What characteristic of an atom is changing in nuclear reactions? nucleus of an atom O electron size of atom O shape of atom

(a) An aspiring physicist wants to build a scale model of a hydrogen atom for her science fair project. If the atom is 1.00 m in diameter, how big should she try to make the nucleus? (b) How easy will this be to do?

Integrated Concepts Estimate the density of a nucleus by calculating the density of a proton, taking it to be a sphere 1.2 fm in diameter. Compare your result with the value estimated in this chapter.

Unreasonable Results The relatively scarce naturally occurring calcium isotope 48Ca has a halflife at about 21016y. (a) A small sample of this isotope is labeled as having an activity of 1.0 Ci. What is the mass of the 48Ca in the sample? (b) What is unreasonable about this result? (c) What assumption is responsible?

Data from the appendices and the periodic table may be needed for these problems. (a) Natural potassium contains 40K, which has a halflife of 1.277109y. What mass of 40K in a person would have a decay rate of 4140 Bq? (b) What is the fraction of 40K in natural potassium, given that the person has 140 g in his body? (These numbers are typical for a 70kg adult.)

Suppose a particle of ionizing radiation deposits 1.0 MeV in the gas of a Geiger tube, all of which goes to creating ion pairs. Each ion pair requires 30.0 eV of energy. (a) The applied voltage sweeps the ions out of the gas in 1.00 (s. What is the current? (b) This current is smaller than the actual current since the applied voltage in the Geiger tube accelerates the separated ions, which then create ether ion pairs in subsequent collisions. What is the current if this last effect multiplies the number of ion pairs by 900?

An old campfire is uncovered during an archaeological dig. Its charcoal is found to contain less than 1.1000 the normal amount of 14C. Estimate the minimum age of the charcoal, noting that 210 = 1024.

To obtain the most precise value of BE from the equation BE=[ZM(1H)+Nmn]c2m(AX)c2, we should take into account the binding energy of the electrons in the neutral atoms. Will doing this produce a larger or smaller value for BE? Why is this effect usually negligible?

Why is the number of neutrons greater than the number of protons in stable nuclei that have an A greater than about 40? Why is this effect more pronounced for the heaviest nuclei?

Data from the appendices and the periodic table may be needed for these problems. 53. You can sometimes find deep red crystal vases in antique stores, called uranium glass because their color was produced by doping the glass with uranium. Look up the natural isotopes of uranium and their halflives, and calculate the activity of such a vase assuming it has 2.00 g of uranium in it. Neglect the activity of any daughter nuclides.