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All The Notes
Atomic # or Z Number:
Numbering of Protons & Electrons
Atomic # = P+ , e-
Ex:
- Oxygen (atomic #8), has 8 P+ and 8 e- (remember that all atoms on the periodic table have a overall charge that is neutral)
Atomic Mass/Atomic Weight/Isotopic Mass:
Protons + neutrons = atomic mass
Ex: O8
16
P+ = Atomic #
P+ = 8
N = Atomic mass - Atomic #
N = 16 - 8
N = 8
e- = Atomic #
e- = 8
Bohr-Rutherford Diagrams:
- Represent the electronic structure of an atom
- Describes the electron configuration of all the elements on the periodic table
- Like a finger print, every element on the periodic table has it own unique e- configuration
How to draw Bohr-Rutherford models:
- i) Inner circle = nucleus: which contains P+ and N
- ii) Orbital Shells = contains e-, these e- need to be dispensed accordingly.
Rule:
Ex:
Na11 K19
22 39
P+ = P+ =
N = N =
e- = e- =
Isotopes:
- Atoms of the same element with the same number of P+ and e- but different number of neutrons.
- Ex: Carbon-12 and Carbon-14
P+ = 6 P+ = 6
N = 6 N = 8
e- = 6 e- = 6
* Both types of carbon will behave chemically the same, but the difference is that one weighs more than the other.
Ex:
Hydrogen Deuterium Trit ium
H1 H1 H1
1 2 3
P+ = P+ = P+ =
N = N = N =
e- = e- = e- =
Sample problems:
Element Symbol Atomic
Number Atomic Mass # of Protons # of Neutrons # of Electrons
Oxygen 16
Na 25
6 14
O 15
Answers:
Element Symbol Atomic
Number Atomic Mass # of Protons # of Neutrons # of Electrons
Oxygen O 8 16 8 8 8
Sodium Na 11 25 11 14 11
Carbon C 6 20 6 14 6
oxygen O 8 15 8 7 8
Parts of the Atom
Protons:
- Positively charged particles (+)
- Located in the nucleus of the Atom (Centre)
- Symbol = P+
- Weight = 1 Atomic Mass Unit (AMU)
or 1 AMU = 1.66 × 10-27 kg
Neutrons:
- Neutral in charge (zero charge)
- Located in the Nucleus
- Symbol = N
- Weight = 1 AMU
Electrons:
- Negative in charge (-)
- Located outside of the nucleus
- Symbol = e-
- Weight = zero (to small to be counted)
(electron mass = 9.1 × 10-31 kg)
Nucleons:
- All subatomic particles (particles smaller than an atom) that reside in the nucleus of an atom
- Protons and Neutrons are nucleons
Shells/Orbitals:
- Regions in space surrounding the nucleus where e- are believed to exist
- Represented as concentric rings that surround the nucleus
ALL ATOMS ON THE PERIODIC TABLE ARE SAID TO BE STABLE. I.E HAVE AN OVERALL CHARGE OF ZERO. THIS MEANS THAT:
THE NUMBER OF P+ (IN NUCLEUS) = NUMBER OF e
Recognizing Acids and Bases
- We have learnt that chemical compounds are pure substances. Based on properties, compounds can be further divided into categories, such as acids and bases.
Properties that make Acids and Bases:
- Acids and Bases both react with chemical Indicators
*(Cabbage juice is an indicator, allows you to see through colour change if the substance is an acid or base)
Acids:
- Sour tasting ex: sour candies/citric acids
- Corrosive (Can burn through metal)
- When dissolved in water release H+
eg of an acid: HCl Hydrochloric acid
Bases:
- Bitter tasting
- Slippery when rubbed between fingers
- Corrosive (Can eat glass)
* Good conductors of electricity because they release OH- when they are dissolved in H2O
- ex of a base: NaOH Sodium Hydroxide = Drain cleaner
Acids and Bases: Where do they come from?
Bases:
- Always have an OH- in them
ex. NaOH Sodium Hydroxide
Acids:
- Always have an H+
ex. HCl Hydrochloric acid
Comparing Bases and Acids:
- What makes something more acidic or basic?
-This is determined by the number of OH- or H+ respectively
When comparing two bases look at the number of OH-:
NaOH vs Ba(OH)2
-Ba(OH)2 is more basic b/c it has 2 OH- as apposed to the single OH- in NaOH
When comparing two acids look at the number of H+
HCl vs H2SO4
- H2SO4 is more acidic due to the fact it has 2 H+ as apposed to the single H+ found in HCl
Dissociation:
- When acids and bases are mixed in water the return tback to atoms, this is called dissociation
ex: HCl H+ + Cl-
ex: H2SO4 2H+ + S
Neutralization:
Acids + Bases Ionic salt + H2O
Ex. 1: HCl + NaOH NaCl + H2O
Ex. 2: Ba(OH)2 + 2HF BaF2 + 2H2O
Quantities: Left vs Right
Ba 1 1
O 2 1 (therefore must multiply by 2)
H 2 x 2 2 (therefore must multiply by 2)
F 2 2
Ex. 3: 3Mg(OH)2 + 2NH3 Mg3N2 + 6H2O
*Lets work this one out together*
Chemical Reactions and Equations
Types of Chemical Reactions:
- Addition
- Decomposition
- Displacement or Substitution
- Double Displacement
Addition:
- Also known as a direct combination (A + B AB)
- Reaction in which atoms and molecules join together directly to produce larger molecules
ex: the combustion of sulfur to form sulfur dioxide
S + 02 S02
Decomposition:
- Molecule breaks down into other components (AB A + B)
ex: the decomposition of carbonic acid
H2CO3 H2O + CO2
Displacement:
- Also known as substitution (AB + C AC + B)
- Involves change of partners
ex: Liberation of bromine from calcium bromide by chlorine
Cl2 + CaBr2 CaCl2 + Br2
Double Displacement:
- involves a joint exchange of partners (AB + CD AD +CB)
ex: the precipitation of silver chloride when solutions of silver nitrate and sodium chloride are mixed
AgNO3 + NaCl AgCl + NaNO3
Acids and Bases Mixed in Water
Acids:
- Acids are the protons donors (H+)
ex: the reaction b/w HCl and H20
HCl + H20 H30+ + Cl-
- In this reaction the HCl donates the proton to H20
Bases:
- Bases are the proton acceptors
ex: the reaction b/w NH3 and H20
NH3 + H20 NH + OH-
In this reaction the NH3 accepts the proton from H20
Water:
- water (because of its neutrality) can act as either a weak acid or base depending on the other starting material
Practice Questions:
1) HCl + H2O
2) HNO3 +H2O
3) HCN +H2O
4) HS- +H2O
5) H2O +H2O
Answers:
1) HCl + H2O H3O+ + Cl-
2) HNO3 + H2O H3O+ + NO3
3) HCN + H2O H3O+ + CN-
4) HS- + H2O H3O+ + S-2
5) H2O + H2O H3O+ + OH-
LABS Physical, Chemical and Catalytical Experiments
Experiment #1: Making Your Own Cold Pack
Procedure:
- weigh out 25g of ammonium nitrate
- put the 25g of ammonium nitrate into the plastic bag
- measure out 50mL of luke warm water into a graduated cylinder
- quickly, pour the water into your bag of ammonium nitrate sealing the bag immediately afterwards (try to remove all air from bag before sealing)
- gently squeeze the bag to mix the ammonium nitrate and water
Questions: (answer all questions in full sentences on a separate piece of paper)
What is happening to the temperature of the bag?
Is this a chemical or physical reaction? Give reasons for hypothesis.
Experiment #2: Reaction in a Bag
Procedure:
- place 1tbsp of calcium chloride (CaCl2) into a plastic sealable bag
- place 1tbsp of baking soda into the bag, seal and shake gently (observe if a reaction is taking place)
- measure 10ml of indicator solution (the indicator is cabbage juice so do NOT spill it on yourself as it will stain your clothes)
- carefully add the indicator solution to the bag of CaCl2 and baking soda (flatten bag to remove all air before sealing)
- gently mix the indicator around so that it will wet all of the solid (squeezing the bag gently may help)
* - if the bag starts to get really tight due to the reaction, open it slightly to allow for the gas to release and then reseal it
* - observe the temperature of the reaction for about 2 minutes (be sure to record observations every 30 sec. in chart provided on the following page)
Questions: (answer all questions in full sentences on a separate piece of paper)
1- Did a noticeable reaction occur before the indicator was added?
2- What colour changes did the indicator go through?
3- Why does the bag inflate?
4- Initially does the reaction get cold or hot?
5- After a minute does the reaction get cold or hot?
6- Was this a chemical or physical reaction that you observed? (Provide reasons for answer)
Experiment #3: Balloon Blowing
Procedure:
- get two 50mL graduated cylinders, mark them A and B
- add 25mL of vinegar to graduated cylinder A
- add 10mL of water to graduated cylinder B and then add 15mL of vinegar to the 10ml of water (be sure to add water first)
- with the 2 balloons that you have put 2 tbsp of baking soda inside of them, do this through the mouth portion of the balloon (be sure not to get any baking soda into the vinegar at this point)
For the proceeding two steps try to do them at the same time.
- place the mouth of the balloon over the graduated cylinder so that it is snug around the neck of the cylinder
- shake the balloon to ensure that all of the powder falls from inside of the balloon and into the vinegar.
Questions: (answer all questions in full sentences on a separate piece of paper)
What is happening when the powder and vinegar mix?
Which balloon blew up faster and bigger?
What is your hypothesis for the difference between these two balloons?
Experiment #4: Antacid Tablet Race
Procedure:
- you have 2 antacid tablets
- crush one of the tablets into powder form (be sure not to contaminate or lose this powder)
- take this crushed tablet and put it into an empty cup
- take the other tablet (whole) and put it into the second cup
- fill up the two graduated cylinders to 25ml
- at the same time add the water to the two glasses and observe which tablet dissolves faster, the crushed antacid tablet or the whole one
Questions: (answer all questions in full sentences on a separate piece of paper)
In which form did the antacid dissolve faster, whole or crushed? Why?
Is this a chemical or physical reaction? Why (provide reasons)?
Experiment #5: Paper Clip Catalyst
Procedure:
-take the dollar bill sized piece of paper and fold it into thirds, in the shape of a Z
- using the big ear of the first paper clip, clip the 2 and 3 folds together
- using the big ear of the second paper clip, clip the 1 and 3 fold together
-grab the paper ends and pull quickly (but not violently)
- the paper clips should come free from the paper and be hooked together
* - the catalyst speeds up the reaction but does not become part of the reaction
Questions: (answer all questions in full sentences on another piece of paper)
1 - What acted as the catalyst in this reaction?
2 - What are the starting materials?
3 - What was the product?
Practice Quiz
Atom Quiz
1) Write the proper standard atomic notation for the following elements.
a) An atom of Beryllium with 4 protons and 5 neutrons.
b) An atom of Aluminum with 13 protons and 14 neutrons.
2) Assuming that each atom is neutral, complete the table below. /12
Atomic # Mass # Number of Protons (P+) Number of electrons (e-) Number of Neutrons (N)
8 8
23 12
16 16
29 14
3) What is an isotope (use an example to help explain your answer)?
4) Fill in the following table for the following isotopes.
Symbol Element Atomic #Atomic Mass Protons Electrons Neutrons
U
235
Iodine-131
53
27 60
Am
241
5) Draw Bohr-Rutherford diagrams and the proper standard atomic notation for the following. /18
a) Aluminum b) Potassium
c) Magnesium-25 d) Carbon-14
e) Fluorine f) Calcium
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