An "on-off-on" fluorescent nanoprobe for recognition of chromium(VI) and ascorbic acid based on phosphorus/nitrogen dual-doped carbon quantum dot.

See more Carbon products. Carbon (atomic symbol: C, atomic number: 6) is a Block P, Group 14, Period 2 element. The number of electrons in each of Carbon's shells is 2, 4 and its electron configuration is [He]2s² 2p². In its elemental form, carbon can take various physical forms (known as allotropes) based on the type of bonds between carbon atoms; the most well known allotropes are diamond, graphite, amorphous carbon, glassy carbon, and nanostructured forms such as carbon nanotubes, fullerenes, and nanofibers . Carbon is at the same time one of the softest (as graphite) and hardest (as diamond) materials found in nature. It is the 15th most abundant element in the Earth's crust, and the fourth most abundant element (by mass) in the universe after hydrogen, helium, and oxygen. Carbon was discovered by the Egyptians and Sumerians circa 3750 BC. It was first recognized as an element by Antoine Lavoisier in 1789.

See more Nitrogen products. Nitrogen is a Block P, Group 15, Period 2 element. Its electron configuration is [He]2s²2p³. Nitrogen is an odorless, tasteless, colorless and mostly inert gas. It is the seventh most abundant element in the universe and it constitutes 78.09% (by volume) of Earth's atmosphere. Nitrogen was discovered by Daniel Rutherford in 1772.

See more Phosphorus products. Phosphorus (atomic symbol: P, atomic number: 15) is a Block P, Group 15, Period 3 element. The number of electrons in each of Phosphorus's shells is 2, 8, 5 and its electronic configuration is [Ne] 3s² 3p³. The phosphorus atom has a radius of 110.5.pm and its Van der Waals radius is 180.pm. Phosphorus is a highly-reactive non-metallic element (sometimes considered a metalloid) with two primary allotropes, white phosphorus and red phosphorus its black flaky appearance is similar to graphitic carbon. Compound forms of phosphorus include phosphates and phosphides. Phosphorous was first recognized as an element by Hennig Brand in 1669 its name (phosphorus mirabilis, or "bearer of light") was inspired from the brilliant glow emitted by its distillation.

See more Chromium products. Chromium (atomic symbol: Cr, atomic number: 24) is a Block D, Group 6, Period 4 element with an atomic weight of 51.9961. The number of electrons in each of Chromium's shells is 2, 8, 13, 1 and its electron configuration is [Ar] 3d⁵ 4s¹. Louis Nicolas Vauquelin first discovered chromium in 1797 and first isolated it the following year. The chromium atom has a radius of 128 pm and a Van der Waals radius of 189 pm. In its elemental form, chromium has a lustrous steel-gray appearance. Chromium is the hardest metallic element in the periodic table and the only element that exhibits antiferromagnetic ordering at room temperature, above which it transforms into a paramagnetic solid. The most common source of chromium is chromite ore (FeCr₂O₄). Due to its various colorful compounds, Chromium was named after the Greek word 'chroma.' meaning color.