Search found 40 matches
- Sun Nov 24, 2019 11:37 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: t shape and see saw
- Replies: 6
- Views: 417
Re: t shape and see saw
Seesaw (AX4E) shape has a lone pair whereas trigonal bipyramidal doesn't (AX5). A tetrahedral(AX4) has no lone pairs whereas a tshape has 2 lone pairs(AX3E2).
- Sun Nov 24, 2019 11:33 pm
- Forum: Shape, Structure, Coordination Number, Ligands
- Topic: Complexes
- Replies: 2
- Views: 189
Re: Complexes
A complex always has a central metal atom or ion that is bonded to a ligand(s).
- Sun Nov 24, 2019 11:28 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: Bond Angles
- Replies: 7
- Views: 472
Re: Bond Angles
Bond angles can be smaller than the ideal 109.5 value because each electron density/group exerts a slightly different repulsion (lone pairs vs. bonding pair).
- Sun Nov 24, 2019 11:23 pm
- Forum: Dipole Moments
- Topic: benzene polarity
- Replies: 4
- Views: 433
Re: benzene polarity
In general, all hydrocarbons are nonpolar.
- Sun Nov 24, 2019 11:11 pm
- Forum: Shape, Structure, Coordination Number, Ligands
- Topic: Cis vs Trans
- Replies: 22
- Views: 1618
Re: Cis vs Trans
Cis molecules are polar since they have the same bonds on one side, which doesn't cancel out. Trans molecules are nonpolar since they have the same bonds on opposite sides, which cancel each other out.
- Fri Nov 15, 2019 9:24 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: bent v. straight shape
- Replies: 3
- Views: 262
Re: bent v. straight shape
A bent shape is a result of an electron pair pushing the two bonds down. Thus, the model with the lone pair is the one with a bent shape.
- Fri Nov 15, 2019 9:21 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: test 2
- Replies: 13
- Views: 649
Re: test 2
I might be wrong, but I'm pretty sure Professor Lavelle said in class today that hybridization will not be on the test.
- Fri Nov 15, 2019 9:20 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: T Shape
- Replies: 7
- Views: 497
Re: T Shape
There's still one more slide that he's going to cover on Monday, so maybe he'll cover it then?
- Fri Nov 15, 2019 9:18 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: VSEPR Notation
- Replies: 5
- Views: 279
Re: VSEPR Notation
A refers to the central atom, X refers to the number of bonds, and E refers to the lone pairs.
- Fri Nov 15, 2019 9:16 pm
- Forum: Determining Molecular Shape (VSEPR)
- Topic: seesaw
- Replies: 9
- Views: 623
Re: seesaw
A seesaw shape is when there are 4 bonding pairs and 1 lone pair (AX4E). For example, sulfur tetrafluoride, SF4, would have a seesaw shape.
- Sun Nov 10, 2019 11:46 pm
- Forum: Electronegativity
- Topic: oxygen vs nitrogen electronegativity
- Replies: 3
- Views: 1669
Re: oxygen vs nitrogen electronegativity
Actually, Oxygen is more electronegative than Nitrogen as it is the second most electronegative element.
- Sun Nov 10, 2019 11:41 pm
- Forum: General Science Questions
- Topic: Sig Figs
- Replies: 7
- Views: 423
Re: Sig Figs
It depends on the TA grading your test. Some are more lenient with sig figs while others aren't.
- Sun Nov 10, 2019 11:40 pm
- Forum: Dipole Moments
- Topic: Dipole Moment
- Replies: 6
- Views: 314
Re: Dipole Moment
I think most molecules have some sort of a dipole-dipole force. It depends on factors like bond symmetry and electronegativity difference.
- Sun Nov 10, 2019 11:28 pm
- Forum: Dipole Moments
- Topic: H Bonding
- Replies: 4
- Views: 258
Re: H Bonding
Yes, hydrogen bonding only works with fluorine, oxygen, and nitrogen because of their high electronegativity. This bonding isn't as strong as covalent bonding because it is an intermolecular force, which is weaker than an intramolecular force like covalent bonding.
- Sun Nov 10, 2019 11:24 pm
- Forum: Photoelectric Effect
- Topic: Light acts as a wave
- Replies: 4
- Views: 401
Re: Light acts as a wave
The photoelectric effect supports the particle model of light as the experiment saw that changing the intensity of light didn't eject electrons, but rather that ejection of electrons depended on the frequency of light.
- Sun Nov 03, 2019 8:37 pm
- Forum: Electron Configurations for Multi-Electron Atoms
- Topic: 4s or 3d first?
- Replies: 14
- Views: 786
Re: 4s or 3d first?
You fill the 4s shell before the 3d shell. But, I believe Lavelle wants us to write 3d first since you remove electrons from 4s first.
- Sun Nov 03, 2019 8:23 pm
- Forum: Sigma & Pi Bonds
- Topic: Quantum Numbers
- Replies: 9
- Views: 567
Re: Quantum Numbers
Quantum numbers describe the state of an electron. There are 4 quantum numbers: n, l, ml, and ms.
- Sun Nov 03, 2019 8:18 pm
- Forum: Electronegativity
- Topic: size
- Replies: 8
- Views: 448
Re: size
Atomic radius increases as you move down and left of the periodic table, whereas electronegativity increases as you move right and up.
- Sun Nov 03, 2019 8:02 pm
- Forum: Lewis Structures
- Topic: Which element at center of the structure
- Replies: 6
- Views: 498
Re: Which element at center of the structure
The most electronegative element goes in the middle.
- Sun Nov 03, 2019 8:00 pm
- Forum: Electronegativity
- Topic: Electronegativity and ionic/covalent bond
- Replies: 2
- Views: 235
Re: Electronegativity and ionic/covalent bond
Atoms with similar electronegativity usually form covalent bonds, whereas atoms with a large electronegativity difference (EN>2) form ionic bonds.
- Sun Oct 27, 2019 5:12 pm
- Forum: Electron Configurations for Multi-Electron Atoms
- Topic: Exceptions to Electron Configuration
- Replies: 7
- Views: 328
Re: Exceptions to Electron Configuration
I think Cr and Cu are the only exceptions.
- Sun Oct 27, 2019 4:44 pm
- Forum: Electron Configurations for Multi-Electron Atoms
- Topic: Exceptions
- Replies: 2
- Views: 194
Re: Exceptions
These elements are exceptions because it's easier for them to remove a 4s electron and move it to the 3d subshell, which will result in a more stable half-filled or completely filled subshell.
- Sun Oct 27, 2019 4:38 pm
- Forum: Electron Configurations for Multi-Electron Atoms
- Topic: Effective Nuclear Charge
- Replies: 4
- Views: 238
Re: Effective Nuclear Charge
The more electrons there are, the greater the shielding effect on the outermost electrons. So, since there are more electrons to repel each other, the attraction between an electron and the nucleus (nuclear attraction) decreases.
- Sun Oct 27, 2019 4:29 pm
- Forum: Ionic & Covalent Bonds
- Topic: Valence Electrons
- Replies: 16
- Views: 687
Re: Valence Electrons
valence electrons = the element's group number
- Sun Oct 27, 2019 4:27 pm
- Forum: Properties of Light
- Topic: p=mv
- Replies: 4
- Views: 133
Re: p=mv
momentum = mass x velocity has units of kg m/s = kg x m/s
- Sun Oct 20, 2019 8:53 pm
- Forum: Properties of Light
- Topic: What are the units of hertz
- Replies: 41
- Views: 1940
Re: What are the units of hertz
number of cycles per second (s^-)
- Sun Oct 20, 2019 8:50 pm
- Forum: DeBroglie Equation
- Topic: h bar
- Replies: 2
- Views: 112
Re: h bar
H bar is a reduced Planck's constant, which is h/2pi.
- Sun Oct 20, 2019 8:48 pm
- Forum: Properties of Electrons
- Topic: Spin
- Replies: 5
- Views: 192
Re: Spin
Electron spin is the intrinsic angular momentum of an electron.
- Sun Oct 20, 2019 8:44 pm
- Forum: Properties of Electrons
- Topic: Energy of Electron
- Replies: 3
- Views: 158
Re: Energy of Electron
Yes, you're correct. The energy increases because an electron absorbs energy when it moves up from n=1 to n=2.
- Sun Oct 20, 2019 8:32 pm
- Forum: *Shrodinger Equation
- Topic: Negative sign in Equation
- Replies: 4
- Views: 264
Re: Negative sign in Equation
To add on, when electrons move down an energy level, it is an exothermic reaction, which indicates a negative sign.
- Sun Oct 13, 2019 8:05 pm
- Forum: Photoelectric Effect
- Topic: Photoelectric Effect
- Replies: 4
- Views: 149
Re: Photoelectric Effect
The photoelectric effect has to be done in a vacuum because it allows all frequencies to reach/travel to the sample.
- Sun Oct 13, 2019 8:01 pm
- Forum: Accuracy, Precision, Mole, Other Definitions
- Topic: Angstrom's Constant
- Replies: 5
- Views: 345
Re: Angstrom's Constant
You would multiply by tens to get smaller units.
- Sun Oct 13, 2019 7:56 pm
- Forum: Photoelectric Effect
- Topic: De Broglie's Equation
- Replies: 5
- Views: 237
Re: De Broglie's Equation
Use it when you have mass and velocity and need wavelength.
- Sun Oct 13, 2019 7:53 pm
- Forum: Einstein Equation
- Topic: E=hv
- Replies: 5
- Views: 199
Re: E=hv
Yes, you can, but it also depends on the context/given information of the problem.
- Sun Oct 13, 2019 7:47 pm
- Forum: DeBroglie Equation
- Topic: Constructive vs. Destructive Interference
- Replies: 5
- Views: 170
Re: Constructive vs. Destructive Interference
Constructive interference is where two waves are added together, while in destructive interference, the two waves cancel each other out.
- Thu Oct 03, 2019 10:58 pm
- Forum: Accuracy, Precision, Mole, Other Definitions
- Topic: Aqueous, solid, gas
- Replies: 11
- Views: 16026
Re: Aqueous, solid, gas
It depends on the context of the problem.
- Thu Oct 03, 2019 10:44 pm
- Forum: Properties of Light
- Topic: Spectroscopy
- Replies: 4
- Views: 190
Re: Spectroscopy
Blue light has more energy and a shorter wavelength, and thus oscillates more(higher frequency) than red light.
- Thu Oct 03, 2019 10:25 pm
- Forum: Balancing Chemical Reactions
- Topic: Combustion
- Replies: 12
- Views: 710
Re: Combustion
To add on, water and carbon dioxide is produced as a gas.
- Thu Oct 03, 2019 10:11 pm
- Forum: SI Units, Unit Conversions
- Topic: When to use what units
- Replies: 5
- Views: 322
Re: When to use what units
For calculations to find molarity, you have to use liters and moles.
- Thu Oct 03, 2019 10:07 pm
- Forum: SI Units, Unit Conversions
- Topic: 2.Mass Percentage and Decimal Rounding:
- Replies: 10
- Views: 432
Re: 2.Mass Percentage and Decimal Rounding:
Agreed with the previous answer, I would match the sig figs and round at the end.