CHEMISTRY COMMUNITY

Ashley R 1A

for marshmallow 41d) which six atoms can form hydrogen bonds? for this problem, are we supposed to not include the hydrogens that could bind to the lone pairs on other molecules. Or are we supposed to count two lone pairs (like how there's two lone pairs on the double bonded oxygen) as two atoms?

Ashley R 1A

For number 21, how would you find the oxidation state for the central Fe atom, when it should typically only be around +1 to +3, when there are so many negatively charged anions around it?

Ashley R 1A

The question asks how you compare the bond strength of acetic acid CH3COOH to formic acid HCOOH. Why is formic acid a stronger acid? I was going based off of the size and thought that because acetic acid molecule is larger, it would more easily deprotonate.

Ashley R 1A

to add on, if it helps i usually try to think about the strong acids and bases list, and the cations are the same. for example, with strong acids like HCl and HBr, because you know they are already strong acids then you can assume that molecules containing Cl or Br atoms can be categorized as acids.

Ashley R 1A

to add on, if it helps i usually try to think about the strong acids and bases list, and the cations are the same. for example, with strong acids like HCl and HBr, because you know they are already strong acids then you can assume that molecules containing Cl or Br atoms can be categorized as acids.

Ashley R 1A

what's the conceptual reasoning behind why oxoacids are stronger when they have more oxygen atoms? i'm lost about the relationship between the oxidation number of the central atom and the amount of oxygen atoms within a compound.

Ashley R 1A

Hund's rule is also important as it states that each sublevel must have one electron occupying the orbital before the orbital is occupied by 2 electrons. This ensures that hybridization occurs because if hund's rule were not followed, hybridization may not occur if only p orbitals were filled and no...

Ashley R 1A

When orbitals hybridize we get sp, sp2, and sp3 hybridization. How does hybridization affect bond length?

Ashley R 1A

By allowing hybridization to occur, we are thus able to have a full octet when 2s and 2p orbitals hybridize together to an energy state in between s and p orbitals.

Ashley R 1A

I believe that because some of the Nitrogen electrons have s orbitals and some have p orbitals; thus, hybridization is necessary to form a bond between the two orbital types as both electrons from the s and the p orbitals are required for bonding and to make a full valence electron shell of 8 electr...

Ashley R 1A

To add on: London dispersion forces are the weakest of all of these, and are seen in any type of molecule. dipole-dipole interactions are the next strongest interactions and occur between polar molecules, which is determined by a molecule's shape. Hydrogen bonding is the strongest, and occurs when a...

Ashley R 1A

This concept can be applied to the opposite case when we compare CCl 4 with CCl 3 Br Because Br is less electronegative than Cl, the bond angles of the C-Cl bonds will be slightly greater than 109 degrees. Thus, making the CCl 3 Br molecule slightly polar as the individual dipole moments no longer c...

Ashley R 1A

London Dispersion Force (LDF) is a weak intermolecular force caused by the distribution of elections in the electron cloud of atoms. Hence, because all atoms have electron clouds including noble gases, noble gases can have LDF with other atoms. Moreover, whether molecules are polar or non polar, LDF...

Ashley R 1A

Because Hydrogen bonding is between a hydrogen atom (which is partially positive) and either a fluoride, oxygen, or nitrogen atom (which are partially negative) and the difference in electronegativity is more significant than most dipole-dipole interactions, a hydrogen bonds are typically stronger t...

Ashley R 1A

This concept also applies to 5 electron densities.

For 5 electron densities where all 5 are bonds, we have a trigonal bi-pyramidal molecular geometry.
However when we have 4 bonds and 1 unshared electron pair we have a seesaw geometry.

Ashley R 1A

The ones that are set because of the symmetry of the molecule are: linear - 180 trigonal planar - 120 tetrahedral - 109.5 square planar - 90 for the shapes that happen when there's a lone pair on the central atom, to calculate bond angle you are supposed to treat that lone pair as an atom, and then ...

Ashley R 1A

A short cut that might help when calculating formal charge is counting the number of bonds and unpaired electrons and subtracting that number from the number of valence electrons the atom has.

Ashley R 1A

Although molecules can have polar covalent bonds, there are a few exceptions where the dipole moments cancel each other out; thus, creating non-polar molecules that have polar bonds. Ex: CO 2 and CCl 4 While both C=O and C-Cl bonds are polar, the dipole moments cancel each other out due to their lin...

Ashley R 1A

To find the resonance structure that is the "best" or most stable we first look at the number of covalent bonds. The greater the number of bonds, the greater the stability of the structure as more atoms will have a complete octet. Additionally, the structure with the least number of formal...

Ashley R 1A

Boron is also an exception to the octet rule as it can have 6 electrons and be stable. BH₃ is an example of this exception. This occurs because Boron has 3 valence electrons to begin with, and has a stable Formal Charge of 0 when it has three covalent bonds (B-H in this case).

Ashley R 1A

To add on, I like to visualize it by seeing the orbitals within the 2p sub shell. there's 3 orbitals in the 2p sub shell and N has 3 electrons in the 2p sub shell and O has 4. in N, the three electrons each get their own orbital so it's really stable and the electrons don't want to be removed. On th...

Ashley R 1A

To add on to this, if it helps you to visualize it, the equation for electron affinity is the energy of the atom minus the energy of the anion. Therefore, having a positive electron affinity shows that energy is released when an e- is added to an atom. Then, when the electron affinity is negative, i...

Ashley R 1A

To add on, the easiest way I like to remember it is with the amount of protons, since the amount of electrons is the same with these ions. Protons have a positive charge which will draw negatively-charged electrons towards the nucleus, so if an ion has more protons in the nucleus, their radius will ...

Ashley R 1A

Another one is in ionization energy! Generally as you move across a period, the ionization energy should increase. However, the exception is that if there are e- in the same orbital, for atoms right next to each other on the periodic table, it would be easier to remove e- in the same orbital because...

Ashley R 1A

What exactly is the connection between increasing effective nuclear charge (Zeff) and ionization energy increasing across a period? I understand that Zeff increases as you move down, but I'm getting lost on how it's connected to the ionization energy.

Ashley R 1A

Why is the second ionization energy higher than the first for the same atom?

Ashley R 1A

To my understanding, because of the Heisenberg Uncertainty Principle we can never exactly guess where subatomic particles, like electrons, can be located at a given time. Because of this, we use the wave function to give the probability density of an electron at a given point, which basically means ...

Ashley R 1A

Just to add on, this is most important when you are displaying electron configuration. As you are filling the orbitals of a sub shell, you first fill in upwards spinning electrons in each sub shell, denoted as +1/2, and and then you begin filling in the -1/2 downwards spinning electrons after every ...

Ashley R 1A

To add on to the previous response, the wave function is denoted with Ψ and while it actually represents the math function, you are able to get n, l and m(l), the first three quantum numbers, from it.

Ashley R 1A

Regarding your second question reply, l represents the shape inside an energy level, and it represents the orbital angular momentum quantum number. To my understanding, within a hydrogen atom, all the orbitals in a shell will have the same energy despite what shape it has, but this isn't true for at...

Ashley R 1A

for the principal quantum number n, keep in mind that all energies are measured as negative because it's relative to the energy of the free electron. When you start at n=1, this is the first energy level so it will be the lowest and most negative energy level, and as you increase n, energy will subs...

Ashley R 1A

You're going to use the equation E = 1/2 m v^2. In this case, E stands for the kinetic energy of an electron. The mass of an electron will always be constant at 9.109x10^-31 kg, it's on the formula sheet that we're given on tests.

Ashley R 1A

I posted about this question the other day haha :) For part a), you use the e=1/2 m v^2 equation since e = kinetic energy of the electron. You're given velocity, and then the mass of an electron is constant at 9.109 x 10^-31 kg. Then, now that you have e, you can use the equation e = hv to calculate...

Ashley R 1A

Essentially, there is evidence that electromagnetic radiation has "wave-like properties" as you said. The most prevalent evidence is the concept of diffraction, which is when an object is in a light ray's path, it generates patterns of high and low intensities, which causes light to oscill...

Ashley R 1A

Because we have evidence that electromagnetic radiation acts as both a wave (with diffraction/diffraction patterns) and as a particle (photoelectric effect and bohr frequency condition), scientists have accepted the "wave-particle" duality of electromagnetic radiation. This is where the He...

Ashley R 1A

I was going over the online modules for the "Photoelectric Effect" section on the 14A website and came across this problem in the post-module assessment: Light hits a sodium metal surface and the velocity of the ejected electron is 6.61x10^5m/s. The work function for sodium is 150.6 kJ/mol...

Ashley R 1A

molecules are able to be broken down into their individual atoms. on the other hand, formula units are ionic or covalently bonded so they are unable to be broken down any farther. the formula unit for these compounds is just the lowest possible ratio for that compound

Ashley R 1A

for this problem, the question asks specifically how many moles of Cl- ions you have, and because of part a), you already have the moles of the entire molecule. you essentially use dimensional analysis to solve for the number of Cl- ions, so you would multiply the number of CuCl2*4H2O moles (which w...

Ashley R 1A

if you have a scientific calculator, there's a button that converts decimals to fractions and vice versa, it's denoted as F>D on mine. I usually use this to convert the decimal value to a fraction and then just multiply by that denominator.

Ashley R 1A

avogadro's number is used to determine how many "formula units" are in one mole. if you're talking about a molecule, make sure you're using the constant and converting to molecules. Whereas if you have an atom, it's 6.022E23 atoms=1 mole

Ashley R 1A

It should be fine :) The purpose of sig figs is to account for inaccuracies like that anyways, so as long as you show your work we won't get docked points !

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