Search found 25 matches

by Heung Ching Chia 1E
Sun Jun 10, 2018 12:04 am
Forum: Bronsted Acids & Bases
Topic: 12.17
Replies: 1
Views: 167

Re: 12.17

I think you find out whether it is an acidic, basic, or amphoteric oxide by looking at the periodic table as illustrated in the diagram below. Hope this helps!
by Heung Ching Chia 1E
Sat Jun 09, 2018 11:07 pm
Forum: Accuracy, Precision, Mole, Other Definitions
Topic: Molar Mass
Replies: 5
Views: 251

Re: Molar Mass

The grams per mole value (i assume you mean molar mass) would be 32gmol^-1 if you're converting from grams to moles for O2.
by Heung Ching Chia 1E
Sat Jun 09, 2018 11:00 pm
Forum: Hybridization
Topic: sigma vs pi bonds
Replies: 4
Views: 229

Re: sigma vs pi bonds

I hope this comparison table helps!
Sigma bonds have a head on overlap compared to pi bonds which overlap sideways. Pi bonds also restrict rotation while sigma bonds allow free rotation around the bond.
by Heung Ching Chia 1E
Sun Jun 03, 2018 3:00 pm
Forum: Dipole Moments
Topic: Different types of dipole moments?
Replies: 3
Views: 173

Re: Different types of dipole moments?

A dipole moment is when atoms in a molecule share electrons unequally. This occurs when one atom is more electronegative than another. By different types, do you mean a dipole-dipole and dipole-induced-dipole interaction? Dipole dipole is a type of intermolecular attraction, which is a attraction be...
by Heung Ching Chia 1E
Sun Jun 03, 2018 2:42 pm
Forum: Shape, Structure, Coordination Number, Ligands
Topic: Ligands
Replies: 8
Views: 245

Re: Ligands

Ligands are lewis bases that donate a lone pair to the central transition metal in a complex to form a coordinate bond. That is why it needs at least one lone pair of electrons or it has no lone pair to donate to the central atom.
by Heung Ching Chia 1E
Sun Jun 03, 2018 2:40 pm
Forum: Hybridization
Topic: Hybridization
Replies: 3
Views: 122

Re: Hybridization

Hybridization is the mixing of atomic orbitals to form new orbitals with different energies and shapes than the original orbitals. I think the mixing of the different types of atomic orbitals allows the atom to form more equal energy bonds and thus the result is a more stable molecule. To determine ...
by Heung Ching Chia 1E
Sun May 27, 2018 11:47 pm
Forum: Formal Charge and Oxidation Numbers
Topic: Formal Charge Exponent
Replies: 5
Views: 379

Re: Formal Charge Exponent

Hello, I am not too sure what your question means but I think the overall charge on a molecule like SO4^2- means when you add up all the formal charges of the individual atoms in the molecule, the final answer should equal 2-. For example (just an example!), if all the formal charges of O is 0 but S...
by Heung Ching Chia 1E
Sun May 27, 2018 11:38 pm
Forum: Octet Exceptions
Topic: 3.61
Replies: 4
Views: 340

Re: 3.61

ICl4- has 36 electrons in total. You first form a skeletal structure (with iodine (least electronegative atom) as your central atom)and so there are 4 single bonds connecting the iodine to each chlorine and that means you used up 8 electrons (28 e- left). You then add 6 electrons to each chlorine at...
by Heung Ching Chia 1E
Sun May 27, 2018 11:30 pm
Forum: Ionic & Covalent Bonds
Topic: Most covalent or ionic character
Replies: 3
Views: 306

Re: Most covalent or ionic character

Most covalent means the difference in electronegativity between the two atoms in a molecule is small while most ionic means the difference in electronegativity is big between two atoms.
by Heung Ching Chia 1E
Mon May 21, 2018 12:08 am
Forum: Dipole Moments
Topic: lone pairs
Replies: 3
Views: 112

Re: lone pairs

I believe it is only the shared electrons that will have partial charges due to differences in electronegativity which contributes to dipole moments. Therefore, I don't think lone pairs contribute towards dipole moments.
by Heung Ching Chia 1E
Mon May 21, 2018 12:07 am
Forum: Lewis Structures
Topic: How do I start a Lewis structure?
Replies: 3
Views: 127

Re: How do I start a Lewis structure?

The least electronegative atom should be the central atom. You then draw the skeletal structure of the molecule by adding a single bond to connect all atoms in the molecule together. You then subtract this from the total number of valence electrons you have. You can then try to arrange the valence e...
by Heung Ching Chia 1E
Sun May 20, 2018 11:47 pm
Forum: Ionic & Covalent Bonds
Topic: Octet rule
Replies: 17
Views: 460

Re: Octet rule

Q: When we do break the octet rule, is there any specific way to add electrons? A: After the third period/row, the octet rule can be broken because of the electrons in the d-block. There is no specific way to add electrons I believe. It is just counting the number of total valence electrons and tryi...
by Heung Ching Chia 1E
Sun May 20, 2018 11:23 pm
Forum: Electronegativity
Topic: Electronegativity vs. Electron affinity
Replies: 7
Views: 262

Re: Electronegativity vs. Electron affinity

To answer your second question, the central atom is usually the atom with the lowest electronegativity as the central atom is the one that shares more electrons than the non-central atoms. The higher the electronegativity, the less the atom wants to share electrons with another atom. Therefore, the ...
by Heung Ching Chia 1E
Sun May 13, 2018 6:23 pm
Forum: Lewis Structures
Topic: Lewis Structure [ENDORSED]
Replies: 3
Views: 110

Re: Lewis Structure [ENDORSED]

I think there really isn't a way to know beforehand. The first step is to count valence electrons available in the molecule and then the second step is to attach the atoms to each other with single bonds to form a skeletal structure. From then on, it kind of is trial and error. You just have to plac...
by Heung Ching Chia 1E
Sun May 13, 2018 5:57 pm
Forum: Formal Charge and Oxidation Numbers
Topic: Formal charge purpose
Replies: 33
Views: 1186

Re: Formal charge purpose

Yes, it is desirable for molecules to have the lowest energy lewis structure possible so that it can have the most stable structure. The lower the formal charge for the molecule overall and also for the individual atoms themselves, the more stable the structure.
by Heung Ching Chia 1E
Sun May 13, 2018 5:53 pm
Forum: Resonance Structures
Topic: Bonds or Lone Pairs more important?
Replies: 7
Views: 414

Re: Bonds or Lone Pairs more important?

I don't think there is a general rule as to whether you should add lone pairs or double bonds between atoms to the central atom to achieve a stable octet of electrons. It just depends on the molecule itself and what would make a structure with the lowest formal charge possible for the lewis structur...
by Heung Ching Chia 1E
Sun May 06, 2018 9:15 pm
Forum: Trends in The Periodic Table
Topic: Atomic radii and ionization energy
Replies: 1
Views: 76

Re: Atomic radii and ionization energy

Atomic energy decreases across a period because there will be constantly an addition of 1 proton versus an addition of 1 electron, and the strength of the pull of the proton on the electrons (electrostatic attraction) will outweigh the electron repulsion between electrons, hence, the radius of an at...
by Heung Ching Chia 1E
Sun May 06, 2018 2:10 pm
Forum: Photoelectric Effect
Topic: Test #2 Question 7 [ENDORSED]
Replies: 2
Views: 173

Re: Test #2 Question 7 [ENDORSED]

The question asks for the max wavelength or lowest energy, meaning when you shine the light on the metal surface, an electron just gets enough energy to be popped out onto the surface of the metal, but there will not be any extra energy for the electron to have kinetic energy. Therefore, you should ...
by Heung Ching Chia 1E
Sun May 06, 2018 2:04 pm
Forum: Trends in The Periodic Table
Topic: The Ionization energy of Oxygen
Replies: 2
Views: 93

Re: The Ionization energy of Oxygen

The general trend is ionization energy increases across a period due to the increased pull from the nucleus (+ve charge) as you are adding electrons to the same principal shell so it will be harder to remove electrons across the period. However, oxygen is one of the exceptions. This is because nitro...
by Heung Ching Chia 1E
Sun Apr 15, 2018 7:53 pm
Forum: SI Units, Unit Conversions
Topic: L35, What is t? (Conversion)
Replies: 3
Views: 137

Re: L35, What is t? (Conversion)

Yep, I am pretty sure t stands for ton, and the conversion is 1000kg= 1 ton(t)
by Heung Ching Chia 1E
Sun Apr 15, 2018 7:52 pm
Forum: SI Units, Unit Conversions
Topic: writing out conversions in one long line vs. steps
Replies: 16
Views: 560

Re: writing out conversions in one long line vs. steps

If you're talking about unit conversions within the same step, I would write it out in one long line to make sure I know which units are cancelling with which. However, if there are different separate steps required for the problem, I would write it out in steps to present my work more clearly durin...
by Heung Ching Chia 1E
Sun Apr 15, 2018 7:47 pm
Forum: Accuracy, Precision, Mole, Other Definitions
Topic: Which mass of oxygen should be used? [ENDORSED]
Replies: 23
Views: 907

Re: Which mass of oxygen should be used? [ENDORSED]

Good practice would be to use 15.999. But in exam conditions, when you might not have enough time to type in a lot of decimal places/digits, I asked my TA and she mentioned that she would not deduct points as long as your working out is correct and showed and also as long as the final answer is very...
by Heung Ching Chia 1E
Sun Apr 15, 2018 7:43 pm
Forum: Balancing Chemical Reactions
Topic: Balancing Chemical Equations and Combustion
Replies: 7
Views: 299

Re: Balancing Chemical Equations and Combustion

Combustion reactions will always have carbon dioxide (CO2) and water (H20) as its products. Whatever substance is being combusted with will always react with oxygen to be combusted (i.e. O2 will always be a reactant). You can then balance your equation normally.
by Heung Ching Chia 1E
Sun Apr 15, 2018 7:38 pm
Forum: SI Units, Unit Conversions
Topic: Length Units
Replies: 15
Views: 494

Re: Length Units

Yes, you should use SI units unless otherwise specified explicitly in the question.
by Heung Ching Chia 1E
Sun Apr 15, 2018 7:36 pm
Forum: SI Units, Unit Conversions
Topic: Avogadro's Number [ENDORSED]
Replies: 11
Views: 406

Re: Avogadro's Number [ENDORSED]

I believe avogadro's number can be used to convert both from moles to atoms and from moles to molecules.

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