Search found 30 matches

by breannasung_1K
Mon Jun 04, 2018 3:37 pm
Forum: Shape, Structure, Coordination Number, Ligands
Topic: 4 ligands shape?
Replies: 6
Views: 182

Re: 4 ligands shape?

When we want to know just the general shape of the structure, we have to consider all regions of electron density, including lone pairs. Many times, when there are 4 regions of electron density the shape is tetrahedral. When we want to know the molecular structure, we have to consider how the lone p...
by breannasung_1K
Mon Jun 04, 2018 3:04 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Lone pairs
Replies: 5
Views: 165

Re: Lone pairs

Lone pairs are still considered a region of electron density. Lone pairs actually occupy more space than bonds, therefore affecting the bond angles of other atoms in the molecule.
by breannasung_1K
Mon Jun 04, 2018 3:03 pm
Forum: Lewis Structures
Topic: Test Q.8 [ENDORSED]
Replies: 7
Views: 270

Re: Test Q.8 [ENDORSED]

The circled structure has the shorter bond lengths because there is one less oxygen present. because there is one less oxygen present, there are fewer electrons and less electron repulsion pushing the oxygens away from each other. with less electron repulsion, the central atom is able to hold onto t...
by breannasung_1K
Thu May 31, 2018 10:31 am
Forum: Determining Molecular Shape (VSEPR)
Topic: VSEPR AXE
Replies: 4
Views: 140

Re: VSEPR AXE

For the VSEPR model, I am pretty sure E records the number of LONE PAIRS surrounding the central atom.
by breannasung_1K
Thu May 31, 2018 10:26 am
Forum: Hybridization
Topic: σ bonds
Replies: 9
Views: 258

Re: σ bonds

sigma bonds occur when there is an overlap between atomic orbitals. 1 single covalent bond is a sigma bond.
by breannasung_1K
Thu May 31, 2018 10:24 am
Forum: Hybridization
Topic: Octahedral shape
Replies: 1
Views: 86

Re: Octahedral shape

The atoms surrounding the central atoms contribute to the octahedral shape. You have to think about the shape in 3 dimension rather than just planar. The link below better illustrates how six bonds/regions of electron density lead to the octahedral shape.
http://www.chemtube3d.com/VSEPRShapeSF6.html
by breannasung_1K
Sat May 26, 2018 5:23 pm
Forum: Resonance Structures
Topic: ranking
Replies: 11
Views: 467

Re: ranking

You rank the resonance structures based off the formal charges you find for each atom in the structure. The structure with the formal charge of 0 for the central atom is the most stable.
by breannasung_1K
Sat May 26, 2018 5:13 pm
Forum: Determining Molecular Shape (VSEPR)
Topic: Regions of electron density
Replies: 7
Views: 234

Re: Regions of electron density

Lone pairs around the central atom are considered a single region of electron density, and when looking at the VSPER model, we are only considering the electron densities around the central atom
by breannasung_1K
Sat May 26, 2018 5:11 pm
Forum: Lewis Structures
Topic: 3.45
Replies: 3
Views: 147

Re: 3.45

There could many resonance structures for a particular molecule, but the ones that are most the stable and have the lowest energy are the ones they are probably looking for.
by breannasung_1K
Sun May 20, 2018 12:29 am
Forum: Ionic & Covalent Bonds
Topic: Electron affinity [ENDORSED]
Replies: 6
Views: 198

Re: Electron affinity [ENDORSED]

Electron affinity is the how likely an atom is to gain an electron, and ionization energy is the energy required to remove an electron. Electron affinity therefore increases as you go across the periodic table because the effective nuclear charge is increasing. Effective nuclear charge is dependent ...
by breannasung_1K
Sun May 20, 2018 12:25 am
Forum: Lewis Structures
Topic: Charge on Molecule [ENDORSED]
Replies: 4
Views: 155

Re: Charge on Molecule [ENDORSED]

You have to find the formal charge on every molecule in the compound, and only then will you be able to tell which molecule is contributing to the overall positive or negative charge.
by breannasung_1K
Sun May 20, 2018 12:24 am
Forum: Resonance Structures
Topic: How does a resonance structure work?
Replies: 10
Views: 295

Re: How does a resonance structure work?

Resonance structures are lewis structures of the same compound, but the bonds may be arranged differently. However, all resonance structures still represent the same compounds.
by breannasung_1K
Mon May 14, 2018 2:10 am
Forum: Lewis Structures
Topic: Dots or lines [ENDORSED]
Replies: 5
Views: 173

Re: Dots or lines [ENDORSED]

I am pretty sure that it is fine to use a line to represent 2 electrons as opposed to drawing the two dots every time.
by breannasung_1K
Mon May 14, 2018 2:08 am
Forum: Electronegativity
Topic: Trends? [ENDORSED]
Replies: 10
Views: 567

Re: Trends? [ENDORSED]

we have gone over: atomic #, # of shells, atomic radius, effective nuclear charge, electronegativity, first ionization energy and electron affinity.
by breannasung_1K
Mon May 14, 2018 2:05 am
Forum: Ionic & Covalent Bonds
Topic: VALENCE ELECTRONS [ENDORSED]
Replies: 16
Views: 461

Re: VALENCE ELECTRONS [ENDORSED]

knowing that the first shell is occupied by 2 electrons, i subtract 2 from the atomic number, which tells how many electrons an atom has. All the elements in a column have the same number of valence electrons.
by breannasung_1K
Mon May 07, 2018 12:22 pm
Forum: Wave Functions and s-, p-, d-, f- Orbitals
Topic: F orbital
Replies: 6
Views: 303

Re: F orbital

the F subshell has 7 orbitals, and therefore can hold 14 electrons. I dont think we need to be too familiar with the F subshell fro the midterm.
by breannasung_1K
Mon May 07, 2018 12:19 pm
Forum: Electron Configurations for Multi-Electron Atoms
Topic: 3d before 4s
Replies: 9
Views: 267

Re: 3d before 4s

the 4s orbital is lower in energy, and therefore electrons fill the 4s orbital first before 3d. However, when you are writing the electron configuration, it is conventional to write 3d before 4s.
by breannasung_1K
Mon May 07, 2018 12:16 pm
Forum: Trends in The Periodic Table
Topic: Stability of Cl vs Cl-
Replies: 6
Views: 220

Re: Stability of Cl vs Cl-

After Cl gains another electron, it has an octet. This means Cl- is more stable and less reactive because it now has a full set of valence electrons. Cl- will no longer look for more electrons.
by breannasung_1K
Mon May 07, 2018 12:14 pm
Forum: Trends in The Periodic Table
Topic: Trends to Know
Replies: 12
Views: 468

Re: Trends to Know

It might be best to know the trends for electron affinity. Electron affinity increases as ionization energy increases.
by breannasung_1K
Mon May 07, 2018 12:11 pm
Forum: Wave Functions and s-, p-, d-, f- Orbitals
Topic: spd orbitals and electron config.
Replies: 3
Views: 161

Re: spd orbitals and electron config.

I am pretty sure you would have to use the element from the previous row and continue with the electron configuration, if you wanted to use the noble gas electron configuration. But if you are unsure, it might be best to just write down the full electron configuration.
by breannasung_1K
Mon May 07, 2018 12:07 pm
Forum: Trends in The Periodic Table
Topic: Ionization Energy (2.61) [ENDORSED]
Replies: 2
Views: 136

Re: Ionization Energy (2.61) [ENDORSED]

ionization energy is the energy needed to remove an electron. First ionization energy refers to the energy needed to remove the FIRST electron.
by breannasung_1K
Fri Apr 20, 2018 3:44 am
Forum: General Science Questions
Topic: Notation
Replies: 3
Views: 346

Re: Notation

I don't think it really matters. For me personally, it is easier to use m/s as opposed to ms^-1, especially dealing with a problem that has many units. It is easier for me to visualize which units cancel each other out.
by breannasung_1K
Fri Apr 20, 2018 3:42 am
Forum: Photoelectric Effect
Topic: Threshold Energy [ENDORSED]
Replies: 12
Views: 352

Re: Threshold Energy [ENDORSED]

Threshold energy is the amount of energy needed to remove an electron from the metal.
by breannasung_1K
Fri Apr 20, 2018 3:35 am
Forum: Empirical & Molecular Formulas
Topic: Test #1 Question
Replies: 7
Views: 372

Re: Test #1 Question

You have to count the number of atoms there are for each element and make those numbers subscripts for their associated elements (this will give you the molecular formula). And to find the empirical formula, you simplify the subscripts.
by breannasung_1K
Thu Apr 12, 2018 2:01 am
Forum: Molarity, Solutions, Dilutions
Topic: Mass percentage
Replies: 8
Views: 351

Mass percentage

How do you do a mass percentage problem if the percentages for the given elements do not equal 100?
by breannasung_1K
Thu Apr 12, 2018 1:56 am
Forum: Limiting Reactant Calculations
Topic: M1 hw
Replies: 3
Views: 170

Re: M1 hw

For this problem, you need to find the molar mass of just NH3, NOT 2NH3.
by breannasung_1K
Thu Apr 12, 2018 1:46 am
Forum: Accuracy, Precision, Mole, Other Definitions
Topic: Accuracy vs Precision
Replies: 23
Views: 742

Re: Accuracy vs Precision

Precision is how close the measurements/ data are to one another. Accuracy is the closeness of the measurements/ data to their correct values.

When you have high precision and low accuracy, you can multiply all your data by some value to get higher accuracy.
by breannasung_1K
Thu Apr 12, 2018 1:42 am
Forum: SI Units, Unit Conversions
Topic: why do I not use avogadro's number
Replies: 5
Views: 231

Re: why do I not use avogadro's number

Avogadro's number means 1 mol of something = 6.0221x10^23 molecules or atoms of something, so to say you only use Avogadro's number when you are given mols is not a correct.
by breannasung_1K
Thu Apr 12, 2018 1:39 am
Forum: SI Units, Unit Conversions
Topic: Moles mols mol? [ENDORSED]
Replies: 21
Views: 1220

Re: Moles mols mol? [ENDORSED]

Moles, mols and mol all mean the same thing.
by breannasung_1K
Fri Apr 06, 2018 5:12 pm
Forum: SI Units, Unit Conversions
Topic: What is the notation for molar mass?
Replies: 15
Views: 598

Re: What is the notation for molar mass?

The unit for molar mass is M (g/mol).

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