CHEMISTRY COMMUNITY

Melvin Reputana 1L

I would like to add that in oxoacids, when stabilization occurs, the negative charge around the molecule is delocalized which weakens the attraction between O-H. This creates a stronger acid because the H+ is more likely to break off.

Melvin Reputana 1L

You would identify spectator ions by writing the complete ionic equation and determining which ions appear in both the products and reactants side. If they appear in both sides, then it means that they do not participate in the reaction and are just spectators.

Melvin Reputana 1L

All the ligands in the "Ligand Names in Coordination Compounds" chart Dr. Lavelle sent should be memorized.

Melvin Reputana 1L

There is also a difference between amphoteric compounds and amphiprotic compunds. Amphoteric compounds can act as an acid or a base, while amphiprotic compounds can donate and accept electron pairs. Basically, all amphiprotic compunds can be amphoteric, but not all amphoteric compounds can be amphip...

Melvin Reputana 1L

I went through the problem by first finding which ion in the salt would come from a weak acid/base. If both ions come from a strong acid and strong base, then the solution would remain neutral. However, if the ion came from a weak base, then the pH of the solution will be less than 7 (acidic) becaus...

Melvin Reputana 1L

The chart is on the left side of page 450 in the textbook. It is called Figure 6A.7.

Melvin Reputana 1L

Acidic oxides are commonly molecular compounds, while basic oxides are usually ionic compounds. Therefore, for this problem, SO3 is a molecular compound which means that it is an acidic oxide.

Melvin Reputana 1L

Hybridization does not arise solely from electron promotion. It can still arise without it such as in ammonia (NH3) where Nitrogen has 5 valence electrons with all its p orbitals filled with one electron. You would find that there would be four sp3 orbitals; however, three of them only have one elec...

Melvin Reputana 1L

Another way to look at this is the trend for binary acids within the same group is bond strength. A weaker(longer) bond between the anion and H allows for easier removal of H+ which means that it is a stronger acid because it can dissociate more in water. HF is a weak acid because H-F is a short, st...

Melvin Reputana 1L

You should also consider what polydentates are and some common examples are ethylenediamine(en) = bidentate, ethylenediaminetetraacetato (edta) = hexadentate, and carbonate = mono- or bidentate.

Melvin Reputana 1L

To answer your third question, one of the naming rules for a coordination compound is that if the overall complex has a negative charge, then you add the suffix -ate to the end of the metal's name. This causes some issues for some metals like iron, where you would use the name ferrate (from Iron's l...

Melvin Reputana 1L

In terms of the Lewis definition, the acid is an electron pair acceptor. On the other hand, according to the Bronsted-Lowry definition, the compound that donates a proton is the acid. For both definitions, the base is the compound that accepts a proton.

Melvin Reputana 1L

You can determine the shape of a coordination compound by determining the coordination number of the central atom which is the metal atom/ion. A coordination compound with a coordination number of 4 would usually have a tetrahederal geometry. A square planar geometry is also possible with a coordina...

Melvin Reputana 1L

In terms of the Lewis definition, the proton is an acid. On the other hand, according to the Bronsted-Lowry definition, the compound that donates the proton is the acid. For both definitions, the base is the compound that accepts a proton.

Melvin Reputana 1L

It is also important to know that intramolecular forces are stronger than intermolecular forces because they involve the actual sharing/transfer of electrons that bond atoms together.

Melvin Reputana 1L

I would also like to add on that the Arrhenius definition involves acids/bases being dissolved in water, while the Bronsted-Lowry definition considers how acids/bases can be dissolved in other solvents besides water.

Melvin Reputana 1L

It also good to note that the Bronsted-lowry definition of an acid/base accounts for how acids/bases can be dissolved in solvents other than water such as ammonia. The Arrhenius definition involves H+ and OH- ions which occur due to the acid/base being dissolved in water.

Melvin Reputana 1L

You would determine if a compound is an acid or base based on the reaction in which you would use either the bronsted-lowry or lewis definition of an acid/ base. Bronsted-lowry acid: proton donor Bronsted-lowry base: proton acceptor Lewis acid: electron pair acceptor Lewis base: electron pair donor ...

Melvin Reputana 1L

Boron is one of the exceptions of the octet rule in which it likes to form three bonds. Therefore, it is possible for the Lewis structure to not follow the octet rule. When it comes to determining the hybridization, you would just follow normal procedures and count the amount of electron dense regio...

Melvin Reputana 1L

I would also like to add on that a good rule to follow is that in a tetrahedral, when all the terminal atoms are not the same, then the molecule is most likely polar. Even though, CBr2Cl2 looks like it is nonpolar, you also need to consider that terminal atoms are not exactly opposite from each othe...

Melvin Reputana 1L

When dealing with large molecules, we would consider the local geometry. For example, in long carbon chains, this means that we would break the chain into pieces with each carbon atom in the center region act as a central atom and form their own shape.

Melvin Reputana 1L

When finding the molecular shape, you only consider the number of atoms. However, you would first need to figure out the electron arrangement of the molecule which does take into account both the lone pairs and the number of atoms which are basically all the regions of electron density. From there, ...

Melvin Reputana 1L

All single covalent bonds are sigma bonds. When it comes to double and triple bonds, pi bonds are introduced,including the one sigma bond, with a double bond having one pi bond + one sigma bond and a triple bond having two pi bonds + one sigma bond. Also note that sigma bonds form when two 1s orbita...

Melvin Reputana 1L

Assigning formal charges helps you determine the best lewis structure for a molecule by assuming that electrons are shared equally between elements, regardless of electronegativity. This helps when different resonance structures are possible as the dominant structure would be the one with the lowest...

Melvin Reputana 1L

There is a dipole-dipole interaction on NH2OH because the electrons within the molecule are unequally shared. There is a nitrogen atom and oxygen atom that have higher electronegativities than hydrogen which means that the electrons would be pulled closer to these atoms. A good indicator if a molecu...

Melvin Reputana 1L

We're not expected to know the exact electronegativity values, instead we should know the periodic trend for electronegativity which follows the same trends as ionization energy and electron affinity. Also, the questions we'll be given will probably make the electronegativity differences between two...

Melvin Reputana 1L

I also believe that is the most straight forward way. I think a good way to help you process limiting reagent problems is to list what you're given and what you're trying to find. Then compare to see which reactant produces the least amount of product which means that specific reactant is what's lim...

Melvin Reputana 1L

Here is a website that helps you experiment with the VSEPR models:

https://phet.colorado.edu/en/simulation/molecule-shapes

It can help you visualize how the shapes are formed and how the presence of lone pairs can alter the geometry.

Melvin Reputana 1L

The first ionization energy of oxygen is lower than the first ionization energy of nitrogen because the repulsive force of electrons in oxygen are stronger than the effective nuclear charge of oxygen. As a result, the first ionization of oxygen is lower as it it is easier to remove the electrons on ...

Melvin Reputana 1L

I would also like to add on that the presence of lone pairs creates repulsion forces between electrons. There are repulsion forces already present in the molecule, between the bonding pairs of electrons of the atoms. However, lone pairs express stronger repulsion forces. This greater force is what p...

Melvin Reputana 1L

From the textbook, it describes an anion being highly polarizable if it is large. On other hand, a cation is expected to have high polarizing power based on how small it is and if it is highly charged. Does the charge of an anion also matter for polarizability?

Melvin Reputana 1L

In order to decide which electrons are removed, I would write the ground-state electron configuration of the regular atom. Then I would remove electrons from the last orbital that has the highest energy level because it is the furthest away from the nucleus. I think this is where Dr. Lavelle's sugge...

Melvin Reputana 1L

I would also like to add on that electronegativity is a calculated value based on the values of electron affinity and ionization energy which is why it has the same trends.

Melvin Reputana 1L

You do not need to know the values for electronegativity. However, you should know the trends for electronegativity which follows the same trends as ionization energy and electron affinity. This is reasonable because electronegativity is calculated based on the values of ionization energy and electr...

Melvin Reputana 1L

Phosphorus is in the third period of the Periodic table. P-block elements in the third period and in later periods have access to the d-orbital which allows such elements to expand their valence shells. This is due to how these elements have empty d-orbitals in their valence shell.

Melvin Reputana 1L

In part c of 2B.1, we are asked to draw the lewis structure of ONF which has 18 electrons. One lone pair goes on the central atom which is Nitrogen. However, the formal charge of nitrogen was not zero, so I made a double bond between O and N which allowed the formal charge of nitrogen and oxygen to ...

Melvin Reputana 1L

Yes, they have the same number of electrons; however, each ion's atomic number is different. This causes varying effective nuclear charges within each ion. For example, for the chlorine ion, the nuclear charge is greater compared to the phosphorus ion and sulfur ion. Despite having the same number o...

Melvin Reputana 1L

Q: What do you call a tooth in a glass of water?
A: A one molar solution.

Melvin Reputana 1L

Both ways are technically correct. However, it is more accurate to order the electron configuration with the n's being kept together because the d-orbital is at a lower energy level. This will be useful when finding out where electrons would be removed from because you would see that the electrons w...

Melvin Reputana 1L

When drawing the orbital box diagram of an atom, an unpaired electron in an orbital would have a spin that is represented by an up arrow correct? Can it ever be a down arrow first?

Melvin Reputana 1L

All quantum objects, ex: photons and electrons, exhibit wave-like and particle-like properties. However, what distinguishes a photon from a particle is that a photon has zero rest mass compared to a particle. Photons also carry no electromagnetic charge compared to an electron which is negatively ch...

Melvin Reputana 1L

During lecture today, Dr. Lavelle described the variable "r" in Coulomb's law as the distance between charges. In high school, I was told that it was the atomic radius. Would both descriptions be an accurate description of what "r" is?

Melvin Reputana 1L

I also want to add on that the Heisenberg Uncertainty Principle arises from how the measurement process of finding the position or momentum can influence the outcome of the other. This essentially limits how accurate both the momentum and position of a particle will measured. The equation is a quant...

Melvin Reputana 1L

I would also like to add on that the relationship between Schrodinger's Equation and the wavefunction comes from how the wavefunction can be found by solving the Schrodinger equation for a particle. This is based on the Born Interpretation which states that the probability of finding the particle in...

Melvin Reputana 1L

Just like what the others have said, the De Broglie equation is used for any moving particle with momentum, p, which is mass * velocity. When reading a problem, I think a good indicator for using the De Broglie Equation would be when you're given the velocity and the mass of the object and you're as...

Melvin Reputana 1L

From the most recent lecture, Dr. Lavelle explained that we cannot use the standard equations for light, (\lambda v = c) and (E = hv) , with electrons. Instead, we can use the De Broglie Equation. But the derivation of the De Broglie equation comes from both of these equations. Is th...

Melvin Reputana 1L

I just finished the module explaining the wave properties of electrons. I need some clarification on constructive interference and destructive interference. How does each type interference affect the outcome of the diffraction pattern? Does the energy of the resulting wave have a correlation with th...

Melvin Reputana 1L

Avogadro’s constant is derived by finding the exact number of atoms in exactly 12 grams of carbon-12. Avogadro’s number is used to describe the number of objects per mole. These objects can be atoms, molecules, or ions. You should use Avogadro’s number when determining the number of these objects, o...

Melvin Reputana 1L

I understand that frequency is essentially the number of times a point on the wave passes a fixed area in one second. However, how can you manipulate the frequency of a wave? Is it by increasing the intensity of the light?

Melvin Reputana 1L

Hello can someone please help me understand what catalysts are and how they work? I understand that catalysts do not participate in a chemical reaction. However, for example in H.7, how does the copper metal help drive the reaction without interacting with the reactants?

Melvin Reputana 1L

I am having trouble understanding the logic behind solving part B of F.1. To start part B, I calculated the molar mass of Citral using its molecular formula which is C_{10}H_{16}O However, when it comes to determining the mass percentage composition of each component, I was told that I can multiply ...

Melvin Reputana 1L

The reason why 288 pm was used instead of the given 144 pm was because that was radius of each atom. In order to get the whole size of the atom, you have to get the diameter of the atom which would be double the radius. Therefore, the value 288 pm was used in order calculate the total distance.

Melvin Reputana 1L

Here are some rules about significant figures: 1) Non-zero numbers are always significant (ex: 72.3 = 3 significant figures) 2) Zeroes between non-zero numbers are always significant (ex: 60.5 = 3 significant figures) 3) Zeroes at the end of a number and to the right of a decimal are significant. Th...

Melvin Reputana 1L

When writing net ionic equations, you would have to write out all the ions in the reaction first. To do this, you would have to use solubility rules to determine which compounds dissociate in water. In this problem, both Copper (II) Nitrate and Sodium Hydroxide dissociate in water. Therefore, for th...

Melvin Reputana 1L

How should I work through problems with polyatomic ions? Should I write out each kind of atom in the reaction or should I consider the polyatomic ion as a whole when balancing?

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