Answer:
They must have the same number of protons.
Explanation:
Protons determine the identity of an element. However, the neutrons can vary, resulting in different masses.
Answer:
In Dobereiner’s triads, elements were placed :
- According to increasing order of their atomic masses.
- Into groups which have similar chemical and physical properties.
- In each group there were three elements.
In Modern periodic table, elements are placed:
- According to increasing order of their atomic numbers.
- Into groups and these groups are assigned according to the numbers of valence electrons present in their valence shell.
Aspects of Dobereiner’s triads agreed with the modern periodic table
- Element of the same group will have similar chemical and physical properties.
Disagreement with the modern periodic table.
- Not all groups obeyed law of triads.
- On the basis of properties all known elements could not be classified into groups of triads.
Answer:
4.419 g
Explanation:
55 years is 5.5 half lives
200 g * (1/2)^5.5 = 4.419 g
Answer is: <span> </span>ΔG for <span>methylamine is 18.85 kJ/mol.
</span>ΔG = R·T·lnK.
ΔG is Gibbs energy.
<span>T is the temperature on the Kelvin scale.
R is </span><span>ideal gas constant.
R = 8.314 J/mol</span>·K.
T = 25°C = 293.15 K.
Kb = 0.00044.
ΔG = - 8.314 J/mol·K · 293.15 K · ln(0.00044).
ΔG = 18836.85 J = 18.84 kJ.
