An element with mass number 81 contains 31.7% more neutros as compared to protons Assign the atomic symbol.

Who showed that the atomic number of an element is a more fundamental property than its atomic mass and when?

Atomic number of Mg is 12 and its mass number is 24. How many protons and electrons does a Mg^2+ ion have?

Explain briefly how +2 state becomes more and more stable in the first half of the first row transition elements with increasing atomic number?

A hydrocarbon was found to contain approximately 75% carbon and 25% hydrogen by mass. Calculate the empirical formula of the hydrocarbon, assuming relative atomic masses of carbon and hydrogen as 12 and 1.

Estimate the average mass density of a sodium atom assuming its size to be about 2.5 A- (Use the known values of Avogadro’s number and the atomic mass of sodium). Compare it with the density of sodium in its crystalline phase: 970 kg m^(-3) . Are the two densities of the same order of magnitude? If so, why

The unit of length convenient on the nuclear scale is a fermi : 1 f = 10^(-15) m. Nuclear sizes obey roughly the following empirical relation : r = r_0A^(1/3) where r is the radius of the nucleus, A its mass number, and r_0 is a constant equal to about, 1.2 f. Show that the rule implies that nuclear mass density is nearly constant for different nuclei. Estimate the mass density of sodium nucleus. Compare it with the average mass density of a sodium atom obtained in Exercise. 2.27.

An atom has electronic configuration 2,8,7. What is the atomic number of this element?