Search found 50 matches

by Heba Mengesha 3D
Sun Dec 08, 2019 9:11 pm
Forum: Shape, Structure, Coordination Number, Ligands
Topic: Chelates
Replies: 3
Views: 37

Re: Chelates

Yes, all polydentate ligands are chelating agents.
by Heba Mengesha 3D
Sun Dec 08, 2019 9:10 pm
Forum: Quantum Numbers and The H-Atom
Topic: The spin of a quantum number
Replies: 6
Views: 45

Re: The spin of a quantum number

I believe because electrons of the same spin cancel each other out, the one unpaired electron in the atom will determine the spin.
by Heba Mengesha 3D
Sun Dec 08, 2019 9:07 pm
Forum: Lewis Acids & Bases
Topic: What does it mean when something is strong?
Replies: 8
Views: 54

Re: What does it mean when something is strong?

Acids and bases that are completely ionized when dissolved in water are called strong acids and bases.
by Heba Mengesha 3D
Sun Dec 08, 2019 8:53 pm
Forum: Resonance Structures
Topic: Best Resonance Structure
Replies: 5
Views: 55

Re: Best Resonance Structure

Since the formal charge can be negative or positive, the lower the formal charge, the higher the stability.
by Heba Mengesha 3D
Sun Dec 08, 2019 8:50 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: boiling point
Replies: 8
Views: 41

Re: boiling point

The boiling point of a molecule depends on its structure. It can depend on the intermolecular forces present between the atoms or molecules and boiling points increase as the size of the molecule increases.
by Heba Mengesha 3D
Sun Dec 01, 2019 5:37 pm
Forum: Lewis Acids & Bases
Topic: bronsted vs lewis
Replies: 9
Views: 43

Re: bronsted vs lewis

A Bronsted base is a proton acceptor, while a Lewis acid is an electron acceptor. One way to tell the difference is to count the number of hydrogen ions. If the number of hydrogens has decreased that substance is the acid (donates hydrogen ions). If the number of hydrogens has increased that substan...
by Heba Mengesha 3D
Sun Dec 01, 2019 5:33 pm
Forum: Amphoteric Compounds
Topic: Identifying Them?
Replies: 12
Views: 62

Re: Identifying Them?

An amphoteric substance is one which can both donate hydrogen ions (protons) and also accept them.
by Heba Mengesha 3D
Sun Dec 01, 2019 5:30 pm
Forum: Bronsted Acids & Bases
Topic: naming
Replies: 4
Views: 36

Re: naming

Acids are named based on their anion; the ion attached to the hydrogen. Most strong bases contain hydroxide, a polyatomic ion for example: NaOH is sodium hydroxide and KOH is potassium hydroxide.
by Heba Mengesha 3D
Sun Dec 01, 2019 5:24 pm
Forum: Lewis Acids & Bases
Topic: strong and weak acids
Replies: 3
Views: 21

Re: strong and weak acids

Some strong acids include: Hydrochloric acid, Nitric Acid, and sulfuric acids. And some weak acids include: Carbonic Acid, and Vinegar. A strong base is a base that is 100% ionized in solution. If it is less than 100% ionized in solution, it is a weak base.
by Heba Mengesha 3D
Sun Dec 01, 2019 5:20 pm
Forum: Calculating pH or pOH for Strong & Weak Acids & Bases
Topic: pH scale
Replies: 12
Views: 59

Re: pH scale

I believe that the pH scale is not limited to 0-14, but most common solutions fall into this range.
by Heba Mengesha 3D
Sun Nov 24, 2019 5:52 pm
Forum: Shape, Structure, Coordination Number, Ligands
Topic: Molecular shape vs Electron Configuration
Replies: 4
Views: 22

Re: Molecular shape vs Electron Configuration

Electron geometry describes the arrangement of electron groups. Molecular geometry describes the arrangement of atoms, excluding lone pairs.
by Heba Mengesha 3D
Wed Nov 20, 2019 9:24 am
Forum: Determining Molecular Shape (VSEPR)
Topic: N2O Lewis Structure/Pi and Sigma Bonds
Replies: 2
Views: 21

Re: N2O Lewis Structure/Pi and Sigma Bonds

The central atom is determined by knowing the least electronegative atom which in this case would be Nitrogen. N2O has 2 pi bonds and 2 sigma bonds.
by Heba Mengesha 3D
Wed Nov 20, 2019 9:21 am
Forum: Dipole Moments
Topic: melting point
Replies: 1
Views: 46

Re: melting point

When considering melting points a larger atom with more electrons → higher polarizability → stronger intermolecular force → higher boiling/melting point. Therefore, CHI3 is a larger atom compared to CHF3.
by Heba Mengesha 3D
Wed Nov 20, 2019 9:16 am
Forum: Determining Molecular Shape (VSEPR)
Topic: Polarity Diatomic Molecules
Replies: 1
Views: 15

Re: Polarity Diatomic Molecules

If a diatomic molecule consists of two atoms of the same element, the molecule has to be non polar like H-H or O-O
by Heba Mengesha 3D
Wed Nov 20, 2019 9:12 am
Forum: Determining Molecular Shape (VSEPR)
Topic: Resonance and Rotation
Replies: 1
Views: 20

Re: Resonance and Rotation

Resonance structures involve the movement of pi-bonded electrons or of lone-pair electrons that are adjacent to pi bonds. You can't shift the location of electrons in sigma bonds – if you show a sigma bond forming or breaking, you are showing a chemical reaction taking place. The positions of atoms ...
by Heba Mengesha 3D
Tue Nov 19, 2019 1:20 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Bond Angles
Replies: 4
Views: 32

Re: Bond Angles

You would know when a bond angle is "slightly less than" because of the existence of the lone pairs surrounding the atom. The lone pairs have a stronger electron repulsion pushing the other atoms farther away. This would make the bond angle "slightly less than..."
by Heba Mengesha 3D
Tue Nov 19, 2019 1:13 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Linear Shape
Replies: 6
Views: 33

Re: Linear Shape

A linear shape may or may not be polar depending on if the molecule is symmetrical or not.
by Heba Mengesha 3D
Tue Nov 19, 2019 1:10 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: seesaw
Replies: 5
Views: 43

Re: seesaw

The repulsion of the lone pairs will cause the bond angles to be slightly less than 90 and 120 degrees.
by Heba Mengesha 3D
Tue Nov 19, 2019 1:09 pm
Forum: Bond Lengths & Energies
Topic: Boiling point
Replies: 11
Views: 77

Re: Boiling point

For molecules, the boiling point increases with molecular weight.
by Heba Mengesha 3D
Mon Nov 04, 2019 8:50 pm
Forum: Lewis Structures
Topic: Lewis Structure
Replies: 4
Views: 33

Re: Lewis Structure

Usually the central atom will be the one that has the most unpaired valence electrons. The central atom is also usually the least electronegative.
by Heba Mengesha 3D
Mon Nov 04, 2019 8:48 pm
Forum: Electron Configurations for Multi-Electron Atoms
Topic: Atoms after f-block
Replies: 2
Views: 31

Re: Atoms after f-block

I believe we do not need to know anything in the f-block for our midterm
by Heba Mengesha 3D
Mon Nov 04, 2019 8:45 pm
Forum: Ionic & Covalent Bonds
Topic: Bond Lengths
Replies: 4
Views: 38

Re: Bond Lengths

You will most likely be given a table on bond lengths if we need it
by Heba Mengesha 3D
Mon Nov 04, 2019 8:43 pm
Forum: Wave Functions and s-, p-, d-, f- Orbitals
Topic: Atomic Orbitals
Replies: 2
Views: 45

Re: Atomic Orbitals

The chance of finding an electron in that region
by Heba Mengesha 3D
Mon Nov 04, 2019 8:41 pm
Forum: Molarity, Solutions, Dilutions
Topic: Textbook question
Replies: 3
Views: 85

Re: Textbook question

m is for the mass of the element and M is from molarity
by Heba Mengesha 3D
Mon Nov 04, 2019 8:35 pm
Forum: Resonance Structures
Topic: Formal charge and resonance
Replies: 5
Views: 57

Re: Formal charge and resonance

Yes resonance structures can have different formal charges because you move the electrons and bonds around the atom resulting in different charges.
by Heba Mengesha 3D
Mon Nov 04, 2019 8:20 pm
Forum: Student Social/Study Group
Topic: Final
Replies: 11
Views: 97

Re: Final

Yes our final is on Sunday December 8.
by Heba Mengesha 3D
Mon Nov 04, 2019 8:15 pm
Forum: Polarisability of Anions, The Polarizing Power of Cations
Topic: Polarisability vs Polarizing Power
Replies: 15
Views: 111

Re: Polarisability vs Polarizing Power

Smaller, more positive cations would pull electrons more strongly, so they have more polarizing power. On the other hand, polarizability is the ability to pull those electrons towards the anion.
by Heba Mengesha 3D
Mon Nov 04, 2019 9:45 am
Forum: Bond Lengths & Energies
Topic: Factors
Replies: 1
Views: 22

Re: Factors

In ionic bonds, charge and distance are the two factors that affect the strength of the bond. The more electrons transferred, the stronger the bond. The difference from the nucleus is also a factor. The closer the nuclei to the electrons of the other atom, the less energy levels of electrons that ar...
by Heba Mengesha 3D
Mon Nov 04, 2019 9:41 am
Forum: Electronegativity
Topic: Difference
Replies: 5
Views: 29

Re: Difference

Electronegativity is an atom's ability to attract electrons, as in a covalent bond. Polarizability increases with decreasing element binding energy
by Heba Mengesha 3D
Sun Oct 27, 2019 9:53 pm
Forum: Ionic & Covalent Bonds
Topic: Covalent Bonds
Replies: 14
Views: 96

Re: Covalent Bonds

covalent bonds form when electrons are shared between two nonmetals. Nonmetals can however form different types of bonds depending on their partner atoms.
by Heba Mengesha 3D
Sun Oct 27, 2019 9:51 pm
Forum: Administrative Questions and Class Announcements
Topic: Study Tips!
Replies: 7
Views: 50

Re: Study Tips!

The workshops and step up sessions are really helpful. Also I would watch the audio visuals for each topic and review your lecture notes.
by Heba Mengesha 3D
Sun Oct 27, 2019 9:48 pm
Forum: Ionic & Covalent Bonds
Topic: Single bond vs. Double bond vs. Triple bond
Replies: 3
Views: 40

Re: Single bond vs. Double bond vs. Triple bond

Single bonds have fewer negatively charged electrons shared between two atoms than double or triple bonds, so they don't attract the positively charged nuclei of the atoms as strongly as bonds with more electrons.
by Heba Mengesha 3D
Sun Oct 27, 2019 9:47 pm
Forum: Formal Charge and Oxidation Numbers
Topic: Formal charge
Replies: 3
Views: 32

Re: Formal charge

Yes, use the formal charge equation to find the charge of each atom.
by Heba Mengesha 3D
Sun Oct 27, 2019 9:34 pm
Forum: Student Social/Study Group
Topic: Midterm Length
Replies: 7
Views: 91

Re: Midterm Length

When you go on the Lavelle's website it states that the midterm location will be posted at a later date. Maybe this week we'll find out.
by Heba Mengesha 3D
Sun Oct 27, 2019 9:31 pm
Forum: Ionic & Covalent Bonds
Topic: Ionic VS. Covalent Bond
Replies: 8
Views: 36

Re: Ionic VS. Covalent Bond

Covalent bonds are formed between two non-metals, whereas ionic bonds are formed between a metal and non-metal.
by Heba Mengesha 3D
Sun Oct 27, 2019 9:24 pm
Forum: Dipole Moments
Topic: Dipole Moments
Replies: 2
Views: 30

Re: Dipole Moments

Dipole moments occur when there is a separation of charge and arise from differences in electronegativity. The larger the difference in electronegativity, the larger the dipole moment.
by Heba Mengesha 3D
Tue Oct 22, 2019 7:56 pm
Forum: General Science Questions
Topic: Study Tips
Replies: 13
Views: 130

Re: Study Tips

Definitely do as MANY homework problems as you can. They help solidify the material we learn in lecture!
by Heba Mengesha 3D
Tue Oct 22, 2019 7:54 pm
Forum: Properties of Electrons
Topic: d-orbital in the electron configuration
Replies: 3
Views: 30

Re: d-orbital in the electron configuration

s-orbital electrons are closer to the nucleus (more stable) and farther from the nucleus (less stable) compared to the corresponding d-orbitals. This makes them favorable to occupy when no d-electrons are present, but less favorable to occupy when d-electrons are present, which is why they are fille...
by Heba Mengesha 3D
Tue Oct 22, 2019 4:25 pm
Forum: Properties of Electrons
Topic: x,y,z for Electrons
Replies: 10
Views: 78

Re: x,y,z for Electrons

X,Y,Z is just a label for each of the three orbital subsets.
by Heba Mengesha 3D
Mon Oct 14, 2019 10:03 pm
Forum: Bohr Frequency Condition, H-Atom , Atomic Spectroscopy
Topic: Best Way To Study?
Replies: 56
Views: 390

Re: Best Way To Study?

Watching the learning modules along with Youtube videos which help me better understand how to apply the concepts discussed in Lectures. Also do plenty of practice problems from the textbook!
by Heba Mengesha 3D
Mon Oct 14, 2019 9:22 pm
Forum: Einstein Equation
Topic: E=hv
Replies: 43
Views: 2236

Re: E=hv

E represents the energy (in joules) of the particle of light.
by Heba Mengesha 3D
Mon Oct 14, 2019 9:04 pm
Forum: *Shrodinger Equation
Topic: probability vs probability density
Replies: 3
Views: 53

Re: probability vs probability density

Probability density is a "density" function. While probability is a specific value. The probability density function for a given value of X represents the density of probability.
by Heba Mengesha 3D
Mon Oct 14, 2019 8:39 pm
Forum: DeBroglie Equation
Topic: Neutron Diffraction
Replies: 1
Views: 14

Re: Neutron Diffraction

Yes neutrons will create diffraction patterns if passed through a crystal because they have wave-like properties like electrons.
by Heba Mengesha 3D
Mon Oct 14, 2019 8:30 pm
Forum: Heisenberg Indeterminacy (Uncertainty) Equation
Topic: Heisenberg indeterminacy equation
Replies: 2
Views: 27

Re: Heisenberg indeterminacy equation

ΔpΔx≥h/4π is equal to ΔpΔx≥h/2
by Heba Mengesha 3D
Mon Oct 07, 2019 12:30 am
Forum: Limiting Reactant Calculations
Topic: Question about Calculating Limiting Reactants
Replies: 5
Views: 48

Re: Question about Calculating Limiting Reactants

Yes. One method is to find and compare the mole ratio of the reactants used in the reaction to find the limiting reactant (reagent).
by Heba Mengesha 3D
Mon Oct 07, 2019 12:16 am
Forum: SI Units, Unit Conversions
Topic: Are there going to be any questions on this week's test regarding Quanta and Photons?
Replies: 5
Views: 75

Re: Are there going to be any questions on this week's test regarding Quanta and Photons?

Test 1 only consists of review of High School Chemistry: Review of Chemical and Physical Principles.
by Heba Mengesha 3D
Mon Oct 07, 2019 12:13 am
Forum: Significant Figures
Topic: Final Answer
Replies: 4
Views: 68

Re: Final Answer

In chemistry you should leave in powers of 10 for efficiency.
by Heba Mengesha 3D
Mon Oct 07, 2019 12:11 am
Forum: SI Units, Unit Conversions
Topic: Molar Ratio
Replies: 4
Views: 47

Re: Molar Ratio

A molar ratio is used to identify the number of moles a product that are produced from a reactant as well as to figure out how many moles are required to react with the product.
by Heba Mengesha 3D
Sun Oct 06, 2019 9:48 pm
Forum: Molarity, Solutions, Dilutions
Topic: Periodic table
Replies: 3
Views: 60

Re: Periodic table

Yes we will be provided with a periodic table along with all constants and equations.

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