Chemistry Unit 2 (test 2) molecular geometrey

Covalent Bonds

when nonmetal atoms react with each other to achieve a full octet. The share electrons to form the bond.

When 2 hydrogens react what does it form?

A duet

What are dot structures?

Made of valence electrons, they will combine o create compounds that achieve the required octet.

What is the difference between dots v. lines in structures?

Dots = dot structure, Lines = structural formula or Lewis Structure

What are isomers?

When an element has multiple Lewis Structures.

What does a condensed formula tell you?

It gives you hints about how to do the structural formula, it is when the atoms are separated instead of being grouped together.

What is unique about helium?

It has one unshared pair (2 valence electrons) which is unique among noble gasses.

Nonpolar

even distributions of electrons, it is symmetrical

What are gainers?

Gainers are elements that need a lesser amount of electrons to complete their valence shell. The more they already have, the easier is for them to collect the rest they need. The best gainer is fluorine, and the lesser follow down and to the left. They stop being gainers after the Boron row.

What does the shape of an element determine?

The shape determines the properties.

Molecular Polarity

It determines the strength of IMFs

Melting Point/Boiling Point

the more polar molecules have stronger IMFs which means they will have a higher melting point. Non polar or less polar molecules have lower melting points.

Density

The shape of the molecule effects the density and how tightly the molecule can pack together as it cools off.

Solubility

Involves solvents and the amount it will dissolve. Bad IMFS dont dissolve or mix well.

Strong Imfs

example water, molecules tightly packed together

Weak Imfs

Ex. gasses, like oxygen, the molecules are more spread out and have weak bonds

What does the size of an atom depend on?

It depends on electrons

__repel, __attract

same, opposites

what does VSEPR stand for?

Valence shell electron pair repulsion theory

substituents

things that are stuck on the central atom, they must have the same amount on both sides to be symmetrical.

polar

the uneven distribution of electrons

Linear

180 bond angle, 0 uspe, symmetrical, nonpolar

trigonal planar

(no 3d shape for it) (flat) 120 bond angle, 3 bonds, 0 uspe, symmetrical, nonpolar

tetrahedral

4 bonds, 0 uspe, 109 bond angle, symmetrical, nonpolar

pyramidal

3 bonds, 1 uspe, 107 bond angle, not sym. polar

bent

2 bonds, 2 uspe, 104 bond angle, not sym. polar

covalent bond

they all have unequal sharing of electrons

what bonds equally share electrons

the 7 diatomic elements (noh7)

electronegativity

the ability to attract shared electrons, the worst and smallest are on the left, the best and biggest are f, n, o

Which metal beats which

nonmetals beat metals

do noble gasses have electronegativity

no

what has stronger bonds, a gas or liquid

a liquid, gas has weak bonds

what is the weakest imf

London Forces

what is the strongest imf

hydrogen bonds

what is the median force

dipole dipole forces

what imf is the most polar

hydrogen bonds, london forces are the weakest

what bond only happens with nonpolar

london forces

what bonds only happen with polar molecules

all of them, the most polar is hydrogen bonds

what are IMFS

the allow molecules to stick to each other

what is a dipole

a molecule with a positive and negative side

where do london forces happen and between what

they happen in the empty space between the molecules and the positive and negative forces attract

are london forces fast or slow?

fast

what does more electrons mean for the boiling point

it means the boiling point will be higher

what does a higher boiling point mean for london forces

it means there will be more or a stronger london force (or bond in general)

boiling

when a substance turns into a gas

what happens at 0 celcius

water freezes

what happens at 0 kelvin

particles stop moving

what does a higher boiling point mean for the mass

the mass is likely heavier

if there is more mass, is there more or less london force

more

what does a bigger molecule mean for bond strength?

it means the bonds are stronger

what is stronger, polar or nonpolar?

polar always

what has stronger/more bonds, a linear or flat molecule/ a ball?

the flat molecule because there is more surface

boiling point + imfs

the higher the boiling point the stronger the imf

what are the 6 factors of imf strength?

1. polar = strong, nonpolar=weak

2. perm. dipole = strong,

3. temp. dipole=weak

4. the bigger a molecule, the more electron jiggling it has, the stronger the bonds

5. the smaller a molecule the less electron jiggling it has, the weaker the bonds

6. shape (linear vs. sphere)

Does non polar or polar have dipole-dipole attractions?

polar has this

What forces occur between the positive and negative side of a 2 dipoles?

electrostatic attraction (opposite charges attract)

If there is only Cs and Hs with single bonds, is the molecule polar or nonpolar.

it is nonpolar

If an element is low on the periodic table what does that mean for its boiling point and IMFs

it means they will be higher

What molecules can a hydrogen bond form with?

Nitrogen, flourine, and oxygen

Difference between intra/intermolecular

remember, intramolecular is like a stick and intermolecular is the space between two molecule

are imfs tighter toward the top or bottom of a liquid

the top, looser at the bottom

if IMFs are strong is there more or less surface tension

more

higher mp/bp means what?

stronger imfs

do strong imfs have more or less capillary action

more

the thinner the capillary, the more or less it sucks

more

where is the tension and imfs attracted to in capillaries

the sides

what is viscosity

resistance to flow

what are examples of items with high viscosity

syrup, honey, tar, and glass

does higher vapor pressure mean more or less evaporation

more evaporation

does more evaporation lead to weaker or stronger imfs

weaker imfs

what is vapor pressure

a pressure created by evaporating gasses, the more they evaporate the more pressure it creates

what does vapor pressure measure

the amount that has evaporated

is there is more vapor pressure does this mean strong or weak imfs

it means weak imfs

in vapor pressure, if the bonds are strong, does it evaporate less or more

it evaporates less

What type of electron takes up the most space?

An unshared pair

What do electrons do according to the VSEPR theory?

electrons in their bonds repel each other, causing atoms to arrange themselves far away for each other.

What intermolecular force is responsible for the high boiling point of water?

Hydrogen Bonding

What property decreases as IMF strength increases?

Vapor pressure

If something evaporates fast the vapor pressure is?

Very high

What type of bond is more polar, ones where the elements are close together on the periodic table or far apart?

Close together is more polar

If something is more polar, is it stronger?

Yes

True or False, the more electronegative something is, the more covalent it is.

True