The atomic number represents the number of protons in an atom's nucleus. In an uncharged atom, the number of protons is always equal to the number of electrons. For example, carbon atoms include six protons and six electrons, so carbon's atomic number is 6.
Answer:
44 grams/mole
Explanation:
<u>If 1 mol of XO₂ contains the same number of atoms as 60 g of XO3, what is the molar mass of XO₂?</u>
<u></u>
60 grams of XO3 is one mole XO3, since it has the same number of atoms as 1 mole of XO2.
Let c be the molar mass of X. The molar mass of XO3 is comprised of:
X: c
3O: 3 x 16 = 48
Total molar mass of XO3 is = <u>48 + c</u>
We know that the molar mass of XO3 = 60 g/mole, so:
48 + c = 60 g/mole
c = 12 g/mole
The molar mass of XO2 would be:
1 X = 12
2 O = 32
Molar mass = 44 grams/mole, same as carbon dioxide. Carbon's molar mass is 12 grams.
<u></u>
<u></u>
Answer:
a. A reaction in which the entropy of the system increases can be spontaneous only if it is endothermic.
Explanation:
The change in free energy (ΔG) that is, the <u>energy available to do work</u>, of a system for a constant-temperature process is:
-
When ΔG < 0 the reaction is spontaneous in the forward direction.
- When ΔG > 0 the reaction is nonspontaneous. The reaction is
spontaneous in the opposite direction.
- When ΔG = 0 the system is at equilibrium.
If <u>both ΔH and ΔS are positive</u>, then ΔG will be negative only when the TΔS term is greater in magnitude than ΔH. This condition is met when T is large.
Answer:
<em></em>
<em></em>
- <em>The halogens posses </em><u><em>seven </em></u><em>valence electrons</em>
Explanation:
- <em>Valence electrons </em>are the electrons in the outermost orbitals of the atoms, which are the orbitals with the highest main energy level (principal quantum number).
- Halogens are the elements of the group 17 of the periodic table: F, Cl, Br, I, At.
- You can tell the number of valence electrons of the representative elements from the number of the group to which they belong. For the representative elements, the number of valence electrons equal the unit digit of the group number.
This table summarizes it:
Group number number of valence electrons
1 1
2 2
13 3
14 4
15 5
16 6
17 7
18 8
- So, in conclusion, <em>the halogens possess 7 valence electrons.</em>
