b2o3 molecular or ionic compound b2o3 molecular or ionic compound

B. P waves cause damage, and S waves do not cause damage. which elements have higher electronegatives and why? Explain why this property is expected on the basis of the structure of diamond. Several examples are found in Table 3.3.1. f. non polar covalent, 6.67 For each of the following bonds, indicate the positive end and the negative end with. Write the symbol and name for the ion that has 7 protons and 10 electrons. a. BrF b. KCl d. Cl2, a. polar dipole dipole attraction For example, the average oxygen coordination number in v-B2O3 at 1 atm is 2 [the average cation coordination number (3) 2/3]. National Library of Medicine. Binary Molecular and Ionic compound names: Formula Ionic or molecular compound Compound Name B2O3 Partially Molecular and partially ionic Boron trioxide N2O Molecular compound Nitrous oxide LiCl Ionic View the full answer Transcribed image text: Page Exercise 2: Naming Chemical Compounds Data Table 2. shapes molecules can take up are trigonal planar or bent. (NH4)2S Boron trioxide L. McCulloch (1937): "A Crystalline Boric Oxide". H2 has a nonpolar covalent bond, but HCl has a polar covalent bond. BaBr 2 is barium bromide. rank the different types of attractive forces of from least to greatest. f. SrBr2, a. magnesium chloride Thus, the electronic structure of boron nitride is similar to graphite. For example, graphite, the other common allotrope of carbon, has the structure shown in part (b) in Figure \(\PageIndex{1}\). In fact, diamond (melting point = 3500C at 63.5 atm) is one of the hardest substances known, and silicon carbide (melting point = 2986C) is used commercially as an abrasive in sandpaper and grinding wheels. A. ionic. ex. a. Si-Br a. potassium and sulfur d. MgF2 The reactions are: Boric acid goes to anhydrous microcrystalline B2O3 in a heated fluidized bed. NaCl. The bonding between chemical subunits, however, is identical to that within the subunits, resulting in a continuous network of chemical bonds. Rules for naming binary ionic compound were discussed in Section 5.5. a. lithium and chlorine forms bonds by sharing electrons. On this Wikipedia the language links are at the top of the page across from the article title. Forms sulfur dioxide and phosphorus pentaoxide during combustion. e. magnesium oxide d. Mg2+, O2+, MgO. All exhibit high thermal and electrical conductivity, metallic luster, and malleability. The a layer of the graphite structure consists of a repeating series of rings. a. Al3+ and Cl- 6.11 Which of the following pairs of elements are likely to form an ionic compound? 109 degrees angles always exist. Which atoms are most likely to form double and triple bonds? It is inexpensive and available over the counter in small, clear gelatin capsules (called boric acid vaginal suppositories) that are inserted intravaginally, often with the help of an applicator. Are the properties of ionic compounds the same as their original elements alone? Covalent solids consist of two- or three-dimensional networks of atoms held together by covalent bonds; they tend to be very hard and have high melting points. What determines the attrac- tion between two H atoms? Crystalline solids fall into one of four categories. Compound Name 1 B2O3 2 N2O 3 LiCl 4 N2O4 This problem has been solved! How can you tell if a molecule would be a polar molecule? Is this conduction or sensorineural deafness? Li+, N3-. e. S, 6.3 State the number of electrons lost or gained when the following elements form ions: Ionic compounds have higher melting points. Boron Oxide may damage the liver and kidneys. D. P waves push and pull in the same direction as the wave, and S waves move up and down. Polyatomic ions. c. P4S3 Greek prefixes are not used for binary ionic compounds. # Formula Molecular or Ionic Compound? d. Zn3(PO4)2 Group 2A b. CaCl2 dipole-dipole, hydrogen bonds, and dispersion forces are intermolecular attractions. b. magnesium phosphate Discharge from yeast infections doesnt usually have a strong smell but may look like cottage cheese. Page Exercise 2: Naming Chemical Compounds Data Table 2. f. barium fluoride, 6.18 Write the name for each of the following ionic compounds: What is the hybridization of carbon in diamond? what is the significance of hydrogen bonds in intermolecular attractions? To classify solids as ionic, molecular, covalent (network), or metallic, where the general order of increasing strength of interactions. 3 protons, 2 electrons Worked example: Finding the formula of an ionic compound. This model does not, however, explain many of the other properties of metals, such as their metallic luster and the observed trends in bond strength as reflected in melting points or enthalpies of fusion. The structure of crystalline quartz (SiO2), shown in Section 12.1, can be viewed as being derived from the structure of silicon by inserting an oxygen atom between each pair of silicon atoms. The general order of increasing strength of interactions in a solid is: molecular solids < ionic solids metallic solids < covalent solids. b. c. AgI Molecular solids are held together by relatively weak forces, such as dipoledipole interactions, hydrogen bonds, and London dispersion forces. [19][1], The trigonal network undergoes a coesite-like transformation to monoclinic -B2O3 at several gigapascals (9.5 GPa). HCl is a polar covalent due to the greater electronegativity difference between the charges, Using electronegativity values, classify each of the following bonds as nonpolar covalent, polar covalent, or ionic: by using the root of the atom name followed by the suffix -ide. 2: Writing Chemical Formulas It has been hypothesized that C60 would make a good lubricant. For a polar molecule with a dipole such as HCl, the partially positive H atom of one HCl molecule attracts the partially negative Cl atom in another HCl molecule. An earthquake has a high magnitude but a low intensity. C. the amount of damage that results from an earthquake 6.31 Write the formula including the charge for each of the following polyatomic ions: b. ionic Cu is a transitional variable charge element and so roman numeral indicating the charge of specific ion is included in the naming. ], Skin: Prevent skin contact Eyes: Prevent eye contact Wash skin: When contaminated Remove: When wet or contaminated Change: No recommendation, NIOSH REL : TWA 10 mg/m 3 OSHA PEL ? Formula Write the symbol and name for the ion that has 20 protons and 18 electrons. Exposure to Boron Oxide can cause headache, dizziness, nausea and vomiting. d. copper(II) sulfide how many electrons must an atom have on its outer shell to remain stable? Download for free at http://cnx.org/contents/85abf193-2bda7ac8df6@9.110). It tells about the shape and characteristics of a signal in the form of a wave. c. Li+ and S2- c. sodium and phosphorus Metals are characterized by their ability to reflect light, called luster, their high electrical and thermal conductivity, their high heat capacity, and their malleability and ductility. made up of metal + nonmetal. (As a comparison, the molecular compound water melts at 0 C and boils at 100 C.) This agrees with our prediction. Boron trioxide Molecular Formula B O Average mass 69.620 Da Monoisotopic mass 70.003357 Da ChemSpider ID 452485 More details: Names Properties Searches Spectra Vendors Articles More Names and Synonyms Database ID (s) Validated by Experts, Validated by Users, Non-Validated, Removed by Users Boron trioxide [Wiki] 1303-86-2 [RN] 215-125-8 [EINECS] +2 charge, loses 2 electrons Unit 1: Lesson 3. Compounds that are composed of only non-metals or semi-metals with non-metals will display covalent bonding and will be classified as molecular compounds. e. Mn2+, a. b. b. Br-Br The entire solid is an "endless" repetition of carbon atoms bonded to each other by covalent bonds. what is the electron group geometry of a central atom with 3 electron groups and what variations of shapes do molecules form? Be aware that in the "ball-and-stick" representation the size of the balls do not accurately represent the size of carbon atoms. Lithium Selenide Potassium Oxide K2O HBr Hydrogen Bromide Diboron Trioxide B2O3 Ionic or Covalent: K2O Ionic Ionic or Covalent: B2S3 Covalent What is the name of B2S3? Dipole-dipole forces are attractions between oppositely charged regions of polar molecules. But the chances of getting it seem to go up with the number of sexual partners a woman has. new sex partners or many different sex partners (male or female). First element written in its entirety, second element only first syllable used followed by suffix -ide. a. H2S As a result, graphite exhibits properties typical of both covalent and molecular solids. How can you tell if a molecule would be a non polar molecule? Ionic solids tend to have high melting points and are rather hard. We also acknowledge previous National Science Foundation support under grant numbers 1246120, 1525057, and 1413739. Metallic solids have unusual properties: in addition to having high thermal and electrical conductivity and being malleable and ductile, they exhibit luster, a shiny surface that reflects light. Molecular compounds are the most common amongst the two. Laboratory Chemical Safety Summary (LCSS) Datasheet, SELENIUM HEXAFLUORIDE 7783-79-1 selenium(VI) fluoride UNII-H91D37I668 Selenium fluoride (SeF6), (OC-6-11)- More, Pay attention to vaginal hygiene. National Institute for Occupational Safety and Health, "Boroxol rings from diffraction data on vitreous boron trioxide", "Liquid B2O3 up to 1700K: X-ray diffraction and boroxol ring dissolution", "Crystal Growth Kinetics of Boron Oxide Under Pressure", "Structural transformations in liquid, crystalline and glassy B, National Pollutant Inventory: Boron and compounds, CDC - NIOSH Pocket Guide to Chemical Hazards - Boron oxide, https://en.wikipedia.org/w/index.php?title=Boron_trioxide&oldid=1129478170, Pages using collapsible list with both background and text-align in titlestyle, Articles containing unverified chemical infoboxes, Articles with unsourced statements from December 2022, Creative Commons Attribution-ShareAlike License 3.0, The inert capping layer in the Liquid Encapsulation Czochralski process for the production of, This page was last edited on 25 December 2022, at 16:03. How do they differ? (See the IUPAC Provisional Recommendation on the definition of a hydrogen bond.) One common examples of network solids are diamond (a form of pure carbon) Carbon exists as a pure element at room temperature in three different forms: graphite (the most stable form), diamond, and fullerene. c. State the number of electrons that must be lost or gained for each to achieve an octet. A molecular compound consists of molecules whose formula represents the actual number of atoms bonded together in the molecule. d. Na The root name of bromine is brom-. The arrangement of the molecules in solid benzene is as follows: Because the intermolecular interactions in a molecular solid are relatively weak compared with ionic and covalent bonds, molecular solids tend to be soft, low melting, and easily vaporized (\(H_{fus}\) and \(H_{vap}\) are low). What types of bonds make up compounds and which is the most prevalent? Ionic compounds have different properties than that of the elements it is composed of would have when alone. Much of the study of chemistry, however, involves looking at what happens . Compounds that are composed of only non-metals or semi-metals with non-metals will display covalent bonding and will be classified as molecular compounds. Notes-B 2 O 3 is a low melting glass of low thermal expansion and surface tension.It is an extremely useful oxide, indispensable in many industries and applications. f. cobalt(III) fluoride, a. MgCl2 Later in this chapter we will see that many covalent compounds have bonds that are highly polarized with greater electron density around one atom than the other. noble gases in group 8a, these are already stable with 8 valence electrons on outermost shell. A. the distance from the epicenter of an earthquake b. impossible, both anions thus it will not be balanced the eletronegativity difference between two atoms. Anions tend to be larger due to gaining an electron which causes a slight negative charge. Most are anions with -1,-2,3 charge. The melting points of metals, however, are difficult to predict based on the models presented thus far. intermolecular attractions occur between two molecules whereas intramolecular forces involve the direct bonding of atoms for form molecules such as in covalent or ionic bonds. For example, the average oxygen coordination number in v-B2O3 at 1 atm is 2 [the average cation coordination number (3) 2/3]. e. N-P It is then decanted, cooled and obtained in 9697% purity.[3]. Metallic solids such as crystals of copper, aluminum, and iron are formed by metal atoms Figure \(\PageIndex{5}\). Binary Molecuar and lonic Compound Names Formula B20 N20 Molecular or lonic Compound? With B 2 O 3 in a glaze you can make it melt at almost any common kiln temperature you want, and get a brilliant finish that will not craze. The ionic compound breaks down into ions when dissolved in water. The compound tetraphosphorus pentasulfide is a covalent compound as the molecule is formed by covalent bonds, in which the atoms share one pair or more than one pair of valence electrons. b. a molecule with a central atom that has four electron groups a. oxygen difluoride The atoms are joined to give a definite shape which is defined by the angles between the bonds and by the bond lengths. Compound Name 2.) How many protons and electrons are in each of the following ions? The sum of the charges are always 0, thus ions must balance each other out in an ionic compound. Table \(\PageIndex{2}\) compares the strengths of the intermolecular and intramolecular interactions for three covalent solids, showing the comparative weakness of the interlayer interactions. d. Ga3+, O2-; Ga2O3, 6.16 Write the symbols for the ions, and the correct formula for the d. PCl5 For example, the melting points of benzene (C6H6), naphthalene (C10H8), and anthracene (C14H10), with one, two, and three fused aromatic rings, are 5.5C, 80.2C, and 215C, respectively. Which statement best explains this? and four bonded atoms. Consist of two or more nonmetals that share one or more valence electrons, resulting in a covalent bond. In other words, total amount of positive charge is equal to total amount of negative charge. Data Table 1: Binary Molecular and Ionic Compound Names What is the electron group geometry of a central atom with two electron groups and what shape do molecules take? Self-healing rubber is an example of a molecular solid with the potential for significant commercial applications. Consider the elements aluminum and oxygen. This behavior is most obvious for an ionic solid such as \(NaCl\), where the positively charged Na+ ions are attracted to the negatively charged \(Cl^-\) ions. Atoms are the smallest units of matter that still retain the fundamental chemical properties of an element. b. K+, most prevalent positive ion in cells, needed for muscle a. O2-, used to build biomolecules and water Some compounds can form more than 8 valence electrons. f. Impossible, two anions cannot balance, 6.13 Write the correct ionic formula for the compound formed between each of the following pairs of ions: b. PbO2 They are soluble in nature. c. Group 7a Instead these electrons exist in molecular orbitals that are delocalized over many atoms, producing an electronic band structure. a. MgCl Compounds can be classified as ionic or covalent. How do you determine shape of a molecule? d. NO3-, a. sulfate Boric acid will initially decompose into steam, (H2O(g)) and metaboric acid (HBO2) at around 170C, and further heating above 300C will produce more steam and diboron trioxide. 2. b In which cases the attractive forces of a solid are broken causing it to change into liquid. Because of its resonance structures, the bonding in graphite is best viewed as consisting of a network of CC single bonds with one-third of a bond holding the carbons together, similar to the bonding in benzene. 1.) Formula Tribromine octoxide Lithium selenide lodine monochloride Nitrogen. A molecular compound consists of molecules whose formula represents the actual number of atoms bonded together in the molecule. b. dichlorine oxide d. magnesium oxide b. polar covalent In metallic solids, the valence electrons are no longer exclusively associated with a single atom. National Center for Biotechnology Information . Draw an arrow to show the dipole for each. O ion is 2-. we know that there are 2 atoms of Cu,there fore to balance the equation, we know it will be Cu+ ions used instead of Cu2+. When an electrical potential is applied, the electrons can migrate through the solid toward the positive electrode, thus producing high electrical conductivity. F-, flouride Nonmetal atoms in polyatomic ions are joined by covalent bonds, but the ion as a whole participates in ionic bonding. b. P2O5 The laundry aisle at grocery stores and big-box stores, such as Wal-Mart. What are dispersion forces and how do they occur? b. Fe2O3 Valence electrons in a metallic solid are delocalized, providing a strong cohesive force that holds the atoms together. Na 2 O melts as well or better than B 2 O 3, but unlike B 2 O 3, its high thermal . For example, the structure of diamond, shown in part (a) in Figure \(\PageIndex{1}\), consists of sp3 hybridized carbon atoms, each bonded to four other carbon atoms in a tetrahedral array to create a giant network. What are the two exceptions of polyatomic ions ending in -ate or -ite? Therefore for its definite shape and definite bond length, angle it is considered as molecular. b. Si2Br6 , leased by the earthquake, while intensity measures the amount of damage. +2 charge, loses two electrons Ionic . Molecular compound The study of coordinate. and three bonded atoms. e. Selenium hexaflouride, 6.47 Write the formula for each of the following molecular compounds: A 50.0-g silver object and a 50.0-g gold object are both added to 75.5mL75.5 \mathrm{~mL}75.5mL of water contained in a graduated cylinder. 1. none match, linear applies to two electron groups attached and no lone pair electrons. The actual melting points are C60, about 300C; AgZn, about 700C; BaBr2, 856C; and GaAs, 1238C. Boron oxide will also form when diborane (B2H6) reacts with oxygen in the air or trace amounts of moisture: Molten boron oxide attacks silicates. Another method is heating boric acid above ~300C. a group of covalently bonded atoms with an overall charge. c. N3- Nitride Due to strong covalent bonding within the layers, graphite has a very high melting point, as expected for a covalent solid (it actually sublimes at about 3915C). d. radium, a. Cl- Chloride It can be obtained with prologed annealing of the amorphous solid ~200C under at least 10 kbar of pressure. a. RbI contains a metal from group 1 and a nonmetal from group 17, so it is an ionic solid containing Rb+ and I ions. a. cobalt(III) chloride Metallic bonds tend to be weakest for elements that have nearly empty (as in Cs) or nearly full (Hg) valence subshells, and strongest for elements with approximately half-filled valence shells (as in W). c. copper(I) oxide What is the new water level in the cylinder (see Table 2.9)? 12.5: Network Covalent Solids and Ionic Solids is shared under a CC BY-NC-SA 4.0 license and was authored, remixed, and/or curated by LibreTexts. b. diphosphorous pentoxide CaO forms to give an overall balanced charge of 0. To understand the correlation between bonding and the properties of solids. a. hydrogen carbonate (bicarbonate) . Names and formulas of ionic compounds. Which group of elements do not combine with elements to form compounds? What is a molecular and ionic compound ? 1.) a. Fe2+ d. zinc phosphate CSID:452485, http://www.chemspider.com/Chemical-Structure.452485.html (accessed 07:21, Mar 4, 2023), Validated by Experts, Validated by Users, Non-Validated, Removed by Users, Predicted data is generated using the ACD/Labs Percepta Platform - PhysChem Module, Predicted data is generated using the US Environmental Protection Agencys EPISuite, Click to predict properties on the Chemicalize site, For medical information relating to Covid-19, please consult the. As a result, the melting points of the metals increase to a maximum around group 6 and then decrease again from left to right across the d block. e. Cu3P Even in the absence of ions, however, electrostatic forces are operational. )%2F12%253A_Intermolecular_Forces%253A_Liquids_And_Solids%2F12.5%253A_Network_Covalent_Solids_and_Ionic_Solids, \( \newcommand{\vecs}[1]{\overset { \scriptstyle \rightharpoonup} {\mathbf{#1}}}\) \( \newcommand{\vecd}[1]{\overset{-\!-\!\rightharpoonup}{\vphantom{a}\smash{#1}}} \)\(\newcommand{\id}{\mathrm{id}}\) \( \newcommand{\Span}{\mathrm{span}}\) \( \newcommand{\kernel}{\mathrm{null}\,}\) \( \newcommand{\range}{\mathrm{range}\,}\) \( \newcommand{\RealPart}{\mathrm{Re}}\) \( \newcommand{\ImaginaryPart}{\mathrm{Im}}\) \( \newcommand{\Argument}{\mathrm{Arg}}\) \( \newcommand{\norm}[1]{\| #1 \|}\) \( \newcommand{\inner}[2]{\langle #1, #2 \rangle}\) \( \newcommand{\Span}{\mathrm{span}}\) \(\newcommand{\id}{\mathrm{id}}\) \( \newcommand{\Span}{\mathrm{span}}\) \( \newcommand{\kernel}{\mathrm{null}\,}\) \( \newcommand{\range}{\mathrm{range}\,}\) \( \newcommand{\RealPart}{\mathrm{Re}}\) \( \newcommand{\ImaginaryPart}{\mathrm{Im}}\) \( \newcommand{\Argument}{\mathrm{Arg}}\) \( \newcommand{\norm}[1]{\| #1 \|}\) \( \newcommand{\inner}[2]{\langle #1, #2 \rangle}\) \( \newcommand{\Span}{\mathrm{span}}\)\(\newcommand{\AA}{\unicode[.8,0]{x212B}}\), Carbon: An example of an Covalent Network Solid, http://cnx.org/contents/85abf193-2bda7ac8df6@9.110, status page at https://status.libretexts.org, Variable Hardness and Melting Point (depending upon strength of metallic bonding), Conducting, melting points depend strongly on electron configuration, easily deformed under stress; ductile and malleable. The number of boroxol rings decays in the liquid state with increasing temperature. The atoms within such a metallic solid are held together by a unique force known as metallic bonding that gives rise to many useful and varied bulk properties. Naming monatomic ions and ionic compounds. Compounds that do not contain ions, but instead consist of atoms bonded tightly together in molecules (uncharged groups of atoms that behave as a single unit), are called covalent compounds. d. I A coordinate covalent bond is also known as a dative bond, which is a type of covalent bond. This page titled 3.4: Identifying Molecular and Ionic Compounds is shared under a CC BY-SA 4.0 license and was authored, remixed, and/or curated by Paul R. Young (ChemistryOnline.com) via source content that was edited to the style and standards of the LibreTexts platform; a detailed edit history is available upon request. In the compound B2O3, the two boron atoms are bonded together and held by the three oxygen atoms at its sides. At temperatures above 750C, the molten boron oxide layer separates out from sodium sulfate. Convert grams B2O3 to moles or moles B2O3 to grams Molecular weight calculation: 10.811*2 + 15.9994*3 Percent composition by element Calculate the molecular weight of a chemical compound Enter a chemical formula: A child is brought to the speech therapist because she does not pronounce high-pitched sounds (like "s"). 9 protons, 10 electrons Name is Copper(I) oxide. d. Mg3P2 b. Na+, N3-; Na3N Is P4S5 a ionic compound? How can you determine which charge is the correct charge for the transition element in an ionic compound? a. In the late 1980's synthetic methods were developed for the synthesis of C60, and the ready availability of this form of carbon led to extensive research into its properties. Instead, the valence electrons are delocalized throughout the crystal, providing a strong cohesive force that holds the metal atoms together. # Example 5.8. Its acidity slightly decreases as you get older, with its pH level rising closer to 5. c. CCl4 Boric anhydride | B2O3 | CID 518682 - structure, chemical names, physical and chemical properties, classification, patents, literature, biological activities, safety/hazards/toxicity information, supplier lists, and more. The melting and boiling point of molecular . Example, Cl is chlorine, Cl- is chloride. Differences between Ionic and Molecular Compounds In this model, the valence electrons are not tightly bound to any one atom but are distributed uniformly throughout the structure. If wetted, the project reacts exothermically, forming boric acid, so maintaining the integrity of the packaging is also essential. b. Al3+ and Br- Variable charge is when a metal has two or more ion types. d. 11 protons, 10 electrons. The formula of the carbonate ion is CO 32. a. CS2 Thus light of virtually all wavelengths is absorbed. The variation in the relative strengths of these four types of interactions correlates nicely with their wide variation in properties. Here Are Some Places You Can Usually Find Borax. If only non polar covalent bonds exist. c. N-N B. they are significant in formation and structure of DNA and proteins. Ionic compounds and molecular compounds are the two bonds that make up compounds. I love to write and share science related Stuff Here on my Website. Roman numerals follow the cation in the naming. Borax is a mineral that is taken straight from the ground (a form of the element Boron) and used in cleaning products. Although the elemental composition of most alloys can vary over wide ranges, certain metals combine in only fixed proportions to form intermetallic compounds with unique properties. It is difficult to deform or melt these and related compounds because strong covalent (CC or SiSi) or polar covalent (SiC or SiO) bonds must be broken, which requires a large input of energy. The reactions are: H3BO3 HBO2 + H2O. Classify C60, BaBr2, GaAs, and AgZn as ionic, covalent, molecular, or metallic solids and then arrange them in order of increasing melting points. D. the total amount of energy released by an earthquake. if molecule is not symmetrical. c. Na-O, a. polar covalent d. Cesium fluoride The compound B2O3 is molecular. When all 4 electron groups are bonded to central atom, a tetrahedral shape with 109 degrees angles form. BV isnt considered a sexually transmitted disease (STD). e. potassium iodide Molecular compounds are the most common amongst the two What are molecular compounds and what is the resulting bond called? b. carbonate c. phosphorus trichloride Experts are tested by Chegg as specialists in their subject area. 6.1 State the number of electrons that must be lost by atoms of each of the following to achieve a stable electron configuration: 4. c e. N-P, a. N-F what factor is dependent on polarity of bonds? d. zinc phosphide It is one of the most difficult compounds known to crystallize. D. Magnitude measures the energy released by the earthquake, while intensity measures its duration. b. Ca2+ and S2- Arrange the solids in order of increasing melting points based on your classification, beginning with molecular solids. Tetraphosphorus pentasulfide Tetraphosphorus pentasulfide is the name of the compound of the given formula P4S5 . b. Cl-As Ca2+, O2-. As is evident from the display, C60 is a sphere composed of six-member and five-member carbon rings. a. Li, Na, K Textbook content produced by OpenStax College is licensed under a Creative Commons Attribution License 4.0 license.