Search results
Results From The WOW.Com Content Network
List of chemical elements. 118 chemical elements have been identified and named officially by IUPAC. 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 periodic table is a tabular arrangement of the chemical elements, organized by their atomic number, electron configuration, and chemical properties. It is a useful tool for understanding the patterns and trends of the elements and their interactions. Learn more about the history, structure, and significance of the periodic table on Wikipedia.
For example, oxygen is necessary for fire. But one cannot assume that everywhere there is oxygen, there is fire. A condition X is sufficient for Y if X, by itself, is enough to bring about Y. For example, riding the bus is a sufficient mode of transportation to get to work.
Carbon. Carbon (from Latin carbo 'coal') is a chemical element; it has symbol C and atomic number 6. It is nonmetallic and tetravalent —meaning that its atoms are able to form up to four covalent bonds due to its valence shell exhibiting 4 electrons. It belongs to group 14 of the periodic table. [ 16]
Paradox. A paradox is a logically self-contradictory statement or a statement that runs contrary to one's expectation. [ 1][ 2] It is a statement that, despite apparently valid reasoning from true or apparently true premises, leads to a seemingly self-contradictory or a logically unacceptable conclusion. [ 3][ 4] A paradox usually involves ...
For example, some unicellular organisms have genomes much larger than that of humans. Cole's paradox: Even a tiny fecundity advantage of one additional offspring would favor the evolution of semelparity. Gray's paradox: Despite their relatively small muscle mass, dolphins can swim at high speeds and obtain large accelerations.
The classical elements were first proposed independently by several early Pre-Socratic philosophers. [6] Greek philosophers had debated which substance was the arche ("first principle"), or primordial element from which everything else was made. Thales (c. 626/623 – c. 548/545 BC) believed that water was this principle.
The history of the periodic table is also a history of the discovery of the chemical elements. The first person in recorded history to discover a new element was Hennig Brand, a bankrupt German merchant. Brand tried to discover the philosopher's stone —a mythical object that was supposed to turn inexpensive base metals into gold.