Search found 48 matches

by David Zhang 1B
Tue Jul 30, 2019 9:52 pm
Forum: Identifying Acidic & Basic Salts
Topic: FeCl3 in water
Replies: 1
Views: 120

FeCl3 in water

Why doesn't the Cl- react with water in a reaction involving FeCl3 and water?
by David Zhang 1B
Mon Jul 29, 2019 11:50 pm
Forum: Lewis Acids & Bases
Topic: Spectator Ions
Replies: 1
Views: 76

Spectator Ions

How can we tell which part of an acid/base molecule is a spectator ion and doesn't react?
by David Zhang 1B
Mon Jul 29, 2019 11:05 am
Forum: Coordinate Covalent Bonds
Topic: Why can h20 only donate 1 lone pair?
Replies: 4
Views: 160

Re: Why can h20 only donate 1 lone pair?

I think the shape of the molecule also plays a role since the way the electron pairs are positioned doesn’t really allow it to form 2 bonds.
by David Zhang 1B
Wed Jul 24, 2019 11:54 pm
Forum: Bronsted Acids & Bases
Topic: Ammonia and phosphoric acid
Replies: 1
Views: 91

Ammonia and phosphoric acid

For the homework solution for Fundamentals J.9 (b), the equation written for the neutralization of ammonia and phosphoric acid doesn't include water. Do some neutralization reactions not produce water?
by David Zhang 1B
Wed Jul 24, 2019 10:24 pm
Forum: Naming
Topic: Fe------ferrate? [ENDORSED]
Replies: 8
Views: 211

Re: Fe------ferrate? [ENDORSED]

I think that's just the names that are used for naming these compounds. Cyano and cyanido are the same compound but cyano is just the older term. For iron, the Fe in the periodic table stands for ferrum, the Latin word for iron.
by David Zhang 1B
Wed Jul 24, 2019 10:21 pm
Forum: Shape, Structure, Coordination Number, Ligands
Topic: edta
Replies: 7
Views: 241

Re: edta

It can bond with a metal at 6 different sites, creating the ring structure around the atom known as a chelate.
by David Zhang 1B
Wed Jul 24, 2019 10:18 pm
Forum: *Molecular Orbital Theory Applied To Transition Metals
Topic: final exam
Replies: 5
Views: 122

Re: final exam

We will probably have to memorize them for the final. I think we only get the constants/equation sheet and the periodic table for all tests.
by David Zhang 1B
Tue Jul 23, 2019 10:56 pm
Forum: Ionic & Covalent Bonds
Topic: Xenon -- why is it the only noble gas that can form bonds?
Replies: 2
Views: 81

Re: Xenon -- why is it the only noble gas that can form bonds?

I think it's because the large radius of the atom negates part of the hold that the nucleus has on the valence electrons. When combined with a very electronegative atom, it can form bonds.
by David Zhang 1B
Tue Jul 23, 2019 10:55 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Formula from Name
Replies: 4
Views: 90

Re: Formula from Name

Yes, we will most likely be tested on that during the final. It's also a part of the homework questions so it would be good to know how to do it.
by David Zhang 1B
Mon Jul 22, 2019 10:05 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Why is AX3E2 linear?
Replies: 8
Views: 151

Re: Why is AX3E2 linear?

AX3E2 is more a T-shaped molecule with the bound atoms in a side-ways T-shape. Imagine the trigonal bipyramidal structure of AX5 but remove two of the bound atoms of the trigonal part of the molecule.
by David Zhang 1B
Mon Jul 22, 2019 10:01 pm
Forum: Octet Exceptions
Topic: Lewis Acids and Bases
Replies: 10
Views: 268

Re: Lewis Acids and Bases

Lewis acids are the molecule that has the ability to accept an entire electron pair rather than sharing the electrons. The Lewis base is the donor of the electrons.
by David Zhang 1B
Mon Jul 22, 2019 10:00 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Rotations and Shape
Replies: 4
Views: 164

Re: Rotations and Shape

I don't think it really matters since the molecule will still be the same with the same bonds.
by David Zhang 1B
Sun Jul 21, 2019 3:24 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Bond Angles
Replies: 3
Views: 75

Bond Angles

Would we have to know how to predict bond angles based on the shape of a molecule on a test?
by David Zhang 1B
Sat Jul 20, 2019 8:32 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Polarity
Replies: 7
Views: 179

Re: Polarity

A bond that is polar has atoms with a difference in electronegativity, where one atom is slightly more positive and the other is slightly more negative. This causes an unequal distribution of e- as the more electronegative atom has a greater pull on the electrons.
by David Zhang 1B
Thu Jul 18, 2019 8:48 pm
Forum: Formal Charge and Oxidation Numbers
Topic: charges and roman numerals
Replies: 3
Views: 182

Re: charges and roman numerals

The numerals indicate the charge of the atom in the molecule since transition metals can often have several ionic forms. For indium, the 3 indicates In 3+.
by David Zhang 1B
Tue Jul 16, 2019 10:16 pm
Forum: Ionic & Covalent Bonds
Topic: Inter and Intra
Replies: 8
Views: 221

Re: Inter and Intra

Intermolecular forces are forces that are responsible for interactions between different individual molecules. Intramolecular forces are the forces that act within a molecule, binding together the atoms that make up a molecule.
by David Zhang 1B
Tue Jul 16, 2019 8:26 pm
Forum: Lewis Structures
Topic: Molecule Formulas
Replies: 3
Views: 179

Molecule Formulas

Will we always be given the molecular formula on tests? In the homework, we're sometimes given only the names of the molecule such as periodate ion (2C.3).
by David Zhang 1B
Tue Jul 16, 2019 7:38 pm
Forum: Formal Charge and Oxidation Numbers
Topic: Difference between charge and formal charge [ENDORSED]
Replies: 4
Views: 220

Re: Difference between charge and formal charge [ENDORSED]

Formal charge depends on the bonds and lone pairs assigned to each atom in a structure. It compares the charge in the atom, calculated by the number of bonds divided by 2 and the number of electrons in the lone pairs, to the normal number of valence electrons.
by David Zhang 1B
Mon Jul 15, 2019 10:57 pm
Forum: Resonance Structures
Topic: Test 2
Replies: 1
Views: 93

Test 2

Will we have to have questions on test 2 as complicated as 2B.13 where we have to draw out all the resonance structures for molecules like C14H10?
by David Zhang 1B
Mon Jul 15, 2019 8:30 pm
Forum: Dipole Moments
Topic: Effect of size [ENDORSED]
Replies: 7
Views: 229

Effect of size [ENDORSED]

Why does increasing the size or molar mass result in stronger attractive interactions?
by David Zhang 1B
Mon Jul 15, 2019 8:25 pm
Forum: Polarisability of Anions, The Polarizing Power of Cations
Topic: Polarizing Power [ENDORSED]
Replies: 8
Views: 267

Re: Polarizing Power [ENDORSED]

The polarizing power of a cation allows it to distort the electron field of the cation since the negative charge of the electrons is attracted to the positive charge on the cation.
by David Zhang 1B
Fri Jul 12, 2019 9:54 pm
Forum: Octet Exceptions
Topic: breaking the octet
Replies: 7
Views: 267

Re: breaking the octet

Those atoms have a d-orbital that can be filled after the s and p orbitals have been filled, allowing them to break the octet rule.
by David Zhang 1B
Fri Jul 12, 2019 9:52 pm
Forum: Formal Charge and Oxidation Numbers
Topic: Formal Charge
Replies: 4
Views: 137

Re: Formal Charge

It's the charge on each individual atom that can be calculated after drawing a Lewis structure. Each variation of the Lewis structure has different formal charges and the structure with the most neutral charge is often the best structure.
by David Zhang 1B
Thu Jul 11, 2019 9:39 pm
Forum: Ionic & Covalent Bonds
Topic: Homework 3.5
Replies: 7
Views: 202

Re: Homework 3.5

The [Xe] fills in the 5s part. Xe's electron configuration is 1s2 2s2 2p6 3s2 3p6 3d10 4s2 4p6 4d10 5s2 5p6. The 4f14 5d10 6s2 come after the 5p6 to create the full electron configuration.
by David Zhang 1B
Thu Jul 11, 2019 9:35 pm
Forum: Ionic & Covalent Bonds
Topic: Ionic Character
Replies: 4
Views: 132

Re: Ionic Character

There are tables that list out the electronegativity values that you can use to compare to determine the difference in electronegativity. However, we won't get to use one on a test so it's mostly about understanding electronegativity trends in the periodic table. Electronegativity generally increase...
by David Zhang 1B
Thu Jul 11, 2019 9:33 pm
Forum: Resonance Structures
Topic: Lewis Structures vs. Resonance
Replies: 2
Views: 101

Re: Lewis Structures vs. Resonance

Resonance is referring to the different ways that you could write out a Lewis structure since there are usually multiple valid ways you write one with differing types of bonds or lone pairs. While all the ways are valid, there are usually some structures that seem more stable.
by David Zhang 1B
Wed Jul 10, 2019 9:40 pm
Forum: Electron Configurations for Multi-Electron Atoms
Topic: 6th edition 19b [ENDORSED]
Replies: 2
Views: 130

Re: 6th edition 19b [ENDORSED]

The 4+ means that 4 electrons have been removed. A natural Sn atom would have [Kr]4d^10 5s^2 5p^2. Taking away 4 electrons from the valence would make it [Kr] 4d^10.
by David Zhang 1B
Wed Jul 10, 2019 12:03 am
Forum: Wave Functions and s-, p-, d-, f- Orbitals
Topic: Number of orbitals given quantum numbers
Replies: 3
Views: 106

Re: Number of orbitals given quantum numbers

Orbital number is determined by the equation n^2. With n=2, you have both l=0 (s subshell) and l=1 (p subshell). For l=0, the s subshell only has 1 orbital (0). For l=1, the p subshell has 3 orbitals (+1,0,-1). Combined, there are 4 orbitals total.
by David Zhang 1B
Sun Jul 07, 2019 4:21 pm
Forum: Trends in The Periodic Table
Topic: Element Names
Replies: 2
Views: 183

Element Names

For the periodic table that we use during tests, do we have to know the abbreviations for all the elements or will the names be written out for us?
by David Zhang 1B
Sat Jul 06, 2019 8:40 pm
Forum: Electron Configurations for Multi-Electron Atoms
Topic: Chromium and Copper [ENDORSED]
Replies: 1
Views: 126

Chromium and Copper [ENDORSED]

What are the exceptions for chromium and copper that we need to know?
by David Zhang 1B
Sat Jul 06, 2019 8:00 pm
Forum: Properties of Electrons
Topic: Electron Penetration
Replies: 2
Views: 150

Electron Penetration

What does it mean for an electron to penetrate the nucleus? In 1E.5 (b), it says that an electron in an s-orbital can penetrate the nucleus of an atom.
by David Zhang 1B
Sat Jul 06, 2019 11:10 am
Forum: Balancing Chemical Reactions
Topic: Balancing Equations
Replies: 6
Views: 153

Re: Balancing Equations

I think it's easier to focus on one element at a time, usually starting with the element that only appears once on both sides. You equalize the amount on both sides with coefficients and then you see how that coefficient affects the other element amounts. Once you've figured that out, you just simpl...
by David Zhang 1B
Fri Jul 05, 2019 10:31 am
Forum: Student Social/Study Group
Topic: Lecture July 5
Replies: 2
Views: 149

Re: Lecture July 5

I would appreciate a picture of today's notes as well. A picture of Wednesday's notes would be an extra bonus. My email is davidzhang211@yahoo.com. Thanks in advance!
by David Zhang 1B
Thu Jul 04, 2019 3:57 pm
Forum: Einstein Equation
Topic: unit of energy
Replies: 1
Views: 98

Re: unit of energy

It's a unit of energy. In Joules, it's about 1.602x10-19 J.
by David Zhang 1B
Thu Jul 04, 2019 12:20 pm
Forum: Photoelectric Effect
Topic: Threshold Energy
Replies: 2
Views: 115

Re: Threshold Energy

You would use the equation: total energy of photon= threshold energy + kinetic energy. You would need to find/be given the energy of the photon and the kinetic energy in order to determine the threshold energy.
by David Zhang 1B
Thu Jul 04, 2019 10:16 am
Forum: Photoelectric Effect
Topic: Metals and Electrons
Replies: 3
Views: 163

Re: Metals and Electrons

I don't think there would be any change in the structural properties of the metal with a change in the electrical charge.
by David Zhang 1B
Thu Jul 04, 2019 10:11 am
Forum: Photoelectric Effect
Topic: kinetic energy of electron
Replies: 8
Views: 239

Re: kinetic energy of electron

There is only a certain amount of energy in a photon. If there is more energy than is needed to release the electron, then the extra energy is kinetic. If the energy to release the electron is the exact same as the photon, then there is 0 kinetic energy.
by David Zhang 1B
Wed Jul 03, 2019 5:35 pm
Forum: Heisenberg Indeterminacy (Uncertainty) Equation
Topic: Wednesday Lecture [ENDORSED]
Replies: 1
Views: 153

Wednesday Lecture [ENDORSED]

I missed the lecture for today (Wednesday). Could somebody give me a basic summary of what topics the professor went over?
by David Zhang 1B
Wed Jul 03, 2019 12:50 pm
Forum: Student Social/Study Group
Topic: Test 1
Replies: 1
Views: 139

Test 1

How was Test 1 for you all? I wasn't able to make it that day to take the test. What was the average difficulty of the problems? Were they multiple choice, short answer, or both?
by David Zhang 1B
Mon Jul 01, 2019 8:22 pm
Forum: Limiting Reactant Calculations
Topic: Are these important? [ENDORSED]
Replies: 3
Views: 176

Re: Are these important? [ENDORSED]

It's just a standard for the experiment environment since some reactions may change under certain pressures and temperatures.
by David Zhang 1B
Fri Jun 28, 2019 10:03 pm
Forum: Einstein Equation
Topic: E=hv
Replies: 20
Views: 613

Re: E=hv

The professor only mentioned metals when talking about the photoelectric effect. Can it happen to other materials as well?
by David Zhang 1B
Thu Jun 27, 2019 7:15 pm
Forum: Balancing Chemical Reactions
Topic: Combustion Equation
Replies: 18
Views: 668

Re: Combustion Equation

The equation should be balanced so that there are the same elements on both side of the equation. If there is nitrogen present in the fuel, it would also be present in one of the products of the combustion equation.
by David Zhang 1B
Wed Jun 26, 2019 11:42 pm
Forum: SI Units, Unit Conversions
Topic: Use of Kelvin
Replies: 6
Views: 190

Re: Use of Kelvin

0 degrees Kelvin is the lowest theoretical possible temperature.
by David Zhang 1B
Wed Jun 26, 2019 8:23 pm
Forum: Molarity, Solutions, Dilutions
Topic: Homework Problem G.13 in Fundamentals
Replies: 3
Views: 134

Re: Homework Problem G.13 in Fundamentals

You first have to find the concentration of the diluted solution. You can find the moles of the initial solution since they give you the molarity of the solution and an initial volume of 1 Liter. Since molarity is moles per volume, the initial solution has 0.20 moles.When the florist adds water, the...
by David Zhang 1B
Wed Jun 26, 2019 7:55 pm
Forum: Empirical & Molecular Formulas
Topic: G.17 7th edition
Replies: 1
Views: 98

Re: G.17 7th edition

If you're looking at the solution manual for that problem, they use Liters as the unit of measurement. 250 mL is .250 Liters.
by David Zhang 1B
Wed Jun 26, 2019 7:52 pm
Forum: Accuracy, Precision, Mole, Other Definitions
Topic: Balancing Equations
Replies: 4
Views: 139

Re: Balancing Equations

I would keep everything at whole numbers just to be safe. I haven't seen any chemical equations that have decimals or fractions as the stoichiometric coefficient.
by David Zhang 1B
Tue Jun 25, 2019 8:38 pm
Forum: Accuracy, Precision, Mole, Other Definitions
Topic: Dot in chemical formula
Replies: 2
Views: 140

Dot in chemical formula

What does a dot in a chemical formula mean such as in problem E.23 when it asks about Na2CO3 (dot) 10H2O?
by David Zhang 1B
Tue Jun 25, 2019 8:22 pm
Forum: Molarity, Solutions, Dilutions
Topic: G.5
Replies: 3
Views: 159

Re: G.5

You first have to convert the 2.111g of the solid sodium carbonate into mmol of Na+. I used dimensional analysis to do the conversion. Then you can take that answer to set up a proportion since you know that n/v = n/v. You know the values of mmol and volume for the initial solution and the mmol for ...

Go to advanced search