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In theoretical physics, negative mass is a hypothetical type of exotic matter whose mass is of opposite sign to the mass of normal matter, e.g. −1 kg. [1] [2] Such matter would violate one or more energy conditions and exhibit strange properties such as the oppositely oriented acceleration for an applied force orientation.
The alkaline earth metals (Be, Mg, Ca, Sr, Ba, and Ra) are the second most reactive metals in the periodic table, and, like the Group 1 metals, have increasing reactivity with increasing numbers of energy levels. Beryllium (Be) is the only alkaline earth metal that does not react with water or steam, even if the metal is heated red hot. [9]
According to a report published by the Water Footprint organization in 2010, a single kilogram of beef requires 15 thousand litres (3.3 × 10 ^ 3 imp gal; 4.0 × 10 ^ 3 US gal) of water; however, the authors also make clear that this is a global average and circumstantial factors determine the amount of water used in beef production.
Rubidium is a chemical element; it has symbol Rb and atomic number 37. It is a very soft, whitish-grey solid in the alkali metal group, similar to potassium and caesium. [9] Rubidium is the first alkali metal in the group to have a density higher than water.
For other isotopes, the isotopic mass is usually within 0.1 u of the mass number. For example, 35 Cl (17 protons and 18 neutrons) has a mass number of 35 and an isotopic mass of 34.96885. [7] The difference of the actual isotopic mass minus the mass number of an atom is known as the mass excess, [8] which for 35 Cl is –0.03115.
The alkali metals are among the most electropositive elements on the periodic table and thus tend to bond ionically to the most electronegative elements on the periodic table, the halogens (fluorine, chlorine, bromine, iodine, and astatine), forming salts known as the alkali metal halides. The reaction is very vigorous and can sometimes result ...
where mass number A equals to the sum of atomic number Z and number of neutrons N, and m p, m n, a V, a S, a C, a A are constants, one can see that the mass depends on Z and N non-linearly, even for a constant mass number. For odd A, it is admitted that δ = 0 and the mass dependence on Z is convex (or on N or N − Z, it does not matter for a ...
In the periodic table, potassium is one of the alkali metals, all of which have a single valence electron in the outer electron shell, which is easily removed to create an ion with a positive charge (which combines with anions to form salts). In nature, potassium occurs only in ionic salts.