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The chemical elements are what the periodic table classifies and organizes. Hydrogen is the element with atomic number 1; helium , atomic number 2; lithium , atomic number 3; and so on. Each of these names can be further abbreviated by a one- or two-letter chemical symbol ; those for hydrogen, helium, and lithium are respectively H, He, and Li ...
A quire of paper is a measure of paper quantity. The usual meaning is 25 sheets of the same size and quality: 1 ⁄ 20 of a ream of 500 sheets. Quires of 25 sheets are often used for machine-made paper, while quires of 24 sheets are often used for handmade or specialised paper of 480-sheet reams.
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 the United States, the weight is the weight of a ream (bundle of 500 sheets) of varying "basic sizes" before the paper is cut into the size it is sold to end customers. For example, a ream of 20 lb, 8.5 in × 11 in (216 mm × 279 mm) paper weighs 5 pounds because it has been cut from larger sheets into four pieces. [21]
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.
In the paper and fabric industries, it is called grammage and is expressed in grams per square meter (g/m 2); for paper in particular, it may be expressed as pounds per ream of standard sizes ("basis ream"). A related area number density can be defined by replacing mass by number of particles or other countable quantity, with resulting units of ...
Chemistry is a physical science concerned with the composition, structure, and properties of matter, as well as the changes it undergoes during chemical reactions; it features an extensive vocabulary and a significant amount of jargon. Note: All periodic table references refer to the IUPAC Style of the Periodic Table.
The basis weight of paper is the density of paper expressed in terms of the mass of a ream of given dimensions and a sheet count. In the US system, the weight is specified in avoirdupois pounds and the sheet count of a paper ream is usually 500 sheets. However, the mass specified is not the mass of the ream that is sold to the customer.