The alkali metals are so reactive that they are never found in nature in elemental form. Although some of their ores are abundant, isolating them from their ores is somewhat difficult. For these reasons, the group 1 elements were unknown until the early 19th century, when Sir Humphry Davy first prepared sodium (Na) and potassium (K) by passing an electric current through molten alkalis. (The ashes produced by the combustion of wood are largely composed of potassium and sodium carbonate.) Lithium (Li) was discovered 10 years later when the Swedish chemist Johan Arfwedson was studying the composition of a new Brazilian mineral. Cesium (Cs) and rubidium (Rb) were not discovered until the 1860s, when Robert Bunsen conducted a systematic search for new elements. Known to chemistry students as the inventor of the Bunsen burner, Bunsen’s spectroscopic studies of ores showed sky blue and deep red emission lines that he attributed to two new elements, Cs and Rb, respectively. Francium (Fr) is found in only trace amounts in nature, so our knowledge of its chemistry is limited. All the isotopes of Fr have very short half-lives, in contrast to the other elements in group 1.
Answer:
Molarity of a 5.0 L solution that contains 0.5 moles of KNO3 is 0.1 M
Explanation:
Molarity : It is used to express the concentration of the solution and defined as total moles of solute present in one liter of solution .
Moles of KNO3 = 0.5 (given)
Volume of solution = 5.0 L
Substitute the value in given formula ,
on calculation,
Molarity = 0.1 mol/L
Molarity = 0.1 M
(M = mol/L)
Answer:
1 the reproductive system. and the immune system is there to fight off any viruses or bacteria that had entered your body. If the bacteria is harmful it will be fought.
Answer:
2
b= they are grouped differently, but all the atoms are still there.
In order to balance this equation you need to count each element and how many of the individual elements are in the equation.
_H2+N2=2 NH3
You multiply the 2 (Which is the coefficient) by the 3 (which is the subscript) This would equal 6 which indicated there are 6 hydrogen atoms on the right side so the left side should also have 6 hydrogen atoms
The missing coefficient on the left side must multiple the 2 to become 6 hydrogen
Answer=3
