The energy level is equal to the row number on the periodic table. The n=3 energy level has an s, p, and d orbital. Since there are one, three, and five orbitals, respectively within each of these subshells, there will be a maximum of 18 electrons in the third energy level.

The energy level is equal to the row number on the periodic table. The n=4 energy level has s, p, d, and f subshells. Since there are one, three, five, and seven orbitals, respectively within each of these subshells, there will be a maximum of 32 electrons in the third energy level. Also, we can use the general formula to find the number of electrons in an energy level: . Thus in the fourth energy level there are  electrons.

Each orbital can only hold a maximum of two electrons, going in opposite directions. Don't confuse this with the number of electrons that can be held within a particular energy level, which is given by the following formula:  where  is the energy level.

(a) Octahedral: six charge clouds and six atoms (b) Square planar: six charge clouds and four atoms (c) Trigonal pyramidal: four charge clouds and three atoms (d) Tetrahedral: four charge clouds and four atoms (e) Trigonal bipyramidal: five charge clouds and five atoms

Ideal gas pressure only takes the repulsive forces between gas molecules into consideration. The truth is, gas molecules can also exhibit attractive forces with one another (London dispersion forces). This attractive force pulls the molecules inward and slows their velocity before striking the wall of the container. As a result, real gases exert slightly less pressure compared to the ideal pressure.

use PV = nRT

V = nRT / P  ; must covert T into K

V = (2)(0.0821)(273)/ 1

= 44.8 L

At high pressure and low temperature two things are happening that will cause gases to deviate from ideal behavior.  At low temperature the individual gas molecules are moving slower. As the pressure is increased the individual molecules are being pushed closer to one another.  Thus, when the gas molecules are closer together and moving at reduced speeds they are more likely to interact with one another.  Ideal gas behavior is dependent upon an absence of intermolecular interaction between the gas molecules.  Therefore, the increased likelihood of intermolecular interactions between the gas molecules at increased pressure and decreased temperature is likely to cause gases to deviate from ideal behavior. 

Hydrogen gas is a diatomic gas, so the molecules that are filling the balloon exist as H₂.  Neon since it is a noble gas exists as a monoatomic gas, so the molecules that are filling the neon balloon exist as Ne.  The volumes given allow us to calculate the amount of each gas in moles.  At STP one mole of gas occupies 22.4 L, so there is one mole of hydrogen gas and there are two moles of neon gas.  One mole of hydrogen gas indicates that there are actually two moles of hydrogen atoms in the balloon.  Two moles of neon gas indicates that there are two moles of neon gas present in the balloon because neon exists as a monoatomic gas.  Thus there are two moles of atoms in each balloon.  

An ideal gas is most likely low concentration of identical molecules and low pressure. The molecules move randomly and collisions are completely elastic.

At STP, one mole of an ideal gas occupies 22.4L. You should know this value for the exam.

Another approach would use the ideal gas law: . Since we know that the container is at STP, we know that the container has a temperature of 273.15K and has a pressure of 1atm.

Adding the other known variables, the equation becomes

Solving for n, we find that there is 0.13 moles of hydrogen gas in the container.