WHY?
1- Natural systems left to themselves move towards states of lower potential energy.?
————————————————————————————————————————————————————————————————————————————————————————————————————
2- Lower energy configurations of elements happen when the elements get an electronic configuration similar to the nearest inert gas.?
————————————————————————————————————————————————————————————————————————————————————————————————————
3- Lithium and sodium would tend to “lose” one electron.?
————————————————————————————————————————————————————————————————————————————————————————————————————
4- When similar atoms such as H or O or N come together they can gain stability by sharing electrons in a covalent bond.?
————————————————————————————————————————————————————————————————————————————————————————————————————
5- Nitrogen, hydrogen and oxygen atoms go to more stable configurations by forming the diatomic gases, N2, H2, and O2 respectively rather than remain in the atomic form.?
————————————————————————————————————————————————————————————————————————————————————————————————————
6- To change the state of a system from lower to higher potential energy, one must therefore supply energy to the system. Why?
————————————————————————————————————————————————————————————————————————————————————————————————————
7- Hydrogen and oxygen combine to form water. Which is more stable — hydrogen and oxygen gas separately, or in combination as water and why?
————————————————————————————————————————————————————————————————————————————————————————————————————
8- In each of the following reactions:
– Name the product.
– Balance the reaction.
– Write the moles of each component.
– Say whether the reaction is endothermic or exothermic.
– Say whether the system is stable before or after the reaction.
| Reaction | Heat of Reaction (kcal/mole) |
| 1. H2 + O2 H2O | -58.5 |
| 2. N2 + O2 NO2 | +21.6 |
| 3. C +H2 C2H6 | -20.2 |
| 4. C + H2 C3H8 | -24.8 |
| 5. N2 + H2 NH3 | -11.0 |
Good Luck
Dr. Kawkab Al-Naimi