CHEMISTRY COMMUNITY

Jenna Ortiguerra 4G

I'm having trouble understanding what chelation is. What is chelation and how exactly does it play a role in coordination compounds?

Jenna Ortiguerra 4G

When determining which molecules are more acidic, in what instances do you use electronegativity vs. atomic radius vs. resonance vs. induction?

Jenna Ortiguerra 4G

Hybridization is the concept of mixing atomic orbitals (s, p, etc.) to form a new set of orbitals (sp, sp2, etc.) An easy was of finding the hybridization of a molecule is by looking at the central atom and seeing how many region of electron density are surrounding the atom. Typically, an atom with ...

Jenna Ortiguerra 4G

An amphiprotic substance is a substance that is capable of both donating protons (hydrogen ions) and accepting them. A compound that is amphoteric has both acid and base character, thus, allowing it to act as either an acid or a base.

Jenna Ortiguerra 4G

I am currently at the review session named “Ionic/intermolecular forces, coordination compounds” from 5-6 and yes, the UA said that he wanted to just focus on intermolecular forces, which is unfortunate because it’s the only session on coordination compounds. I would recommend going to a step-up ses...

Jenna Ortiguerra 4G

CH2BR2 is a polar molecule because its dipole moments do not cancel out so it has a non-zero net moment.

Jenna Ortiguerra 4G

An easy way to think of it is that Bronsted acid/bases have to do with protons and Lewis acids/bases have to do with electron pairs. Bronsted acids are proton donors, while Bronsted bases are proton acceptors. Lewis acids are electron pair acceptors, while Lewis bases are electron pair donors.

Jenna Ortiguerra 4G

Because HCO3^- receives a proton (H+) from water, it serves as a proton acceptor and thus, acts as a base.

Jenna Ortiguerra 4G

A bronsted acid is a proton donor, so it loses H+. A bronsted base is proton acceptor, so it accepts H+.

Jenna Ortiguerra 4G

A single bond is one sigma, double bonds have one sigma and one pi, and triple bonds have one sigma and two pi. An example you can think about is CO2 where both oxygens are double bonded to carbon, so there would be two sigmas and two pis.

Jenna Ortiguerra 4G

A molecule has a tetrahedral shape when the central atom is bonded to four atoms and has no lone pairs (bond angle is 109.5 degrees). A trigonal pyramidal molecule has a central atom that has one lone pair and is bonded to three atoms (the lone pair causes repulsion, causing the angle to be slightly...

Jenna Ortiguerra 4G

Nonpolar molecules have zero dipole moment while polar molecules have a nonzero dipole moment. CCl2H2 is polar because the difference in electronegativity between Cl and H are different which creates a difference in dipole moment between the central atom, making it nonzero.

Jenna Ortiguerra 4G

There is a connection between boiling points and IMF strength. The stronger the IMF, the more energy required to break the bond, thus, requiring more heat. In essence, the stronger the IMF interaction, the higher the boiling point.

Jenna Ortiguerra 4G

A linear molecule has an angle of 180 degrees because it is just a straight line between the three atoms. Bent molecules typically have a lone pair, causing repulsion between the bonded atoms, ultimately forming a smaller angle between the bonded atoms. AX2 and AX2E3 are both linear molecules, with ...

Jenna Ortiguerra 4G

The increasing strength of the intermolecular forces can be seen through: induced dipole-induced dipole < dipole-induced dipole < dipole-dipole < hydrogen bond (hydrogen bonding is a stronger form of dipole bonding because it requires a highly electronegative element (F, O, N) with hydrogen, therefo...

Jenna Ortiguerra 4G

What is an easy way to memorize/calculate bond angles of a molecule using the shape of their lewis structure?

Jenna Ortiguerra 4G

Molecules with 2 bonded pairs will either form a linear and bent shaped molecule. When the central atom has no lone pairs and has equal bonds between its neighboring atoms that are the same, it will have a linear shape.

Jenna Ortiguerra 4G

ClO2+ is trigonal planar because there are two atoms, O, attached to the central atom, Cl. It is angular (also known as bent) because of the lone pair on Cl, which produces repulsion, resulting in a bent shape.

Jenna Ortiguerra 4G

Electronegativity increases from left to right and as you go up the periodic table, with fluorine being the most electronegative element. Electronegativity is the ability of an atom to attract electrons. These atoms have increasing electronegativity because they are closer to filling their valence s...

Jenna Ortiguerra 4G

A single bond is one sigma. A double bond is one sigma and one pi. A triple bond is one sigma and two pi. As an example, think about CO2 where both oxygens are double bonded to carbon. In CO2, there are two sigmas and two pis.

Jenna Ortiguerra 4G

A shortcut that I use to find formal charge is to find the amount of valence electrons an element has. Then you would draw the Lewis of the compound. To find the formal charge of an element, you would count each bond (essentially each line) as 1, and each lone pair (essentially each dot) as one, the...

Jenna Ortiguerra 4G

Yes, higher electronegative atoms tend to draw more electrons to them because the higher the electronegativity, the greater tendency the atom is to attract electrons. This is why electronegativity increases from left to right, and the higher it is on the periodic table (these atoms are usually close...

Jenna Ortiguerra 4G

The ionization of nitrogen is higher than that of oxygen because nitrogen has three of its 2-p subshells half-filled while oxygen has two unpaired electrons, making nitrogen more stable compared to oxygen. Because of this, it is easier to remove electrons from oxygen which means it has a lower ioniz...

Jenna Ortiguerra 4G

The maximum number of electrons in the d-shell is 10. For the d-shell, l=2 so the magnetic quantum numbers are -2, -1, 0, 1, and 2. This means there are 5 subshells and since 2 electrons can fit in each subshell, there can be a max of 10 electrons in the d-orbital.

Jenna Ortiguerra 4G

To convert 4.89x10^-17 J to kJ/mol, you would indeed multiply by 0.001 to convert fromJ to kJ, which would leave you with kJ. If you divide by avogardo's number, it would cancel out the kJ which would leave you with moles.

Jenna Ortiguerra 4G

Can somebody give me a concise summary on the periodic trends, with which ones we need to memorize and the trends they follow on the periodic table?

Jenna Ortiguerra 4G

It is easier to tell which atom has the lowest ionization energy through periodic trends. Typically, ionization energy increases the higher the period and as you go from left to right on the periodic table.

Jenna Ortiguerra 4G

Typically, ionization energy increases the higher the period and as you go from left to right on the periodic table. Na is in the 3s orbital, while Al is on the 3p orbital, which is why Al has a higher ionization energy.

Jenna Ortiguerra 4G

S-blocks are typically more reactive than p-block metals as s-blocks are more on the left of the periodic table, meaning that the ionization of the s-block is lower. This is because as move across a period in the periodic table from left to right, ionization energy generally increases. Since the s-b...

Jenna Ortiguerra 4G

According to our textbook, ionic radius is the shared distance between neighboring ions in an ionic solid; atomic radius is half the distance between the centers of neighboring atoms. Generally, ionic radius and atomic radius do follow the same trends, in which as you go down a group and go from rig...

Jenna Ortiguerra 4G

Question 1E.7 asks to determine whether each of the following electron configurations represents the ground state or an excited state of the atom given. The question gives diagrams of the four electron configurations. I was wondering how do you distinguish between a ground state and an excited state...

Jenna Ortiguerra 4G

There are 7 valence electrons in manganese, with 5 valence electrons coming from the 3d orbital (since the question asks you to include d electrons) and 2 valence electrons coming from the 4s orbital.

Jenna Ortiguerra 4G

Correct, electron affinity is the energy released when an electron is added. Electron affinity fits the trend in which it increases as you go up and across the period on the periodic table because these atoms have a stronger attraction between the nucleus and its electrons, thus more energy is relea...

Jenna Ortiguerra 4G

Electronegativity is the tendency of an atom to attract a shared pair of electrons. Electronegativity increases as you go up and across the period of the periodic table (fluorine is the most electronegative element). Ionization energy is the energy required to remove an electron from an atom or ion....

Jenna Ortiguerra 4G

S-blocks are typically more reactive than p-block metals because as you move across a period in the periodic table, ionization energy increases. The s-block is more on the left of the periodic table compared to p-blocks so the ionization energy of the s-block is lower, which means that it is easier ...

Jenna Ortiguerra 4G

In the ultraviolet spectrum of atomic hydrogen, a line is observed at 102.6 nm. Determine the values of n for the initial and final energy levels of the electron during the emission of energy that leads to this spectral line. I was looking at the solution manual and had trouble interpreting how to g...

Jenna Ortiguerra 4G

Photons are considered particles of light and are unique in which they're both a particle and a wave. Therefore, between a photon and a particle, a photon would be more specific, as a particle is more vast, defined by it's small size and several physical/chemical properties.

Jenna Ortiguerra 4G

Joules in Planck's Constant can either be expressed by 6.626 x 10^-34 J.S. or 6.636 * 10^-34 kg*m^2*s^-1. Typically, choosing between 6.636 * 10^-34 kg*m^2*s^-1 and 6.626 x 10^-34 J.S. is situational, in which the one that would provide the easiest cancellations would be the best option to use.

Jenna Ortiguerra 4G

A quanta is the smallest possible measurement of something, typically energy; while a photon is a quantum measurement of light. The energy of a photon can be expressed in eV (electronvolt) and J (joule).

Jenna Ortiguerra 4G

I typically make a conversion table, similar to the one I would use for a stoichiometry problem to make unit conversions. 1nm = 1x10^-9m, 1m= 1x10^12 1nm x ((1x10^-9m)/(1000nm)) x ((1m)/(1m)) = 1000 pm Thus, 1nm=1000pm Alternatively, when converting from nm to pm, you can move the decimal of the num...

Jenna Ortiguerra 4G

1B. 21 I am having trouble with how to approach this problem. A baseball must weigh between 5.00 and 5.25 ounces (1 ounce = 28.3 g). What is the wavelength of a 5.15-ounce base ball thrown at 92 mph?

Jenna Ortiguerra 4G

The T in the problems stands for metric tons.
1t=1000kg
1kg=1000g
Therefore, 1t= 1,000,000g.

Jenna Ortiguerra 4G

Yes, mmol (or milimole) does mean 10^-3 moles, or you can just move the decimal to the left by three to convert from moles to millimoles. When converting from moles to grams, you need to find the molar mass of the compound which will be in g*mol^-1. Using that, you would use mol/g*mol^-1 (moles woul...

Jenna Ortiguerra 4G

M1= initial molarity V1= initial volume M2= final molarity V2= final volume M1V1=M2V2 is used to solve for the concentration or volume of the concentrated or dilute solution. Thus, you can use the formula M1V1=M2V2 when you are trying to solve from the initial molarity, initial volume, final molarit...

Jenna Ortiguerra 4G

In a and b, convert the following given grams to moles by using the element's molar mass. In c, convert the following given atoms to moles by using Avogadro's number (6.022*10^23) a. 75g/114.82 g*mol^-1 = 0.65 mol In 80g/127.60 g*mol^-1 = 0.63 mol Te 0.65 mol In > 0.63 mol Te b. 15.0g/30.97 g*mol^-1...

Jenna Ortiguerra 4G

Avogadro's constant is 6.0221 x 10^23 mol^-1. Avogadro's number is typically used to convert between number of moles and the # of atoms, ions, or molecules!

Jenna Ortiguerra 4G

You need the illustration to answer the problem, and it will also help you conceptualize it! According to the question, the molar mass of astatine is triple to amount of gallium. The illustration shows 9 astatine and 9 gallium atoms. For Gallium, 9 x 70 g/mol = 630 g/mol. Therefore, to find how many...

Jenna Ortiguerra 4G

The question is asking you to calculate the amount of carbon ATOMS in the molecule of DNA. To convert atoms into moles, you use Avogadro's number (6.022*10^23).

(2.1*10^9 atoms) * ((1molC)/(6.022*10^23 C)) = 3.5*10^-15 moles C

The amount of moles in carbon is 3.5 * 10^-15 moles C

Jenna Ortiguerra 4G

I also answered the same question here https://lavelle.chem.ucla.edu/forum/viewtopic.php?f=26&t=46183 ! First, you want to find the molar mass of (OH)2. O=2(15.9994)=31.9988 H=2(1.00795)= 2.01588 31.9988+2.01588= 34.01468, which is about 34.02 g*mol^-1 (this is what is used in the solution manua...

Jenna Ortiguerra 4G

1) First, you would have to calculate the molar mass of the (OH)2. O=2(15.9994)=31.9988 H=2(1.00795)= 2.01588 31.9988+2.01588= 34.01468, which is ~34.02 (seen in the solution manual). 2) Subtract the given molar mass of the metal hydroxide and the molar mass we calculated above. 74.10 g*mol^-1 - 34....

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