1. STATE OF MATTER
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What is Brownian Motion?
All matter is made of tiny particles.
The particles are atoms, ions, or molecules.
In a liquid or gas, the particles move at random.
The random motion of particles is called Brownian Motion.
It can be seen by looking at smoke particles in the air through a microscope.
•The gas molecules move at high speed colliding with other molecules.
•In doing so they continually change their velocity (speed and direction), giving rise to the
observed Brownian motion or random walk behavior.
2. Atoms, elements and compounds
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proton number/ atomic number is the number of protons in the nucleus of an atom of the same
element
mass number/nucleon number is the total number of protons and neutrons in the nucleus of an
atom of the same element
What is an isotope?
Atoms of the same element with the same number of electrons and protons but a di erent
number of neutrons
Chemical properties (how they react) are mostly determined by the number of electrons, hence
chemical properties are identical
Physical properties are mostly determined by the atomic mass, so these change
Why do isotopes have the same chemical properties?
The same number of electrons
Why do isotopes have di erent physical properties?
Di erent number of neutrons, di erent atomic mass
Atoms with the same number of electrons in their outermost shell belong to the same group in the
periodic table
The period number determines how many shells there are
The number of electrons in the outermost shell determines the way the element will react
(chemical properties)
Noble gases have a full outer shell (stable) and, therefore are very unreactive
The electrons orbit around the nucleus of the atom in di erent Energy Levels or Shells
The shells ll up in order, the lowest energy level (innermost shell) lls up rst
1st Shell – Maximum 2 Electrons
2nd Shell – Maximum 8 Electrons
3rd Shell – Maximum 8 Electrons
4th Shell – Maximum 18 Electrons
•Atoms with an incomplete outer shell are unstable
•They can easily react with other atoms by losing, gaining, or sharing electrons
•When they lose or gain electrons they form IONS
•Ions are atoms that have lost or gained electrons and have a charge as well as a full outer shell
•Atoms in the same group in the periodic table have the same number of electrons in their outer
shell; they want to lose or gain the same number of electrons to become stable
The octet rule refers to the tendency of atoms to prefer to have eight electrons in the valence
shell.
ionic lattice: positive and negative ions [1] regular pattern / opposite charges closer than the same
charge [1]
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The positive and negative ions formed by the complete transfer of electrons are strongly attracted
to each other. This electrostatic attraction is called ionic bonding.
Lattice: /repeated/ pattern/ framework / periodic / ordered/ alternating/organized; (of) particles/
atoms / molecules/ions / cations/anions; v
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Silicon dioxide has a similar structure as diamond tetrahedral.
Metallic bonding marking scheme: positive ions or cations NOT atoms or cores or nuclei layers or
lattice or regular pattern delocalised or free or mobile electrons or sea
OR
positive ions or cations NOT atoms or cores or nuclei attraction between ions and electrons
delocalized or free or mobile electrons or sea the attraction/electrostatic bonding must be between
ions and delocalized electrons, between cations and anions does not score ACCEPT bond if
quali ed - electrostatic bond, etc. if molecular or molecules then cannot score cation mark
3. Stoichiometry
The relative atomic mass (Ar) of an element is the average mass of the isotopes of an element compared
to 1/12th of the mass of an atom of Carbon -12
The relative molecular mass(Mr) of a substance is the sum of the relative atomic masses of the
elements present in the molecule
Relative formula mass (Mr) in the case of ionic compounds
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In a chemical reaction, one of the reactants is often added
in excess and is not completely used up in the reaction.
The amount of product formed is determined by the amount
of reactant that is not in excess and so is used up
completely in the reaction.
This is called the limiting reactant.
Explain which of the reactants is in excess.
Use the balanced equation:
CaCO3 + 2HNO3 → Ca(NO3)2 + H2O + CO2
There are 2 mol of HNO3 for 1 mol of CaCO3
0.063 mol of CaCO3 would need:
2 ´ 0.063 = 0.126 mol HNO3 to react and only
0.1 mol is present.
So CaCO3 is in excess and HNO3 is the limiting
reactant.
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4. Electrochemistry
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5.Chemical energetics:
Exothermic:
Endothermic:
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6.Rate of reaction
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7. Acids and bases
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8. Periodic table
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9.Organic chemistry:
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10. Expermintal technique and chemical analysis
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