons | 33 | 34 |
| Mass Number | 74.9216 | 78.96 |
| Number of Neutrons | 42 | 45 |
| Shell structure (Electrons per energy level) | 2, 8, 18, 5 | 2, 8, 18, 6 |
| Electron Configuration | [Ar] 3d10 4s2 4p3 | [Ar] 3d10 4s2 4p4 |
| Valence Electrons | 4s2 4p3 | 4s2 4p4 |
| Oxidation State | -3, 3, 5 | -2, 2, 4, 6 |
| Atomic Term Symbol (Quantum Numbers) | 4S3/2 | 3P2 |
| Shell structure |  |  |
Isotopes and Nuclear Properties
Arsenic has 1 stable naturally occuring isotopes while Selenium has 5 stable naturally occuring isotopes.
| Parameter | Arsenic | Selenium |
|---|---|---|
| Known Isotopes | 60As, 61As, 62As, 63As, 64As, 65As, 66As, 67As, 68As, 69As, 70As, 71As, 72As, 73As, 74As, 75As, 76As, 77As, 78As, 79As, 80As, 81As, 82As, 83As, 84As, 85As, 86As, 87As, 88As, 89As, 90As, 91As, 92As | 65Se, 66Se, 67Se, 68Se, 69Se, 70Se, 71Se, 72Se, 73Se, 74Se, 75Se, 76Se, 77Se, 78Se, 79Se, 80Se, 81Se, 82Se, 83Se, 84Se, 85Se, 86Se, 87Se, 88Se, 89Se, 90Se, 91Se, 92Se, 93Se, 94Se |
| Stable Isotopes | Naturally occurring stable isotopes: 75As | Naturally occurring stable isotopes: 74Se, 76Se, 77Se, 78Se, 80Se |
| Neutron Cross Section | 4.3 | 11.7 |
| Neutron Mass Absorption | 0.002 | 0.0056 |
Chemical Properties: Ionization Energies and electron affinity
| Property | Arsenic | Selenium |
|---|---|---|
| Valence or Valency | 5 | 6 |
| Electronegativity | 2.18 Pauling Scale | 2.55 Pauling Scale |
| Electron Affinity | 78 kJ/mol | 195 kJ/mol |
| Ionization Energies | 1st: 947 kJ/mol 2nd: 1798 kJ/mol 3rd: 2735 kJ/mol 4th: 4837 kJ/mol 5th: 6043 kJ/mol 6th: 12310 kJ/mol | 1st: 941 kJ/mol 2nd: 2045 kJ/mol 3rd: 2973.7 kJ/mol 4th: 4144 kJ/mol 5th: 6590 kJ/mol 6th: 7880 kJ/mol 7th: 14990 kJ/mol |
Physical Properties
| Property | Arsenic | Selenium |
|---|---|---|
| Density | 5.727 g/cm3 | 4.819 g/cm3 |
| Molar Volume | 12.95 cm3/mol | 16.385 cm3/mol |
Elastic Properties | ||
| Young Modulus | 8 | 10 |
| Shear Modulus | - | 3.7 GPa |
| Bulk Modulus | 22 GPa | 8.3 GPa |
| Poisson Ratio | - | 0.33 |
Hardness - Tests to Measure of Hardness of Element | ||
| Mohs Hardness | 3.5 MPa | 2 MPa |
| Vickers Hardness | - | - |
| Brinell Hardness | 1440 MPa | 736 MPa |
Electrical Properties | ||
| Electrical Conductivity | 3300000 S/m | - |
| Resistivity | 3e-7 m Ω | - |
| Superconducting Point | - | - |
Heat and Conduction Properties | ||
| Thermal Conductivity | 50 W/(m K) | 0.52 W/(m K) |
| Thermal Expansion | - | - |
Magnetic Properties | ||
| Magnetic Type | Diamagnetic | Diamagnetic |
| Curie Point | - | - |
| Mass Magnetic Susceptibility | -3.9e-9 m3/kg | -4e-9 m3/kg |
| Molar Magnetic Susceptibility | -2.92e-10 m3/mol | -3.16e-10 m3/mol |
| Volume Magnetic Susceptibility | -0.0000223 | -0.0000193 |
Optical Properties | ||
| Refractive Index | 1.001552 | 1.000895 |
Acoustic Properties | ||
| Speed of Sound | - | 3350 m/s |
Thermal Properties - Enthalpies and thermodynamics
| Property | Arsenic | Selenium |
|---|---|---|
| Melting Point | 1090 K | 494 K |
| Boiling Point | 887 K | 958 K |
| Critical Temperature | - | 1766 K |
| Superconducting Point | - | - |
Enthalpies | ||
| Heat of Fusion | 27.7 kJ/mol | 5.4 kJ/mol |
| Heat of Vaporization | 32.4 kJ/mol | 26 kJ/mol |
| Heat of Combustion | - | - |
Regulatory and Health - Health and Safety Parameters and Guidelines
| Parameter | Arsenic | Selenium |
|---|---|---|
| CAS Number | CAS7440-38-2 | CAS7782-49-2 |
| RTECS Number | {N/A, RTECSCG0525000, N/A} | {N/A, RTECSVS7700000, N/A} |
| DOT Hazard Class | 6.1 | 6.1 |
| DOT Numbers | 1558 | 2658 |
| EU Number | - | - |
| NFPA Fire Rating | 2 | 0 |
| NFPA Health Rating | 3 | 2 |
| NFPA Reactivity Rating | - | 0 |
| NFPA Hazards | - | - |
| AutoIgnition Point | - | - |
| Flashpoint | - | - |
Compare With Other Elements
Compare Arsenic and Selenium with other elements of the periodic table.