CHEMISTRY COMMUNITY

Junyong Wu

The first bond to be broken is the pi bond.

Junyong Wu

Yes, single bond is the longest and weakest bond, so it requires less energy to break apart.

Junyong Wu

I guess with a small radius, electron pulling power will increase, so electronegativity increases.

Junyong Wu

I guess formal charge is calculated by the formula V-L-S/2 and the oxidation number is the number of e- gain or lose to fulfill the octet or duplet.

Junyong Wu

h equal 6.626*10^(-34) J/s

Junyong Wu

A greater difference of in electronegativity will increase the ionic character, so it will be more soluble.

Junyong Wu

Because strong acid are completely ionized in water.

Junyong Wu

Al3+ and Cu2+ react with OH-, Cl- and (NO3)-will not affect pH.

Junyong Wu

delta velocity would be 1.2

Junyong Wu

Noble gases are stable, unreactive, they are neither acid nor base.

Junyong Wu

In the example CCl3COOH vs. CH3COOH, Cl has higher electronegativity, so the CCl3COO- will be more stable, and there will be more H+, making CCl3COOH a strong acid than CH3COOH.

Junyong Wu

I think we need use the formula to calculate the pH, but we cannot get the exact pH from the structure.

Junyong Wu

Yes, metals usually lose electrons to form cations, and non-metals will gain electrons to form anions.

Junyong Wu

Such as BeO, Al2O3, Ga2O3, SnO2, Sb2O3, PbO2

Junyong Wu

I guess it is because the formal charge of two oxygens are -1, therefore, CO3 2- can donate either 1 e- pair or 2 e- pairs

Junyong Wu

because edta is hexadentae, it can donate 6 e- pairs

Junyong Wu

we use these to indicate the number of type of ligand, and when the ligand already contains a Greek prefix or if it is polydentate, then use bis-, tris-, tetrakis

Junyong Wu

Because F has stronger electronegativity than Cl.

Junyong Wu

Lewis acids are e-pair acceptors and proton donors, and Lewis bases are e- pair donors and proton acceptors.

Junyong Wu

I believe most biological compound with nitrogen lone pair are weak bases.

Junyong Wu

Yes, they are.

Junyong Wu

The PR means pair, and ligands are electron pair donors.

Junyong Wu

The formal charge for N: 5-2-6/2=0, therefore, it is neutral.

Junyong Wu

The Lewis bases attached to the central metal atom or ion in a d-metal complex are known as ligands, they must have one or more lone pairs and are e- pair donor, such as -NH3

Junyong Wu

The formal charge for H should be zero, 1-0-2/2=0

Junyong Wu

Only p block atoms in period 3 or later periods can expand their valence shells.

Junyong Wu

Atom with higher ionization energy will be harder to lose electron therefore it is harder to have positive charge, it that right?

Junyong Wu

Can someone explain what is coordinate covalent bond and give some examples?

Junyong Wu

Ionization energy is the minimum energy needed to remove an electron from an atom in the gas phase. It increases across a period and decrease down a group. And 2nd electron is required more energy to be removed for the same atom. The atom with lower ionization energy will be the center atom of a mol...

Junyong Wu

The formal charge can help to figure out the most stable lewis structure.

Junyong Wu

The molecule is delocalized therefore the bond length is somewhere between the length of single bond and double bond.

Junyong Wu

Because it is easier for them to lose valence e-.

Junyong Wu

I believe it is the procedure we followed to write the ground-state electron configuration, which can be summarized by Pauli exclusion principle and Hund's rule.

Junyong Wu

The 4s has lower energy than 3d, it needs to be filled first, but after it is filled, it has higher energy than 3d, then 3d is written before 4s. And 4s will lose electron first.

Junyong Wu

You should choose all of them.

Junyong Wu

I think it is because they don't have 8 valence electrons after forming chemical bonds.

Junyong Wu

It requires extremely high energy for noble gas to form a molecule or compound. And none of them is diatomic.

Junyong Wu

ml=l,l-1,...,-l, it represents the orbital in a subshell

Junyong Wu

(c) Electrons having l=2 are better at shielding than electrons having l=1. Can someone explain why this wrong?

Junyong Wu

So it will fill 4s first and then 3d except chromium and copper?

Junyong Wu

In p-orbital, ml=+1 indicates px or pz?

Junyong Wu

Why n=3, l=2,m=+/-1 has only one orbital?

Junyong Wu

The E,coli bacterium is about 2.2 μm long. Suppose you want to study it using photons of that wavelength or electrons having that de Broglie wavelength.
What is the energy of the photon? What is the energy of the electron?

How to solve for the energy of the electron for this problem?

Junyong Wu

First, the ultraviolet spectrum gives you n1=1, then you can find E(final) = -hR/n1^2.
Then, delta E = hc/λ, since it emits energy, it is from high level to low level, delta should be negative.
then, E(initial)= E(final)-delta E, and solve for n2 from E(initial) = -hR/n2^2

Junyong Wu

Yes, the amplitude represents the height of the wave.

Junyong Wu

For E=hv, is it calculating the energy for one photon?

Junyong Wu

I believe so, because we need to know it to calculate kinetic energy and sometimes for calculating the wavelength.

Junyong Wu

Yes. because electron and photon have wave-like properties.

Junyong Wu

An electron requires to absorb energy in order to go to a higher level, therefore delta E should be positive.

Junyong Wu

From the following list of observations, select the one that best supports the idea that electromagnetic radiation has the properties of particles. Explain your reasoning. (a) Black-body radiation. (b) Electron diffraction. (c) Atomic spectra. (d) The photoelectric effect. I was confused between c a...

Junyong Wu

For this question, I think we first need to solve for the limiting reactant in the 1st equation. If P4 is the limiting reactant, solve for the mass of oxygen left.
Then, we could use that mass to find the limiting reactant in the 2nd equation.

Junyong Wu

1. balance the equation
2. solve for molar mass of each reactant and product
3. convert molar mass to moles
4. the smallest will be the limiting reactant

Junyong Wu

I think reading the textbook can be a way for us to review and doing more practice could help a lot.

Junyong Wu

It is much more interesting to learn chemistry by combining it with cooking and baking!!

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