lewis
lewis — noun
1. a chemical substance that can take a lone electron pair offered by another subst
a chemical substance that can take a lone electron pair offered by another substance (a Lewis base) and use that pair to create a new covalent bond. Unlike traditional acids, a Lewis acid does not need to release hydrogen ions.
Boron trifluoride acts as a Lewis acid when it accepts electrons from ammonia.
collocation: act as a Lewis acid
The chemistry teacher explained that a Lewis acid must have an empty orbital to receive electrons.
grammar pattern: Lewis acid + must + infinitive
Aluminium chloride is a common Lewis acid used in organic synthesis to speed up reactions.
Unlike a Brønsted acid, a Lewis acid does not need to donate a hydrogen ion.
Students in the lab tested whether copper ions could behave as a Lewis acid in solution.
- electron-pair acceptor
full descriptive name, clarifies the mechanism
- Lewis acceptor
shorter term used in advanced chemistry contexts
- Lewis base
the substance that donates the electron pair in the reaction
用法筆記
Almost always capitalised because it is named after the chemist Gilbert N. Lewis. Frequently appears in the paired phrase 'Lewis acid and Lewis base'. The key structural feature is an empty orbital that can accept an electron pair.
常見錯誤
2. a set of three iron wedges that fit together inside a specially cut dovetail-sha
a set of three iron wedges that fit together inside a specially cut dovetail-shaped hole in a large block of stone. When a crane chain is attached to the top ring of the device, the wedges grip the stone tightly so it can be lifted safely.
The stonemason cut a dovetail hole in the granite block to receive the lewis.
collocation: cut/receive a lewis
Workers inserted the three iron wedges of the lewis into the stone before hooking up the crane.
collocation: insert the wedges of the lewis
Without a lewis, lifting a five-ton marble slab would be nearly impossible on a medieval building site.
The Cathedral restoration team used a modern steel lewis to raise each damaged stone block.
When the lewis is in place, its wedges spread outward inside the hole and lock against the stone.
- lewis bolt
alternative name emphasising the bolt-like shape
- lewis pin
regional variant, especially in British quarrying
- dovetail lifting wedge
fully descriptive term explaining the mechanism
用法筆記
A highly specialised term found almost exclusively in stonemasonry, heritage building restoration, and quarrying contexts. Also called a 'lewis bolt' or 'lewis pin' in some regional dialects. The device is named after the person who popularised its design, though the exact origin is debated.
常見錯誤
lewis — noun
1. the surname of several notable people in literature, science, exploration, and p
the surname of several notable people in literature, science, exploration, and public life. Listed below are seven prominent figures who share this name.
C.S. Lewis wrote The Chronicles of Narnia, a series beloved by children around the world.
C.S. Lewis — British author
Meriwether Lewis led the famous Lewis and Clark Expedition across the American West in 1804.
Meriwether Lewis — American explorer
Sinclair Lewis was the first American writer to win the Nobel Prize in Literature, in 1930.
Edward B. Lewis won the Nobel Prize for his research on how genes control the development of embryos.
John L. Lewis organised coal miners into one of the most powerful labour unions in American history.
Matthew Gregory Lewis, known as Monk Lewis, wrote the famous Gothic novel The Monk in 1796.
Wyndham Lewis founded the Vorticist art movement in London and wrote several novels and essays.