Unit 1: Structure And Properties Of Matter

Question 0

Joseph Thompson

Answer 0

• experimented with cathode ray tubes
• creates a beam of small particles that make a flash of light when aimed at a screen
• he placed oppositely charged plates at either end to determine the charge
  FOUND: the beam of particles was deflected towards the + plate
  The beam must contain negative particles that can be removed from positive material

Question 1

What did john dalton find about atoms?

Answer 1

Reacted atmospheric gases
All matter is made of atoms
Atoms of the same element have the same average mass, size and unique properties
Atoms cannot be converted chemically into other elements
Atoms form in whole number ratios

Question 2

Ernest Rutherford 1911

Answer 2

Shot positively charged alpha particles from radioactive elements at a thin piece of gold
FOUND: most + particles went through but other deflected back causing him to believe they hit a small positive centre called the nucleus filled with protons
He was wrong because like charges repel and the nucleus could not be solid

Question 3

Niels Bohr

Answer 3

Mathematically determined where electrons were by Einstein’s light theory and max plank’s specific energy amount theory
Atomic emission spectra
Believed electrons are only found in specific allowable energy levels that represent fixed circular paths around the nucleus
In orbit, electrons do not gain or lose energy
An electron changes orbits but emitting or absorbing energy

Question 4

Ernest Rutherford 1920

Answer 4

Calculated the average mass of protons it would take to balance the negative charge of electrons
Found that atoms weighed significantly more than his calculations
Found there must be another particle that caused the extra weight but must be neutral in charge do that they don’t upset the charge balance in the atom

Question 5

Werner Heisenberg

Answer 5

Proposed the uncertainty principle: it is impossible to measure the position and momentum of an electron at the same time
The more accurately one property is measured, the less accurate the other one is measured
Proved Bohr’s model wrong because he assigned fixed paths and definite energy levels

Question 6

Louis De Broglie

Answer 6

Believed all matter behaved like waves
Developed an equation to determine the wave length of any object like an atom
An electron moving in the first energy level has a larger wave length than the radius of the atom
Meaning the electron doesn’t wave around in a circle, it’s actually outside of the orbit that Bohr said it should be in

Question 7

Erwin schrodinger

Answer 7

Quantum mechanical model: Incorporates the wave like characteristics of electrons
Applied wave theory to Bohr’s model to determine the location of the electrons using Bohr’s energy levels
Created an equation which allowed him to predict the location of an electron using statical probability
Created the region of probability orbitals where the electron would most likely be 95% of the time
These are not the electron paths

Question 8

Quantum numbers

Answer 8

Orbitals have a variety of sizes and shapes depending on the amount of energy the electron has

Question 9

Principle quantum number (n)

Answer 9

Orbital size & energy level
Higher the n value, the larger the orbital and the energy the electrons have
Periodic table periods are set up by n value

Question 10

Orbital shape quantum number l

Answer 10

Each value of l represents an energy sub level and describes a specific orbital shape 
L=0 s-shaped 
L= 1 p-shaped 
L= 2 d-shaped
L= 3 f-shaped

Question 11

Magnetic quantum number ml

Answer 11

Describes the orientation or plane of the orbital shape

Question 12

Quantum spin number ms

Answer 12

Wolfgang Pauli said electrons can only occupy an orbital with opposite spins to balance their repulsive forces
Can only equal +1/2 or -1/2

Question 13

Atomic orbitals and their relative energy order

Answer 13

1s _
2s _
2p _ _ _
3s _
3p _ _ _
4s _
3d _ _ _ _ _
4p _ _ _

Question 14

Pauli exclusion principle

Answer 14

No two electrons in an atom can have the same set of quantum numbers

Question 15

Aufbau principle

Answer 15

Building up process
Each set if quantum numbers is the same ad the last element in the order of the periodic table with one last electron tacked on in the lowers possible energy level

Question 16

Hund’s rule

Answer 16

Each orbital with the same amount of energy receives one electron before pairing
When electrons are added singly to orbitals they must have the same spin of +1/2

Question 17

Condensed electron configurations

Answer 17

Take ground state electron configuration

Take previous noble gas in square bracket and add extra electrons needed

Question 18

Excited state

Answer 18

When electrons are given energy they move into orbits of higher energy
Even though previous orbit is not filled, it jumps to a higher energy level
Ex. Copper is usually in an excited state
[Ar] 4s1 3d10
Should be 4s2 3d9
Copper is more stable with a full 3D shell and therefore becomes excited to increase stability

Question 19

Intramolecular vs. intermolecular forces

Answer 19

InTRAmolecular: electrostatic attractions inside of compounds to hold atoms together in molecules

InTERmolecular: electrostatic attractions between 2 or more molecules of ions

Question 20

Ionic bonds

Answer 20

Metal loses electron which requires an input of energy = less stable
Non metal gains electron and releases energy = regains stability
Ionic bonds form in three dimensions known as crystal lattices which causes the ions to be held into place which causes a loss in kinetic energy and becomes more stable

Question 21

Covalent bonds

Answer 21

Atoms are brought close enough together to overlap 2 partially filled orbitals which creates a region where the electrons would be 95% of the time
The 2 nuclei and 2 electrons move to a position where their repulsive forces balance called optimal particle separation this restricts movement and slows down electrons causing a release in bond energy and as a result the atoms become more stable

Question 22

Metallic bonds

Answer 22

Metals exist in pure solid form so they make bonds between themselves
Metal atoms do not gain electrons nor do they have enough valence to share to make covalent bonds
Arnold summerfeld proposed the free electron model: cations are packed into a crystal lattice held together by delocalized valence electrons which causes them to slow down and release energy
Metallic bond strength increases the smaller the metal atom and the more free electrons they can produce

Question 23

Ion dipole forces

Answer 23

Attraction between a full charge ion and the opposite slight charge of a polar molecule

Question 24

Hydrogen bond

Answer 24

Occurs between 2 polar molecules where o-h n-h or f-h group on one molecule attracts the lone pair of an o, n or f on a neighbouring molecule
Strong slight charge + strong slight charge

Question 25

Dipole dipole

Answer 25

Two polar molecules where opposite slight charges attract

Question 26

Ion induced dipole

Answer 26

An ion brought close to a non polar molecule causes electrons to displace and the non polar molecule becomes temporarily polar (iron in blood)

Question 27

Dipole induced dipole

Answer 27

A polar molecule is brought close to a non polar molecule and causes electron to displace and the non polar compound becomes temp. Polar

Question 28

LDF

Answer 28

Shared electrons are constantly vibrating which temporarily causes a charge imbalance
This temporary dipole can induce surrounding molecules
LDF forces increase with size and surface area

Question 29

Valence shell electron pair repulsion theory (VsEPR)

Answer 29

Each pair of electrons repels each other so they are as far apart as possible

Question 30

Linear arrangement

Answer 30

BA: 180

Molecular shape: linear

Question 31

Triganol planar arrangement

Answer 31

3 electron groups
BA: 120
Shape: Triganol planar or v shaped

Question 32

Tetrahedral arrangement

Answer 32

4 electron group
BA: 109.5
Shape: tetrahedral, Triganol pyramidal, v shaped

Question 33

Triganol bipyramidal arrangement

Answer 33

5 electron groups
BA: 90, 120
Shape: Triganol bipyramidal, seesaw, T shaped, linear

Question 34

Octahedral arrangement

Answer 34

6 electron groups
BA: 90, 90
Shape: octahedral, square pyramidal, square planar

Question 35

Symmetrical and different arms

Answer 35

Polar

Question 36

Asymmetrical and arms the same

Answer 36

Polar

Question 37

Symmetrical and same arms

Answer 37

Non polar

Question 38

Atomic solids

Answer 38

Made of noble gases 
London dispersion 
Extremely low melting point
Extremely soft 
No charges so can't conduct 
Low solubility in water due to dipole induced dipole

Question 39

Non polar molecular solids

Answer 39

Stacked non polar molecules
LDF
Low to medium melting point depending on size
Soft
No charges so not conductive
Low solubility due to dipole induced dipole

Question 40

Ionic solids

Answer 40

Ionic bonds
High melting point 
Hard 
Can't conduct as a solid charges can't move 
Ion dipole some dissolve some don't

Question 41

Network solid

Answer 41

Atoms or compounds linked by covalent bonds 
Covalent bonds 
High melting point 
Hard repeated geometric pattern 
No charge so can't conduct
Dipole induced dipole low solubility

Question 42

Polar molecular solid

Answer 42

Stacked polar molecules so slight opposite charges attract
Dipole dipole or HB depending on compound
Medium Melting point
Medium hardness
Can’t conduct stuck in crystal lattice
Medium to medium high solubility

Question 43

Metallic solids

Answer 43

Free electron model
Metallic bond
Medium to high melting point
Medium high hardness
Electrons can move medium to high conductivity
Ion dipole with water but doesn’t happen (forks)