Dobereiner's triads were an early attempt to sort the elements into some logical order by their physical properties. The appearance and reactions of the elements in a triad were similar to each other. He showed that in each triad the mean of the lightest and heaviest atomic weights approximated the atomic weight of the middle element.
Answer:
D. They have the same number of valence electrons
Explanation:
- The periodic table arranges elements into rows known as periods and columns known as groups or families.
- Elements in the same group share similar chemical properties.
- Additionally, they have the same number of valence electrons. For example, elements in group I have one valence electrons while those in group II have two valence electrons.
- Elements in the same period share similar features such as having the same number of energy levels. For example elements in period 4 have four energy levels.
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The Mesosphere, like the troposphere layer, has a decrease in temperature with altitude because of the decreases in the density of the air molecules. Thermosphere: As the altitude increases, the air temperature increases.
690 Kelvin is the boiling point of this compound.
Explanation:
Enthalpy is the sum of internal energy and the product of pressure and volume that is how much energy is in the substance.
Entropy is the measurement of randomness and measure of thermal energy per unit of temperature.
ΔH vap of compound is 46.55 kJ⋅ mol− or J.MOL-1
ΔS vap is 67.37 J⋅mol−1⋅K−1.
The boiling point or temperature can be calculated by the formula:
T= 
T =
= 690 Kelvin
The boiling point is the temperature when atmospheric temperature gets equal to
