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A chemical element, often simply called an element, is a type of atom which has a specific number of protons in its atomic nucleus (i.e., a specific atomic number, or Z). [ 1 ] The definitive visualisation of all 118 elements is the periodic table of the elements , whose history along the principles of the periodic law was one of the founding ...
In 2013, compounds of sodium and chloride of different stoichiometries have been discovered; five new compounds were predicted (e.g., Na 3 Cl, Na 2 Cl, Na 3 Cl 2, NaCl 3, and NaCl 7). The existence of some of them has been experimentally confirmed at high pressures and other conditions: cubic and orthorhombic NaCl 3 , two-dimensional metallic ...
The collection includes videos, each just a few minutes long, for all 118 known elements with a video for each element, as well as many additional supplemental chemistry videos. The 118 element videos and introduction videos were all shot unscripted in June and July 2008. [5] Since the initial videos were completed in 2008 the team has been ...
Note: ρ is density, n is refractive index at 589 nm, [clarification needed] and η is viscosity, all at 20 °C; T eq is the equilibrium temperature between two phases: ice/liquid solution for T eq < 0–0.1 °C and NaCl/liquid solution for T eq above 0.1 °C.
A mnemonic is a memory aid used to improve long-term memory and make the process of consolidation easier. Many chemistry aspects, rules, names of compounds, sequences of elements, their reactivity, etc., can be easily and efficiently memorized with the help of mnemonics. This article contains the list of certain mnemonics in chemistry.
From cold solutions, salt crystallises as the dihydrate NaCl·2H 2 O. Solutions of sodium chloride have very different properties from those of pure water; the freezing point is −21.12 °C (−6.02 °F) for 23.31 wt% of salt, and the boiling point of saturated salt solution is around 108.7 °C (227.7 °F). [3]
The name of the cation (the unmodified element name for monatomic cations) comes first, followed by the name of the anion. [100] [101] For example, MgCl 2 is named magnesium chloride, and Na 2 SO 4 is named sodium sulfate (SO 2− 4, sulfate, is an example of a polyatomic ion).
Oxygen (1s 2 2s 2 2p 4), fluorine (1s 2 2s 2 2p 5), and neon (1s 2 2s 2 2p 6) then complete the already singly filled 2p orbitals; the last of these fills the second shell completely. [ 39 ] [ 58 ] Starting from element 11, sodium , the second shell is full, making the second shell a core shell for this and all heavier elements.