Iridium-192 is used in cancer treatment, a small cylindrical piece of 192 Ir, 0.6 mm in diameter (0.3mm radius) and 3.5 mm long, is surgically inserted into the tumor. if the density of iridium is 22.42 g/cm3, how many iridium atoms are present in the sample?
Let us start by computing for the volume of the cylinder. V = π(r^2)*h where r and h are the radius and height of the cylinder, respectively. Let's convert all given dimensions to cm first. Radius = 0.03 cm, height is 0.35cm long.
V = π * (0.03cm)^2 * 0.35 cm = 9.896*10^-4 cm^3
Now we have the volume of 192-Ir, let's use the density provided to get it's mass, and once we have the mass let's use the molar mass to get the amount of moles. After getting the amount of moles, we use Avogadro's number to convert moles into number of atoms. See the calculation below and see if all units "cancel":
9.896*10^-4 cm^3 * (22.42 g/cm3) * (1 mole / 191.963 g) * (6.022x10^23 atoms /mole)
= 6.96 x 10^19 atoms of Ir-122 are present.
Answer:
5
Explanation:
A lithium atom with an atomic number of 3 and a charge of -2 will have a total number of electrons.
The atomic number is the number of protons in an atom. For a neutral atom that has not gained or lost electrons, the atomic number is the same as the number of electrons.
neutral atom: atomic number of electrons
For neutral atom of lithium, we will have 3 electrons
Now, lithium with a charge of -2 has gained two more electrons to the original 3 this now makes it 5.
ii.
It is an anion because it is negatively charged.
Negatively charged particles are called anion.
Gases, bc its expand the most upon heating because the intermolecular space is more than in solids or liquids.
intermolecular space = the space between each particles
Answer:
Mass of the water is equal to the mass of ice
Explanation:
When ice melts, the mass remains the same even though its volume decreases leading to a decrease in density of water.
The mass remains the same because according to the law of conservation of mass, mass can neither be created nor destroyed. Since mass is neither created nor destroyed in the process of melting, the mass of water must remain the same.
