Unit/Sem 1 Exam Chemistry (Add with other tests from test 2 to get Sem 2)) Flashcards
What is an Alpha Particle?
2 protons
2 neutrons
Rutherford’s problem
- Failed to account for the loss of energy (radiation) due to the circular motion of electrons
- Collision of electrons with nucleus
John Daltons Theory
Atoms of different elements have different properties
James Chadwick’s Discovery, Experiment name
Discovered the neutron. Beryllium Bombardment
Line Absorption Spectra - Gas Example
- Light passed through gas will have particular wavelengths (colors) missing, as light of that colour was to excite the electrons and is absorbed by the atoms in the gas.
The removed wavelengths do not appear on the continuous (white light) wavelength absorption spectrum
Light Emission - Return to ground state
Electrons emit the same frequencies that excited them when returning to ground state, but in all different direction so reduced intensity.
Relative atomic mass
Relative Atomic Mass is defined as the ratio of the average mass of an atom (taking into account all isotopes and their natural abundances) compared to a 1/12 a Carbon-12 atom
Atomic mass
Number of protons and neutrons added together
Atomic number
Number of protons in the atom of an element
What ions do non-metal atoms usually form; explain?
Negative ions: high electronegativity
Purpose of Mass Spectrometer
Determine relative abundances and presence of isotopes in an element’s sample
What is Nanotechnology?
A nanomaterial is something has single units that exist at the nanoscale
What is the nanoscale?
Nanoscale refers to materials that are between 1 to 100 nanometers across
What are Nanoparticles?
Nanoparticles are a specific type of nanomaterials that are spherical and at the nanoscale (1-100 nm). Greater surface area so tends to be more reactive
Types of real-life nanoparticles
Cosmetics and creams, sunscreen containing metal nanoparticles that reflect sunlight,
Three main types of Carbon Nanomaterials
- Graphene
- Carbon Nanotubes
- Buckminster Fullerenes or Bucky Balls
Structural Isomers with more branching means…
Less dispersion force: and lower boiling points
Aromatics
Compounds found to contain a 6-carbon cyclical group attached to various other functional groups with parent compound benzene (C6H6)
Alkyl groups
Alkanes that are missing a hydrogen like Ethyl (C2H5)
Cis and Trans meanings? For Alkanes or Alkenes? Think
Cis means same elements are on same sides
Trans means same elements are diagonally opposite
Only for Alkenes (Double bond)
Hydroxide in organic chem means
Alcohol group -ol
Cyclical prefix (not aromatic)
Cyclo-
The term aromatics refers to
Alternating cyclical double and single bonds
What group of Aliphatics undergo combustion and when? What does it form?
Alkenes and Alkenes undergo combustion when there is a plentiful supply of oxygen to form carbon dioxide and H20 and heat energy (J)
Incomplete combustion occurs when there is? What is formed?
Incomplete combustion occurs when there is a limited air supply - Carbon monoxide is formed along with less energy
Substitution reactions in alkanes or benzene occur when?
Spontaneous Reaction? Why?
What is the product called?
Occurs when an alkane or benzene is reacted with a halogen (Cl2 or Br2 or I2). Causes swapping of one or more Hydrogen atom with one or more Halogen atom
Reaction is very slow due to high energy required. Uses a UV catalyst (high energy)
The product is called a haloalkane
Hydrogenation Addition Reactions occurs in what and when?
Outline the process
Hydrogenation occurs in alkenes when there is H2 (Hydrogen gas) and an alkene. When these are heated in the presence of a metal catalyst like nickel, the hydrogen atoms add on to the alkene and the double bonds turn into single bonds, making it saturated (alkane)
Halogenation Addition Reactions occurs in what and when?
Outline the process
Halogenation reactions occur in alkenes when there are 2 Halogen atoms (Like Cl2, I2, or Br2) reacting with an alkene. The halogen atoms add on to the alkene and the double bonds turn into single bonds, making it a saturated haloalkane
Hydration Addition Reactions occurs in what and when?
Outline the process
Reaction of alkenes with water (strong acid catalyst - sulfuric acid) to produce an alcohol
What is Markovnikoff’s rule
When HCl, HBr, or HI react by addition, the Hydrogen atom attaches to the carbon atom already having the most hydrogen atoms on carbon chain. Non-hydrogen atoms however add to the carbon chain with the smallest number of hydrogen atoms.
Hydrohalogenation Addition Reactions occurs in what and when?
Outline the process
Hydrogen halides (HCl, HBr, HI) also react with alkene (saturated hydrocarbon). Makes it a single bond and adds halogen onto carbon chain with lowest number of hydrogens (Markovnikoff’s rule), and Hydrogen adds on to carbon chain with highest number of hydrogens
What is activation energy?
The energy required to break the bonds in the reactants for the chemical reaction to occur
Requirements for an exothermic and endothermic reactions
For a reaction to be exothermic, more energy must be released that supplied. For a reaction to be endothermic, a reaction must have more energy supplied than released.
Example exothermic and endothermic reaction
Exothermic - Combustion of gasoline
Endothermic - Cooking
Endothermic reaction makes the object feel…Reason?
Cold; Due to drop in temperature of substance
Exothermic reaction makes the object feel…Reason?
Hot; Due to Rising temperature of substance
Endothermic reaction may be written like this
REACTANTS + ENERGY
—> PRODUCTS
Exothermic reaction may be written like this
REACTANTS
—> PRODUCTS + ENERGY
What is Enthalpy?
What is change in enthalpy?
What is change in enthalpy of exothermic and endothermic
Enthalpy (H) is the total amount of energy in a substance
Enthalpy of reactants to products
Exothermic enthalpy change: -
Endothermic enthalpy change: +
What is a Fuel (Chemically)?
A substance that has a large amount of energy in it. Released by combustion
Which hydrocarbons are Natural Gases (Fossil Fuels) mainly made out of?
Methane (CH4) but also some ethane (C2H6)
Three main types of biofuels
- Biogas
- Bioethanol
- Biodiesel
Bioethanol (process, name, and formula)
Fermentation of sugars from plant materials
C6H12O6(aq) -> 2CH3Ch2OH(aq) + 2CO2(g)
Biogas Description of process
Anaerobic bacteria take the complex carbohydrates and proteins and break down into Carbon Dioxide (CO2) and Methane (CH4)
What determines the amount of energy that is released from the combustion of a fuel?
The amount of carbon
What is Energy Content?
The chemical energy of a substance is called the energy content.
What is a fuel’s enthalpy change?
Heat of combustion when a specific amount is burnt
Energy Content Formula
Energy content = n x Heat of Combustion
Are biofuels renewable? Are fossil fuels renewable
Biofuels: Yes
Fossil Fuels: No
Are fossil fuels toxic?
Yes. Toxic ingredients and byproducts
Why are biofuels environmentally friendly?
Because the carbon emissions from burning biofuels are almost equally absorbed by regrown plants
Are Carbon Dioxide emissions for fossil fuels and biofuels both high?
Yes
Physical Properties of Alkanes
Uses?
Less Dense than water
Insoluble in water
Good solvent for other organic compounds
Fuels or Paraffin Wax
Physical Properties of Cycloalkanes
Liquids or Soft Solids at room temperature
Virtually insoluble in water.
Properties of Alkenes
Denser than water
C2 to C4 are volatile gases
After C4 is liquids or soft solids
