Elements represent a whole, atoms represent an individual, and there must be oxygen atoms in the molecule. There is a general term because there are atoms with the same number of protons but different numbers of neutrons. They belong to the same element, but they are different atoms.
In chemistry, an element refers to a kind of atoms with the same nuclear charge number (or proton number). In mathematics, elements are the elements that make up a set and each object.
Chemical elements are a kind of atoms with the same nuclear charge number (the number of protons in the nucleus). From the philosophical point of view, elements are the result of qualitative change caused by quantitative change of proton number in atoms.
Common elements are hydrogen, nitrogen and carbon. Up to 20 19, * * 1 18 elements have been discovered, among which 94 elements exist on the earth. The nuclei of elements with atomic number ≥83 (bismuth and above) are unstable and will decay. Elements 43 and 6 1 (technetium and promethium) have no stable isotopes and will decay. The heaviest element in nature is 93 neptunium.
The origin of element thought is very early. Babylonians and ancient Egyptians once regarded water (and later air and soil) as the main element of the world, forming the theory of three elements. There were four theories in ancient India and five elements in ancient China.
The following are some application examples of elements:
1, carbon element: carbon is the foundation of life. Humans use carbon to make graphite, carbon black, carbon fiber and other materials, and it is also used in the manufacturing process of steel, alloy and polymer materials.
2. Hydrogen: Hydrogen is the most common element in the universe and is widely used in fuel cells, rocket fuels and other fields. Because it can produce clean water vapor when burning, it is also widely used in the field of environmental protection.
3. Metal elements: Metal elements have good electrical conductivity, thermal conductivity, hardness, toughness and other characteristics, so they are widely used in electronics, machinery, construction, aviation, aerospace and other fields, such as iron, copper, aluminum, magnesium, zinc, tungsten and so on.
4. Rare earth elements: Rare earth elements have the characteristics of magnetism, photoelectricity, superconductivity and fluorescence, and are widely used in nuclear fuel, medical care, electronics, new energy and other fields, such as cerium, neodymium, dysprosium, samarium, erbium, thulium and ytterbium.
5. Oxide elements: Oxide elements can produce distinctive colors and are used in glass, ceramics, glazes, dyes, electronic components and other fields, such as titanium dioxide, antimony oxide and copper oxide.