Answer:
Substances can change phase—often because of a temperature change. At low temperatures, most substances are solid; as the temperature increases, they become liquid; at higher temperatures still, they become gaseous.
The process of a solid becoming a liquid is called melting. (an older term that you may see sometimes is fusion). The opposite process, a liquid becoming a solid, is called solidification. For any pure substance, the temperature at which melting occurs—known as the melting point—is a characteristic of that substance. It requires energy for a solid to melt into a liquid. Every pure substance has a certain amount of energy it needs to change from a solid to a liquid. This amount is called the enthalpy of fusion (or heat of fusion) of the substance, represented as ΔHfus. Some ΔHfus values are listed in Table 10.2 “Enthalpies of Fusion for Various Substances”; it is assumed that these values are for the melting point of the substance. Note that the unit of ΔHfus is kilojoules per mole, so we need to know the quantity of material to know how much energy is involved. The ΔHfus is always tabulated as a positive number. However, it can be used for both the melting and the solidification processes as long as you keep in mind that melting is always endothermic (so ΔH will be positive), while solidification is always exothermic (so ΔH will be negative).
Table 10.2 Enthalpies of Fusion for Various Substances
Explanation:
I think 310.2 g/mol
hope this helps
They can probably form 3 of them
Answer:
Group VII
Explanation:
The electronegativity of an element is the tendency of the atoms of that element to attract electrons that are shared with other atoms.
Each element has a different electronegativity from other elements. In particular:
- Electronegativity increases as we move towards the right along the periodic table - this is due to the fact that as we move to the right, the number of valence electrons in the atom increases, and therefore the tendency of the atom to attract more electrons increases more, in order to fill the valence shell. In fact, the most electronegative group is group VII, which is the last but on one on the right (the last group on the right, VIII, is the group containing the noble gases, which do not react at all, so they do not attract electrons)
- Electronegavity also decreases as we move downward along the periodic table - this is because as we move downward, the number of shells and electrons around the atom increase, so all these electrons "shield" the nucleus (which is positively charged, so it is the one attracting the electrons from other atoms), and so the tendency to attract more electrons decreases.
So, the group of element most electronegative is
VII