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The shortest-lived isotope of lithium is 4 Li, which decays through proton emission and has a half-life of 7.6 × 10 −23 s. [26] The 6 Li isotope is one of only five stable nuclides to have both an odd number of protons and an odd number of neutrons, the other four stable odd-odd nuclides being hydrogen-2, boron-10, nitrogen-14, and tantalum ...
Like the periodic table, the list below organizes the elements by the number of protons in their atoms; it can also be organized by other properties, such as atomic weight, density, and electronegativity. For more detailed information about the origins of element names, see List of chemical element name etymologies.
The periodic table, also known as the periodic table of the elements, is an ordered arrangement of the chemical elements into rows ("periods") and columns ("groups"). It is an icon of chemistry and is widely used in physics and other sciences.
Superactinides – Hypothetical series of elements 121 to 157, which includes a predicted "g-block" of the periodic table. Transactinide elements – Elements after the actinides (atomic number greater than 103). Transplutonium elements – Elements with atomic number greater than 94. Transuranium elements – Elements with atomic number ...
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 chemistry and atomic physics, the main group is the group of elements (sometimes called the representative elements) whose lightest members are represented by helium, lithium, beryllium, boron, carbon, nitrogen, oxygen, and fluorine as arranged in the periodic table of the elements.
Most Regents exams consist of a single three-hour testing period. The exception is the Earth Science exam, which consists of a 41-minute (approximate) laboratory component, known as the Earth Science lab practical, given around two weeks prior to the three-hour exam. The Regents exams are administered in January, June, and August.
Dilithium, Li 2, is a strongly electrophilic, diatomic molecule comprising two lithium atoms covalently bonded together. Li 2 has been observed in the gas phase. It has a bond order of 1, an internuclear separation of 267.3 pm and a bond energy of 102 kJ/mol or 1.06 eV in each bond. [1] The electron configuration of Li 2 may be written as σ 2 ...