Lewis Structures/VSEPR Theory/Forces/Organic Compounds

Question 1

Rules for drawing Lewis structures,

Answer 1

1) calculate the number of valence electrons

2) draw the central atoms with the rest of the atoms around. The central atom will be the first one listed unless hydrogen is first, then it will be second.

3) start with a single bond between each element. Complete o tets for each atoms. Hydrogen and helium are exceptions.

4) confirm that your drawing has the correct number of valence electron.
If you have too many try double and triple bonds. If you don’t have enough overfill the central atom.

Start filling outer electrons but stop when u run out of electrons then use bonds to fill the centre.

Question 2

Valence electrons?

Answer 2

Electrons in the outer shell of an atom that are the only ones that bind.

Question 3

What are some exceptions to Lewis structures and VSEPR theory?

Answer 3

Transition metals and lanthanides and actinides

Question 4

Octet?

Answer 4

Full outer shell of 8 electrons.

Question 5

What is a bond?

Answer 5

A bond is equal to two electrons and you count them once.

Question 6

What is VSEPR Theory?

Answer 6

The simplest model for modelling atom is bonding.
This resists the geometry of individual molecules from the # of electron pairs surrounding their central atoms.

Question 7

What does VSEPR stand for?

Answer 7

VALENCE
DHELL
ELECTRON
PAIR
REPULSION

Question 8

what leads to distinct molecular shapes?

Answer 8

Take your Lewis structure and count electron regions around the central atom.

Each region is a negatively charged region. It will repulse other negatively charged regions.

We look at central atom only and the number of bonds, not the type.

However the negative regions can’t completely get away from each other because the nucleus of the central atom is holding them in.

Question 9

Facts about carbon?

Answer 9

Carbon prefers to be full with bonds
Carbon is the basis of all life
We have parent chains of Carbon

Question 10

What are intramolecular forces?

Answer 10

Covalent bonds involve electron sharing between atoms.

When atoms in a bond equally, the bonding electrons are shared equally.

Question 11

Why is bond type important? Why is electronegativity important?

Answer 11

Bond type predicts the characteristics of molecules.

Electronegativity is the tendency of an atom in a molecule to attract the shared pair of electrons towards itself. The atom with the higher electronegativity attracts the electrons to itself so it has a more negative charge than the atoms with less electronegativity. Electronegativity difference decides bond type.

Question 12

Intramolecular forces? Types of bonds? Electron facts?

Answer 12

Atoms pull electrons differently.
Covalent bonds involve sharing electrons between atoms.

Non-polar covalent bonds: when atoms in the bond pull equally, bonding electrons are shared equally.

Polar covalent bonds: (polar bonds are covalent). A bond where electrons are shared unequally. The more electronegative atom attracts more strongly and gains a slightly negative charge. The less electronegative atom has a slightly positive charge.

Ionic bond: electronegativity difference is so large that the atom with the higher electronegativity take the electrons rather than share them. Electrons are pulled away from a string attraction, they aren’t just hanging out.

Electrons come in pairs and there’s always and even number of valence electrons.

Question 13

Intermolecular forces?

Answer 13

Molecules attract each other with a number of different forces.

Intermolecular attractions are weaker than ionic or covalent bonds.

These forces contribute to determining whether a compound will be a solid, liquid, or gas, at a given temperature.

Question 14

Van der Waals Forces?

Answer 14

The two weakest attraction between molecules.

Question 15

Linder dispersion forces?

Answer 15

The weakest of all intermolecular forces caused by the motion of electrons.

When moving electrons happen to be momentarily more on the side of a molecule closest to a neighbouring molecule, their electric force influence the neighbouring molecules electrons to be momentarily more on the other side. This causes a short attraction between the two molecules.

All molecules exhibit LDF.

Question 16

Dipole dipole interactions?

Answer 16

When polar molecules are attracted to one another as the slightly positive end of one molecule is attracted to the negatively charged end of the other.
They don’t bond, just stick together.

Dipole interactions are similar but weaker than ionic bonds.

These interactions occur in polar and ionic, just not non-polar.

Intermolecular forces attract molecules together so they don’t wanna be separated easily. Like water and how it has high surface tension.

Question 17

A hydrogen bond (H-bonding)?

Answer 17

A weak type of force that forms a special type of dipole/dipole interaction.

When an H atom bonds to a strongly electronegative atom in the back it’s of another electronegative atom with a lone pair of atoms.

These bonds are stronger than ordinary dipole dipole and dispersion forces, but weaker than true covalent and ionic bonds.

H bonding happens when hydrogen is bonded with O N or F as they have high electronegativity values.

Question 18

What are organic compounds?

Answer 18

All carbon containing compounds with the exception of:

Carbon oxides, carbides, carbonates (these are in organic compounds)

In organic compounds, carbon atoms are usually bonded to hydrogen, oxygen, nitrogen, sulfer, phosphorus, and halogen atoms.

Question 19

Hydrocarbons:

Answer 19

The simplest organic compounds are hydrocarbon, which contain hydrogen and carbon.

Hydrogen will have a full valence shell with 2 electrons.

Classes of hydrocarbons: Alkanes, Alkenes, Alkynes.

Question 20

Alkanes?

Answer 20

Hydrocarbons that have only single bonds between atoms.

Relationship between number of carbon atoms and hydrogen atoms: CnH2n+2

Alkanes could be straight chained or branch chained alkanes.

Question 21

Straight chain alkanes?

Answer 21

All straight chain alkanes have the suffix -ane and begin with a prefix telling how much carbon atoms are present.

Question 22

Like structure?

Answer 22

We know it’s single bonds and follows the formula.

Lines are single bonds between carbon atoms. The number of carbon atoms is the number of corners.

Question 23

What parts of the name do straight chain alkanes have? Why?

Answer 23

Two parts: first name and family name

They only have a straight chain of single bonds and no branches.

First name is the number of carbons.

Last name is the type of chain or family, so alkanes for example.

Question 24

Does the angle matter between bonds?

Answer 24

If you can trace the carbon chain without lifting in the middle, you have one continuous parent chain so don’t get tricked by angles between carbon atoms.

Question 25

Branched chain alkanes:

Answer 25

In straight chain-alkanes, you don’t have to lift your pencil but in branched chain alkanes, you do.

Both straight chain and branched chain have the same molecular formula.

Therefore the name of an organic compound must describe the molecular structure of the compound accurately.

Question 26

Naming branch chained alkanes?

Answer 26

1. Count the number of carbon atoms in the longest continuous chain (the parent chain). Use the name of the straight-chain alkane with that number of carbon atoms.
2. Number each carbon atom in the parent chain. Locate the end carbon closest to a substituent group. Label that carbon position 1.
3. Name each alkyl group constituent. The names of these groups are placed before the name of the parent chain.
4. If the same alkyl group occurs more than once as a branch on the parent structure, use a prefix to indicate how many times it appears.
5. Whenever different alkyl groups are attached to the same parent structure, place their names in alphabetical order.
6. Write the entire name using hyphens to separate numbers from words and commas to separate numbers.

Question 27

What is a branch?

Answer 27

Another carbon group that doesn’t flow with our straight chain.

Question 28

What is a parent chain?

Answer 28

Always the longest chain that can be drawn continuously. Identify junction, the point with many chains coming out of it then identify the longest prices to get parent chain.

Question 29

Naming alkenes?

Answer 29

Unsaturated hydrocarbons with one more more double covalent bonds between carbon atoms in the chain

CnH2n

Question 30

Naming Alkynes?

Answer 30

Unsaturated hydrocarbons that contain one more triple covalent bonds between carbon atoms in the chain.