Search found 40 matches

by katrinawong3d
Sun Nov 24, 2019 11:37 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: t shape and see saw
Replies: 6
Views: 40

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).
by katrinawong3d
Sun Nov 24, 2019 11:33 pm
Forum: Shape, Structure, Coordination Number, Ligands
Topic: Complexes
Replies: 2
Views: 29

Re: Complexes

A complex always has a central metal atom or ion that is bonded to a ligand(s).
by katrinawong3d
Sun Nov 24, 2019 11:28 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Bond Angles
Replies: 7
Views: 56

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).
by katrinawong3d
Sun Nov 24, 2019 11:23 pm
Forum: Dipole Moments
Topic: benzene polarity
Replies: 4
Views: 40

Re: benzene polarity

In general, all hydrocarbons are nonpolar.
by katrinawong3d
Sun Nov 24, 2019 11:11 pm
Forum: Shape, Structure, Coordination Number, Ligands
Topic: Cis vs Trans
Replies: 21
Views: 263

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.
by katrinawong3d
Fri Nov 15, 2019 9:24 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: bent v. straight shape
Replies: 3
Views: 42

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.
by katrinawong3d
Fri Nov 15, 2019 9:21 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: test 2
Replies: 13
Views: 106

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.
by katrinawong3d
Fri Nov 15, 2019 9:20 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: T Shape
Replies: 7
Views: 60

Re: T Shape

There's still one more slide that he's going to cover on Monday, so maybe he'll cover it then?
by katrinawong3d
Fri Nov 15, 2019 9:18 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: VSEPR Notation
Replies: 5
Views: 45

Re: VSEPR Notation

A refers to the central atom, X refers to the number of bonds, and E refers to the lone pairs.
by katrinawong3d
Fri Nov 15, 2019 9:16 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: seesaw
Replies: 9
Views: 83

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.
by katrinawong3d
Sun Nov 10, 2019 11:46 pm
Forum: Electronegativity
Topic: oxygen vs nitrogen electronegativity
Replies: 3
Views: 53

Re: oxygen vs nitrogen electronegativity

Actually, Oxygen is more electronegative than Nitrogen as it is the second most electronegative element.
by katrinawong3d
Sun Nov 10, 2019 11:41 pm
Forum: General Science Questions
Topic: Sig Figs
Replies: 7
Views: 111

Re: Sig Figs

It depends on the TA grading your test. Some are more lenient with sig figs while others aren't.
by katrinawong3d
Sun Nov 10, 2019 11:40 pm
Forum: Dipole Moments
Topic: Dipole Moment
Replies: 6
Views: 45

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.
by katrinawong3d
Sun Nov 10, 2019 11:28 pm
Forum: Dipole Moments
Topic: H Bonding
Replies: 4
Views: 38

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.
by katrinawong3d
Sun Nov 10, 2019 11:24 pm
Forum: Photoelectric Effect
Topic: Light acts as a wave
Replies: 4
Views: 105

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.
by katrinawong3d
Sun Nov 03, 2019 8:37 pm
Forum: Electron Configurations for Multi-Electron Atoms
Topic: 4s or 3d first?
Replies: 14
Views: 195

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.
by katrinawong3d
Sun Nov 03, 2019 8:23 pm
Forum: Sigma & Pi Bonds
Topic: Quantum Numbers
Replies: 9
Views: 85

Re: Quantum Numbers

Quantum numbers describe the state of an electron. There are 4 quantum numbers: n, l, ml, and ms.
by katrinawong3d
Sun Nov 03, 2019 8:18 pm
Forum: Electronegativity
Topic: size
Replies: 8
Views: 46

Re: size

Atomic radius increases as you move down and left of the periodic table, whereas electronegativity increases as you move right and up.
by katrinawong3d
Sun Nov 03, 2019 8:02 pm
Forum: Lewis Structures
Topic: Which element at center of the structure
Replies: 6
Views: 44

Re: Which element at center of the structure

The most electronegative element goes in the middle.
by katrinawong3d
Sun Nov 03, 2019 8:00 pm
Forum: Electronegativity
Topic: Electronegativity and ionic/covalent bond
Replies: 2
Views: 23

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.
by katrinawong3d
Sun Oct 27, 2019 5:12 pm
Forum: Electron Configurations for Multi-Electron Atoms
Topic: Exceptions to Electron Configuration
Replies: 7
Views: 57

Re: Exceptions to Electron Configuration

I think Cr and Cu are the only exceptions.
by katrinawong3d
Sun Oct 27, 2019 4:44 pm
Forum: Electron Configurations for Multi-Electron Atoms
Topic: Exceptions
Replies: 2
Views: 27

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.
by katrinawong3d
Sun Oct 27, 2019 4:38 pm
Forum: Electron Configurations for Multi-Electron Atoms
Topic: Effective Nuclear Charge
Replies: 4
Views: 38

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.
by katrinawong3d
Sun Oct 27, 2019 4:29 pm
Forum: Ionic & Covalent Bonds
Topic: Valence Electrons
Replies: 16
Views: 165

Re: Valence Electrons

valence electrons = the element's group number
by katrinawong3d
Sun Oct 27, 2019 4:27 pm
Forum: Properties of Light
Topic: p=mv
Replies: 4
Views: 44

Re: p=mv

momentum = mass x velocity has units of kg m/s = kg x m/s
by katrinawong3d
Sun Oct 20, 2019 8:53 pm
Forum: Properties of Light
Topic: What are the units of hertz
Replies: 41
Views: 339

Re: What are the units of hertz

number of cycles per second (s^-)
by katrinawong3d
Sun Oct 20, 2019 8:50 pm
Forum: DeBroglie Equation
Topic: h bar
Replies: 2
Views: 43

Re: h bar

H bar is a reduced Planck's constant, which is h/2pi.
by katrinawong3d
Sun Oct 20, 2019 8:48 pm
Forum: Properties of Electrons
Topic: Spin
Replies: 5
Views: 76

Re: Spin

Electron spin is the intrinsic angular momentum of an electron.
by katrinawong3d
Sun Oct 20, 2019 8:44 pm
Forum: Properties of Electrons
Topic: Energy of Electron
Replies: 3
Views: 60

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.
by katrinawong3d
Sun Oct 20, 2019 8:32 pm
Forum: *Shrodinger Equation
Topic: Negative sign in Equation
Replies: 4
Views: 47

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.
by katrinawong3d
Sun Oct 13, 2019 8:05 pm
Forum: Photoelectric Effect
Topic: Photoelectric Effect
Replies: 4
Views: 47

Re: Photoelectric Effect

The photoelectric effect has to be done in a vacuum because it allows all frequencies to reach/travel to the sample.
by katrinawong3d
Sun Oct 13, 2019 8:01 pm
Forum: Accuracy, Precision, Mole, Other Definitions
Topic: Angstrom's Constant
Replies: 5
Views: 114

Re: Angstrom's Constant

You would multiply by tens to get smaller units.
by katrinawong3d
Sun Oct 13, 2019 7:56 pm
Forum: Photoelectric Effect
Topic: De Broglie's Equation
Replies: 5
Views: 35

Re: De Broglie's Equation

Use it when you have mass and velocity and need wavelength.
by katrinawong3d
Sun Oct 13, 2019 7:53 pm
Forum: Einstein Equation
Topic: E=hv
Replies: 5
Views: 69

Re: E=hv

Yes, you can, but it also depends on the context/given information of the problem.
by katrinawong3d
Sun Oct 13, 2019 7:47 pm
Forum: DeBroglie Equation
Topic: Constructive vs. Destructive Interference
Replies: 5
Views: 47

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.
by katrinawong3d
Thu Oct 03, 2019 10:58 pm
Forum: Accuracy, Precision, Mole, Other Definitions
Topic: Aqueous, solid, gas
Replies: 11
Views: 167

Re: Aqueous, solid, gas

It depends on the context of the problem.
by katrinawong3d
Thu Oct 03, 2019 10:44 pm
Forum: Properties of Light
Topic: Spectroscopy
Replies: 4
Views: 70

Re: Spectroscopy

Blue light has more energy and a shorter wavelength, and thus oscillates more(higher frequency) than red light.
by katrinawong3d
Thu Oct 03, 2019 10:25 pm
Forum: Balancing Chemical Reactions
Topic: Combustion
Replies: 12
Views: 191

Re: Combustion

To add on, water and carbon dioxide is produced as a gas.
by katrinawong3d
Thu Oct 03, 2019 10:11 pm
Forum: SI Units, Unit Conversions
Topic: When to use what units
Replies: 5
Views: 103

Re: When to use what units

For calculations to find molarity, you have to use liters and moles.
by katrinawong3d
Thu Oct 03, 2019 10:07 pm
Forum: SI Units, Unit Conversions
Topic: 2.Mass Percentage and Decimal Rounding:
Replies: 10
Views: 86

Re: 2.Mass Percentage and Decimal Rounding:

Agreed with the previous answer, I would match the sig figs and round at the end.

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