вторник, 30 ноября 2021 г.
Electron
Electron (noun, “Ee-LEK-trahn”)
This is one of the three types of particles that make up an atom. The other two are protons and neutrons. Protons and neutrons form the center, or nucleus, of an atom. Electrons exist in a surrounding cloud. They swarm around the center of the atom. That’s because electrons have negative electric charge. That makes them attracted to the positively charged protons in the nucleus. Normally, atoms have the same number of electrons as protons. So the atoms are electrically neutral.
Unlike protons and neutrons, electrons don’t contain smaller particles. That is, they are fundamental particles. Each electron is extremely small. Its mass is only about 1/1,800 the mass of a proton or neutron. Still, electrons play an important role in how atoms behave. Atoms of different elements hold their electrons in different arrangements around the nucleus. That arrangement gives each element its distinct properties. For instance, it determines how well an element conducts electricity. It also determines the temperature at which the element boils. And, that arrangement governs how likely atoms are to share electrons with each other. When atoms share electrons, they link together and form molecules.
Power words
atom: The basic unit of a chemical element. Atoms are made up of a dense nucleus that contains positively charged protons and uncharged neutrons. The nucleus is orbited by a cloud of negatively charged electrons.
cloud: A plume of molecules or particles, such as water droplets, that move under the action of an outside force, such as wind, radiation or water currents.
electric charge: The physical property responsible for electric force; it can be negative or positive.
electron: A negatively charged particle, usually found orbiting the outer regions of an atom; also, the carrier of electricity within solids.
fundamental: Something that is basic or serves as the foundation for another thing or idea.
ion: (adj. ionized) An atom or molecule with an electric charge due to the loss or gain of one or more electrons. An ionized gas, or plasma, is where all of the electrons have been separated from their parent atoms.
link: A connection between two people or things.
mass: A number that shows how much an object resists speeding up and slowing down — basically a measure of how much matter that object is made from.
matter: Something that occupies space and has mass. Anything on Earth with matter will have a property described as "weight."
molecule: An electrically neutral group of atoms that represents the smallest possible amount of a chemical compound. Molecules can be made of single types of atoms or of different types. For example, the oxygen in the air is made of two oxygen atoms (O2), but water is made of two hydrogen atoms and one oxygen atom (H2O).
neutron: A subatomic particle carrying no electric charge that is one of the basic pieces of matter. Neutrons belong to the family of particles known as hadrons.
nucleus: Plural is nuclei. (in physics) The central core of an atom, containing most of its mass.
particle: A minute amount of something.
plasma: (in chemistry and physics) A gaseous state of matter in which electrons separate from the atom. A plasma includes both positively and negatively charged particles.
proton: A subatomic particle that is one of the basic building blocks of the atoms that make up matter. Protons belong to the family of particles known as hadrons.
Chemists win Nobel Prize for faster, cleaner way of making molecules
Chemists win Nobel Prize for faster, cleaner way of making molecules
Making molecules is hard work. Atoms must be bonded together in specific arrangements through a series of chemical reactions. Those reactions often are slow and far from straightforward. They also can waste resources. The 2021 Nobel Prize in chemistry goes to two scientists who developed a tool some 20 years ago that revolutionized how chemists create new molecules. Their process is not only faster but also friendlier to the environment.
“This is a fitting recognition of very important work,” says H.N. Cheng. He’s president of the American Chemical Society, based in Washington, D.C. “We can think of chemists as magicians having magic wands in the lab,” Cheng says. “We wave the wand and a reaction goes on.” These Nobel laureates gave chemists “a new wand,” that’s drastically more efficient and less wasteful, he says.
That wand is a new way to speed the reactions that build specific molecules. It’s a process known as asymmetric organocatalysis (AY-sih-MEH-trik Or-gan-oh-kah-TAL-ih-sis). This year’s winners came up with the idea for it independently. One of the chemists, Benjamin List, works at the Max Planck Institute for Coal Research. It’s in Mülheim an der Ruhr, Germany. The other is David MacMillan. He works at Princeton University in New Jersey.
List’s and MacMillan’s work prompted others to seek out more organic catalysts and to study how they might be used. These catalysts tend to be small carbon-and-hydrogen molecules which might also include oxygen, nitrogen, sulfur and/or phosphorus.
Catalysis is a big deal. Roughly one-third of the world’s collective income depends on it, notes Peter Somfai. He’s a chemist at Lund University in Sweden and another member of the Nobel Committee for Chemistry. At an October 6 news conference announcing the new winners, he noted “We now have a new powerful tool available for making organic molecules.” He said it’s one that can be drastically more efficient and “greener” than previous methods.
And because this process eliminates use of toxic chemicals, it’s also a far more environmentally friendly process.
If building new molecules is like playing chess, asymmetric organocatalysis has “completely changed the game,” Somfai said. “It’s like adding a new chess piece that can move in different ways.”
For their achievements, List and MacMillan will each get a medal and share 10 million Swedish kroner (more than $1.1 million).