Search found 51 matches

by RoshniVarmaDis1K
Thu Dec 05, 2019 1:23 am
Forum: Naming
Topic: Roman numerals
Replies: 7
Views: 64

Re: Roman numerals

The roman numeral is equal to the charge on the transition metal.
by RoshniVarmaDis1K
Thu Dec 05, 2019 1:20 am
Forum: Naming
Topic: Ligands
Replies: 2
Views: 28

Re: Ligands

There is also a list of common ligands on the class website.
by RoshniVarmaDis1K
Thu Dec 05, 2019 1:18 am
Forum: Lewis Acids & Bases
Topic: Salts as Acids and Bases
Replies: 2
Views: 23

Re: Salts as Acids and Bases

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.
by RoshniVarmaDis1K
Thu Dec 05, 2019 1:16 am
Forum: Properties & Structures of Inorganic & Organic Acids
Topic: How does anion stability contribute to relative acidity?
Replies: 6
Views: 57

Re: How does anion stability contribute to relative acidity?

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.
by RoshniVarmaDis1K
Thu Dec 05, 2019 12:56 am
Forum: Bronsted Acids & Bases
Topic: HF is a weak acid?
Replies: 8
Views: 71

Re: HF is a weak acid?

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.
by RoshniVarmaDis1K
Fri Nov 29, 2019 4:11 pm
Forum: Calculating the pH of Salt Solutions
Topic: pH vs. pOH
Replies: 17
Views: 171

Re: pH vs. pOH

pH measures the concentration of H3O+ ions while pOH measure the concentration of OH- ions.
by RoshniVarmaDis1K
Fri Nov 29, 2019 4:09 pm
Forum: Calculating pH or pOH for Strong & Weak Acids & Bases
Topic: Strength and Weakness
Replies: 12
Views: 348

Re: Strength and Weakness

An acid that dissociates more easily (longer bond length) is a stronger acid and will have a higher KA value.
by RoshniVarmaDis1K
Fri Nov 29, 2019 4:07 pm
Forum: Lewis Acids & Bases
Topic: Proton acceptor and proton donor?
Replies: 33
Views: 186

Re: Proton acceptor and proton donor?

Acids are proton donors and bases are proton acceptors.
by RoshniVarmaDis1K
Fri Nov 29, 2019 4:06 pm
Forum: Lewis Acids & Bases
Topic: HCl vs HF
Replies: 19
Views: 118

Re: HCl vs HF

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.
by RoshniVarmaDis1K
Fri Nov 29, 2019 4:04 pm
Forum: Hybridization
Topic: Sigma and Pi bonds
Replies: 7
Views: 65

Re: Sigma and Pi bonds

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.
by RoshniVarmaDis1K
Mon Nov 18, 2019 3:41 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Formal Charge
Replies: 2
Views: 16

Re: Formal Charge

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.
by RoshniVarmaDis1K
Mon Nov 18, 2019 3:39 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Polar VSEPR's
Replies: 1
Views: 14

Re: Polar VSEPR's

Yes, all O atoms have the same electronegativity. CO2 is considered nonpolar.
by RoshniVarmaDis1K
Mon Nov 18, 2019 3:35 pm
Forum: Dipole Moments
Topic: Effects for boiling point
Replies: 5
Views: 36

Re: Effects for boiling point

A molecule with stronger IMFs will have a higher boiling point because more heat energy is required to overcome the interactions.
by RoshniVarmaDis1K
Mon Nov 18, 2019 3:31 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: 2 VSEPR's
Replies: 2
Views: 16

Re: 2 VSEPR's

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.
by RoshniVarmaDis1K
Mon Nov 18, 2019 3:29 pm
Forum: Interionic and Intermolecular Forces (Ion-Ion, Ion-Dipole, Dipole-Dipole, Dipole-Induced Dipole, Dispersion/Induced Dipole-Induced Dipole/London Forces, Hydrogen Bonding)
Topic: IM Forces
Replies: 3
Views: 27

Re: IM Forces

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.
by RoshniVarmaDis1K
Wed Nov 13, 2019 8:57 pm
Forum: Ionic & Covalent Bonds
Topic: 2D #11
Replies: 3
Views: 30

Re: 2D #11

Cations have polarizing power because they can pull electrons.

Anions are polarizable because they have the electrons that are pulled away.
by RoshniVarmaDis1K
Wed Nov 13, 2019 8:56 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Will we need to know these VSEPR shapes as well?
Replies: 10
Views: 90

Re: Will we need to know these VSEPR shapes as well?

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.
by RoshniVarmaDis1K
Wed Nov 13, 2019 8:55 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: VSEPR model angles
Replies: 7
Views: 47

Re: VSEPR model angles

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.
by RoshniVarmaDis1K
Wed Nov 13, 2019 8:51 pm
Forum: Ionic & Covalent Bonds
Topic: HW 2D #5
Replies: 2
Views: 27

Re: HW 2D #5

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.
by RoshniVarmaDis1K
Wed Nov 13, 2019 12:10 pm
Forum: Octet Exceptions
Topic: Incomplete Octets
Replies: 4
Views: 89

Re: Incomplete Octets

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...
by RoshniVarmaDis1K
Mon Nov 04, 2019 2:29 pm
Forum: Polarisability of Anions, The Polarizing Power of Cations
Topic: Distorted e- as highly polarizable
Replies: 5
Views: 62

Re: Distorted e- as highly polarizable

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 ...
by RoshniVarmaDis1K
Mon Nov 04, 2019 2:25 pm
Forum: Lewis Structures
Topic: Lewis Structures
Replies: 3
Views: 27

Re: Lewis Structures

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.
by RoshniVarmaDis1K
Mon Nov 04, 2019 1:31 pm
Forum: Octet Exceptions
Topic: Identifying Radicals
Replies: 6
Views: 60

Re: Identifying Radicals

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.
by RoshniVarmaDis1K
Mon Nov 04, 2019 1:28 pm
Forum: Formal Charge and Oxidation Numbers
Topic: Formal Charge/Lewis structures
Replies: 5
Views: 40

Re: Formal Charge/Lewis structures

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.
by RoshniVarmaDis1K
Mon Nov 04, 2019 1:27 pm
Forum: Ionic & Covalent Bonds
Topic: Covalent and Ionic Bonds
Replies: 6
Views: 50

Re: Covalent and Ionic Bonds

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 ...
by RoshniVarmaDis1K
Sun Oct 27, 2019 5:50 pm
Forum: Trends in The Periodic Table
Topic: 1F.19
Replies: 2
Views: 23

Re: 1F.19

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.
by RoshniVarmaDis1K
Sun Oct 27, 2019 5:44 pm
Forum: Lewis Structures
Topic: expanded-octet
Replies: 4
Views: 33

Re: expanded-octet

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.
by RoshniVarmaDis1K
Sun Oct 27, 2019 5:38 pm
Forum: Ionic & Covalent Bonds
Topic: 2A.24
Replies: 3
Views: 28

Re: 2A.24

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.
by RoshniVarmaDis1K
Sun Oct 27, 2019 5:35 pm
Forum: Octet Exceptions
Topic: Exceeding the Octet Rule
Replies: 5
Views: 75

Re: Exceeding the Octet Rule

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.
by RoshniVarmaDis1K
Sun Oct 27, 2019 5:27 pm
Forum: Resonance Structures
Topic: Pointers For Appropriate Resonance Structures
Replies: 2
Views: 30

Re: Pointers For Appropriate Resonance Structures

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.
by RoshniVarmaDis1K
Wed Oct 23, 2019 3:27 pm
Forum: Electron Configurations for Multi-Electron Atoms
Topic: Electron Spin
Replies: 8
Views: 63

Re: Electron Spin

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.
by RoshniVarmaDis1K
Wed Oct 23, 2019 3:24 pm
Forum: Trends in The Periodic Table
Topic: Ionization Energy
Replies: 8
Views: 79

Re: Ionization Energy

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.
by RoshniVarmaDis1K
Wed Oct 23, 2019 3:21 pm
Forum: Trends in The Periodic Table
Topic: 2nd Ionization Energy
Replies: 7
Views: 50

Re: 2nd Ionization Energy

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.
by RoshniVarmaDis1K
Wed Oct 23, 2019 3:20 pm
Forum: Trends in The Periodic Table
Topic: Ionization Energy for the 2nd Electron
Replies: 3
Views: 22

Re: Ionization Energy for the 2nd Electron

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...
by RoshniVarmaDis1K
Mon Oct 21, 2019 5:13 pm
Forum: Wave Functions and s-, p-, d-, f- Orbitals
Topic: Quantum Numbers
Replies: 7
Views: 98

Re: Quantum Numbers

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 ...
by RoshniVarmaDis1K
Mon Oct 21, 2019 4:20 pm
Forum: Trends in The Periodic Table
Topic: Focus 1 Exercise 1.13
Replies: 3
Views: 30

Re: Focus 1 Exercise 1.13

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-...
by RoshniVarmaDis1K
Wed Oct 16, 2019 2:34 pm
Forum: Wave Functions and s-, p-, d-, f- Orbitals
Topic: 1.D.23 [ENDORSED]
Replies: 2
Views: 56

Re: 1.D.23 [ENDORSED]

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...
by RoshniVarmaDis1K
Wed Oct 16, 2019 2:28 pm
Forum: Wave Functions and s-, p-, d-, f- Orbitals
Topic: What are subshells
Replies: 4
Views: 52

Re: What are subshells

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 (px, py, and pz) orbitals.
by RoshniVarmaDis1K
Wed Oct 16, 2019 2:23 pm
Forum: Wave Functions and s-, p-, d-, f- Orbitals
Topic: Quantum Numbers
Replies: 7
Views: 98

Re: Quantum Numbers

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...
by RoshniVarmaDis1K
Wed Oct 16, 2019 2:13 pm
Forum: Quantum Numbers and The H-Atom
Topic: 1.D Quantum Numbers
Replies: 2
Views: 46

Re: 1.D Quantum Numbers

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...
by RoshniVarmaDis1K
Wed Oct 16, 2019 2:10 pm
Forum: Quantum Numbers and The H-Atom
Topic: 1D 11
Replies: 4
Views: 49

Re: 1D 11

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 ...
by RoshniVarmaDis1K
Wed Oct 09, 2019 4:24 pm
Forum: Bohr Frequency Condition, H-Atom , Atomic Spectroscopy
Topic: Photon Absorption/Emission
Replies: 8
Views: 125

Re: Photon Absorption/Emission

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.
by RoshniVarmaDis1K
Wed Oct 09, 2019 4:22 pm
Forum: Bohr Frequency Condition, H-Atom , Atomic Spectroscopy
Topic: Spectral Lines
Replies: 3
Views: 68

Re: Spectral Lines

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>...
by RoshniVarmaDis1K
Wed Oct 09, 2019 4:19 pm
Forum: Bohr Frequency Condition, H-Atom , Atomic Spectroscopy
Topic: Calculating Energy per Photon
Replies: 3
Views: 32

Re: Calculating Energy per Photon

E = hv
E = (6.626*10-34 J*s) x (3.00*1015 Hz)
E = 1.99*10-18 J
by RoshniVarmaDis1K
Wed Oct 09, 2019 4:16 pm
Forum: Photoelectric Effect
Topic: Photon [ENDORSED]
Replies: 6
Views: 99

Re: Photon [ENDORSED]

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.
by RoshniVarmaDis1K
Wed Oct 09, 2019 4:06 pm
Forum: Properties of Light
Topic: Kinetic Energy
Replies: 2
Views: 55

Re: Kinetic Energy

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...
by RoshniVarmaDis1K
Mon Sep 30, 2019 8:56 pm
Forum: Empirical & Molecular Formulas
Topic: Percent Mass Composition
Replies: 7
Views: 167

Re: Percent Mass Composition

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...
by RoshniVarmaDis1K
Mon Sep 30, 2019 8:52 pm
Forum: Balancing Chemical Reactions
Topic: Balancing Reactions
Replies: 25
Views: 343

Re: Balancing Reactions

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...
by RoshniVarmaDis1K
Mon Sep 30, 2019 8:49 pm
Forum: Molarity, Solutions, Dilutions
Topic: HW Fundamentals E15- what is 34.02 grams?
Replies: 3
Views: 61

Re: HW Fundamentals E15- what is 34.02 grams?

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.
by RoshniVarmaDis1K
Mon Sep 30, 2019 8:46 pm
Forum: Significant Figures
Topic: Calculations With Significant Figures
Replies: 3
Views: 92

Re: Calculations With Significant Figures

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...
by RoshniVarmaDis1K
Mon Sep 30, 2019 8:40 pm
Forum: Empirical & Molecular Formulas
Topic: Fundamentals L.39:
Replies: 3
Views: 139

Re: Fundamentals L.39:

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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