Chem Part 2

Intermolecular Bonding

-Refers to bond between molecule and neighboring molecules

-Normally weaker than Intramolecular

Polarity

-Measure of unequal sharing of electrons as result of different electronegativities

Partial Changes in Polarity

-Uneven distribution results in atoms having partial changes

-More electronegativity = stronger pull to electrons

Polarity of diatomic molecules

-Symmetrical molecules are non-polar

-Asymmetrical molecules are polar

VESPR Shapes (memorise shapes)

-Tetrahedral

-Trigonal Pyramidal

-Bent

-Linear

-Trigonal Planar

Percipitation Reactions

-A reaction between two soluble ionic substances that forms a solid product

-The solid product is called a precipitate

Solubility

Is the maximum amount of solute that will be dissolved in a known quantity of a solvent at a given temperature

Molarity

- Measure for concentration in terms of number of moles in substance per litre

Non-polar Polyatomic molecules

-Covalent Bonds are non-polar if molecule is symmetrical

-Pull of electrons are equal in opposite directions the dipoles cancel each other out

-Even distribution of electrical charge

Polar Polyatomic molecules

-In asymmetrical molecules the individual dipoles of the covalent bonds do not cancel each other out making in not dipole

-Uneven distribution of electrical charge

Soulability

-Maximum amount of a solute that can be dissolved in a given quantity of a solvent at a certain temperature

Dissociation

-The process of separating positive and negative ions from a solid ionic compound to form hydrated ions when an ionic compound dissolves in water

Soluble table

In book

Kinetic Molecular Theory

-Gas particles are in constant, random motion

-Have very little attraction to one another

-Space between particles is large

Pressure

-Increases when there is an increase in number of collisions because the gas particles have more kinetic energy hence they move rapidly

Temperature

-As temp of a closed system increases, average energy of the system also increases

-Unit for temp is Kelvin (K) degrees + 273K = K

Volume

-The volume the gas occupies is always constant = Fixed volume

-Volume is not constant = Variable volume

Gas Laws in Book

-Gay-Lussac's Law

-Charles Law

-Boyle's Law

Aqueous solutions and molarity

A mixture of solute dissolved in water

Concentration

A measure of number of particles in a specified volume of soloution

Concentrated Soloution

A solution containing many particles per unit volume of soloution

Dilute Soloution

Soloution containing few particles per unit volume of soloution

Saturation

Unsaturated: A soloution that can dislove more soloute

Saturated: A soloution in which no more soloute can disolve

Supersaturated: soloution that has been heated to disolve more soloute, but on cooling after a disturbance crystals of the solvent are produced

What is behavior of gas affected by?

-Pressure

-Temp

-Volume

Standard Temp and Pressure

Standard Temp = 273K

Standard Pressure = 100kPa

Gas Law

P x V = n x R x T

p = pressure in kPa

V = volume in L

n = mdes

T = Temp in K

R = Universal constant 8.313k Mol

Precipitation Reactions

-Reaction between 2 soluble ionic substances that forms a solid product

Structure of an Atom

Charges of Particles

Neutron - Neutral

Electron - Negative

Proton - Positive

Periodic Table Groups

Electron Configuration

Practice

What is atomic mass number with decimal?

Total number of protons + average number or neutrons

Properties of Metal Elements

-Good conductors of heat and electricity

-Shiny

-Ductile

-Can be pounded to thin (malleable)

Properties of non-metal elements

-Poor conductors of heat and electricity

-Not ductile or malleable

-Brittle and break easy

-Dull

-Most are gases

Ionic Bonding

Practice

A positive and negative bond

A metal and non-metal bonding

Metal gives and electron to non-metal

Covalent

2 negatives bonding

A non-metal and non-metal bonding

Non-metals share electrons

Usually gases or liquids

Don't conduct electricty

Factors that affect reaction rate

-Concentration of moles - lower concertation- slower

-Pressure - Lower pressure - further away

-Surface area and catalysts - If surface area increases -more area to react

-Temperature - Colder is slower- Can't move as quick

Required of chemical reaction

-Particles need to collide

-Activation energy

-Connect oreintation

Balancing Reactions

Practice

Numerals for covalent

1-Mono, 2-Di, 3-Tri, 4-Tetra, 5-Penta, 6-Hextra, 7-Hepta, 8-Octa, 9-Nona, 10-Deca

Metallic Character

-Elements become less metallic as you move across the periodic table

Atomic Radius

-The distance from the nucleus of an atom to the outermost electron shell

-Becomes smaller as you go across and upwards as there are more positive electrons which means more shells creating a bigger shape

Ionisation Energy

-Energy required to remove an electron from gaseous atom

-Increases as you go up and across because more shells as you go down meaning more spread out and can take it easier

Electronegativity

-A measure of an atoms ability to attract electrons in a chemical bond

-Increases as you go up and across because more shells as you go down meaning more spread out and can take it easier

Ionic Radius

-Radius of an ion

-When it becomes positive or negative it looses size

Diatomic Molecules

Ex. H2, N2, O2, F2, Cl2, Br2, I2\

-All non-metallic gases (except noble) will form covalent bonds with themselves to be a diatomic

-Never single

Practice Electron Dot Diagram vs Lewis Structure

Naming Covalent Compounds

Step 1: Name first non-metal as an element

Step 2: Name 2nd non-metal as ide at the end

Step 3: Put the numeral in front of both numbers mono doesn't go in front of first

How to find electrons and neutrons

Neutrons = mn - an

Electrons + protons = an

exothermic reaction

releases energy (heat)

negative

lower product energy

endothermic reaction

absorbs energy

positive

higher product energy

Acid

Chemical compound that donates an hydrogen atom

Base

Chemical compound that accepts an hydrogen atom

Arrehenius Model

-Acids can produce high concentration of hydrogen ions in aq solution

-Acids increase concentration of hydrogen ions in water while bases increase hydroxide ions

Concentration of acids + bases

Diluted soloution will contain less soloute than same volume of concentrated solution

pH scale

6.9 and below = acid

7 = neutral

7.1 and above = basic

Hydrogen ions in pH

Low pH values have high concentration of hydrogen ions

Chromatography

Technique that can be used for qualitive or quanative analysis, as it identifies both components in mixture and how much

The two phases of Chromotography

Mobile: Solvent moves through stationary phase

Stationary: A substance that stays still

RF Value

Distance travelled by substance / distance travelled by solvent

Intermolecular Forces

-Attraction between molecules not bonds

-Three types - Dispersion, Dipole-Dipole and Hydrogen Bonding

Dispersion Forces

-Occur between covalent polar and non-polar

-Contain valance electrons that constantly move therefore are weak as only create dipole-dipole bond for short time period

Dipole-dipole Forces

-Attractions between oppositely charged regions of polar molecules

Hydrogen Bonding

-specific dipole-dipole bond where a positive hydrogen atom bonded to a F, O or N

-Strongest out of all bonds