CHEMISTRY COMMUNITY

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The roman numeral is equal to the charge on the transition metal.

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There is also a list of common ligands on the class website.

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Cl- is the conjugate base of a strong acid so it is a stable anion. This means it does not affect pH much in the solution, so it is left out of the equilibrium equation.

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When the anion is stable, the forward reaction will occur more often than the reverse reaction because the anion's stability will mean that it is less inclined to bond back to the released proton. This will increase the acidity of the solution.

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Strong acids are acids that dissociate completely. HF does not do this because the HF bond is very short and very strong, so it does not come apart.

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pH measures the concentration of H₃O⁺ ions while pOH measure the concentration of OH^- ions.

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An acid that dissociates more easily (longer bond length) is a stronger acid and will have a higher K_A value.

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Acids are proton donors and bases are proton acceptors.

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The HCl bond is longer than the HF bond. This means that it dissociates more easily than the HF bond, so it is a relatively stronger acid.

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Sigma bonds are the first bonds that form (thus, every bond has a sigma bond). Pi bonds are any bonds that form beyond the first. So, double bonds have one sigma and one pi bond and triple bonds have one sigma and two pi bonds.

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Usually, VSEPR structures are derived from first looking at the Lewis dot structures. When constructing the Lewis dot structure, you should take formal charges into account by trying to minimize them, especially on the central atom.

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Yes, all O atoms have the same electronegativity. CO₂ is considered nonpolar.

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A molecule with stronger IMFs will have a higher boiling point because more heat energy is required to overcome the interactions.

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A VSEPR model is the particular shape a model takes. This is always the same because the shape will always be its most stable form where the electrons are the farthest apart.

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Yes, every compound has London Dispersion Forces due to random electron movement that creates temporary positively charged and temporarily negatively charged regions that lead to electrostatic interactions. The larger the mass of the compounds, the stronger the forces.

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Cations have polarizing power because they can pull electrons.

Anions are polarizable because they have the electrons that are pulled away.

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I think we will need to know them, and Professor Lavelle will probably go over them in class on Friday. The other shapes result when lone pairs (rather than bonding pairs) occupy regions of electron density.

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You should know the bond angles, but you don't necessarily have to memorize them. Understanding the shapes conceptually will allow you to calculate the bond angle.

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The difference in electronegativity of the two elements should be measured by their electronegativity values, not by their physical distance on the periodic table. This is because the periodic table is organized the way it is due to reasons other than electronegativity.

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There are some atoms that have incomplete octets because it makes them more stable or it is in line with the number of bonds they "like" to form. The most common examples are: H is stable with 2 valence electrons. Be is stable with 4 valence electrons. B and Al are stable with 6 valence el...

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Highly distorted electrons are highly polarizable because they can be pulled away from their central atoms towards the bonding region. Ionic bonds display covalent characteristics when electrostatic attraction pulls electrons from the anion towards the cation. The electrons being pulled towards the ...

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Assign double and triple bonds to satisfy the octet rule and reduce formal charge.

It may be helpful to keep in mind that C usually forms four bonds, N usually forms three, and O usually forms two.

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A radical is a molecule whose Lewis Dot Structure has an unpaired valence electron.

This makes it highly reactive, and thus, important to biological processes.

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If formal charges that are not equal to 0 must exist, they should be as symmetrically spaced out on the outer atoms as possible. This increases surface area and makes the molecule more stable because it has lower energy.

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When two different atoms are bonded together, the bond has covalent and ionic characteristics. Ionic bonds (electronegativity difference > 2) have covalent characteristics because the electrostatic attractions of the negative ion towards the positive ion pulls electrons into the bonding region. The ...

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S-block metals are more reactive because they have lower ionization energies than p-block metals. This is because s-block metals have a lower effective nuclear charge than the p-block metals do.

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Kendall 3H wrote:The d subshell of an atom has 5 orbital and can therefore fit 10 electrons, meaning there can be 10 valence electrons rather than only 8.

To add on, it is possible for some molecules to have central atoms with more than 10 electrons. For example, SF₆ has 12 electrons around the central atom.

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a) Mg's preferred oxidation state is +2 while As's preferred oxidation state is -3. To make the molecule neutral, the formula is Mg₃As₂.
b) The (III) after In indicates it has a +3 oxidation state. S's preferred oxidation state is -2. Thus, to make the molecule neutral, the formula is In₂S₃.

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The example had 10 electrons on the central atoms, but there are situations where expanded octets can be even larger.

For example, SF₆ has 12 electrons on the central atoms.

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In addition to the above, keeping in mind that H prefers one bond, O prefers two bonds, N prefers three bonds, and carbon prefers four bonds will help you place double/triple bonds that can contribute to resonance within structures.

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If there is only one electron in each orbital, they have parallel spins. If two electrons are in the same orbital, they must have paired spins.

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When you remove electrons, there is less electron-electron repulsion remaining in the cation. This means every remaining electron is held tighter and is harder to remove.

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When you remove an electron and form a cation, that cation has less electron-electron repulsion. This allows the remaining valence electrons to be held tighter by the nucleus, making them harder to remove.

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Even though removing a second electron would give those atoms a full octet, remember that the cation formed from removing the first electron has less electron-electron repulsion so the remaining single electron in the valence shell is held tighter by the nucleus. This makes it harder to pull off, so...

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I think we definitely need to know how to describe an electron that is in a p orbital (i.e. be able to write/draw an electron configuration or write quantum numbers for a given electron. If we need to draw p-orbitals, just remember that they are petal-shaped and that the three p-orbitals are always ...

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It makes sense that O would have a lower first ionization energy than F because we know that ionization energy increases from left to right across a period. O has a lower ionization energy than N because O is the first element to have a paired electron in the 2p orbital. This creates extra electron-...

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a) n=2, l=1 represents the 2p subshell, which would have three orbitals. b) n=4, l=2, m l =2 represents a specific orbital in the 4d subshell, so only one orbital could have these numbers. c) n=2 represents 2s and 2p, which would have a total of four orbitals. d) n=3, l=2, m l =1 represents a specif...

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s, p, d, and f are generally considered subshells, not orbitals. Each subshell then contains orbitals within it.

For example, the s subshell contains one orbital while the p subshell contains three (p_x, p_y, and p_z) orbitals.

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I am still confused about how to calculate the magnetic quantum number (ml) based on the principal quantum number (n) and angular momentum number( l ). Could someone please explain to me the process of finding it? Like I know that (l) is dependent on (n) but the (ml) still confuses me. m l is the m...

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l represents the angular momentum quantum number. It represents shape and tells you which subshell the electron is in. Its values can range from 0 to n-1. 0 - s subshell 1 - p subshell 2 - d subshell 3 - f subshell ... As for radius, when n increases, the radius of the atom also increases because th...

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n is the principal quantum number that represents energy. Its values can be anything greater than one. l is the angular momentum quantum number, and it describes shape. Its values can be anything from 0 to n-1. 0 represents the s subshell. 1 represents the p subshell. 2 represents the d subshell. 3 ...

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Absorption of a photon will excite electrons to a higher energy level only if the photon contains enough energy to move electrons to energy levels beyond their ground state.

When the electrons drop back down to their ground state, a photon will be emitted.

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In the Balmer series, electrons end at n=2. Because the drop from higher energy levels to n=2 is not as large as the drop to n=1, comparatively less energy is emitted. This is why the emitted light is in the visible spectrum. In the Lyman series, electrons end at n=1. The drop to n=1 from n=2 (or n>...

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E = hv
E = (6.626*10^-34 J*s) x (3.00*10¹⁵ Hz)
E = 1.99*10^-18 J

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A photon is a packet of energy, representing a way in which light acts as a particle.

A photon carries energy proportional to its frequency and has zero mass.

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A higher intensity light means there is an increased number of photons. It does not mean that each photon has more energy. Rather, whenever you increase the light intensity, there are just more photons of the initial energy/wavelength/frequency. This means that the kinetic energy of each electron em...

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We are usually given the percent mass of an element when we need to figure out the empirical formula of a compound. It is important to note here that the exact mass of the compound or element here then does not matter; all that matters is the ratio of elements to each other. We assume 100. grams sim...

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The Law of Conservation of Mass says that mass cannot be created or destroyed during chemical reactions. This means there must be an equal number of atoms before and after the chemical reactions. This means that if an equation is not balanced, it's not a real chemical reaction that could occur. We n...

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To find the metal in M(OH)_s, you should subtract the molar mass of (OH)₂ from the molar mass of the whole molecule.

The mass of (OH)₂ = (15.999 g/mol + 1.008 g/mol) * 2 = 34.014 g/mol.

Then to find the metal: 74.10 g/mol - 34.014 g/mol = 40.09 g/mol, which is closest to the molar mass of Ca.

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When doing these problems it is best not to round after each step. Instead, just input the answer given on your calculator into the next line and go from there. At the end of the problem, apply the sig fig rules to the final answer. Make sure to keep track of the proper number of sig figs at every s...

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Tin is one of the transition metals on the periodic table. This means that it has multiple oxidation states. For tin specifically, the oxidations states are +2 or +4. When naming molecules containing transition metals, a roman numeral is often placed after the transitional metal to denote the oxidat...

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