This assumption is not valid because, there are some elements which exist in two or more forms; they have the same atomic number but differ in their mass number, which meas that they possess different number of neutrons. These type of element are called isotopes. Isotope have the same atomic number and similar physical and chemical properties but they have different number of neutrons and therefore possess different masses.
Explanation:
Air has a heat capacity of about 700 Joules per kg per °K and a density of just 1.2 kg/m3, so its initial energy would be 700 x 1 x 1.2 x 293 = 246,120 Joules
Iron Fluoride
A chemical compound is a substance composed of atoms from two or more (different) elements. These compounds are formed by the creation of chemical bonds between the atoms of the different elements.
Helium and Neon are both elements, and in particular, they belong to a group of chemical elements called noble gases. Being noble gases, they are very stable and do not react easily.
Iron fluoride is a chemical compound consisting of the metal, iron, and the nonmetal, fluorine. When a metal and a nonmetal react to form a compound, they form ionic bonds to hold together the atoms of the different elements comprising the compound.
Answer:
Roxanne said it was because chlorine is highly electronegative and sodium has a low ionization energy and that the ions Na and cr both have full electron shells.