National Chemistry

These notes are for the Scottish National Chemistry course taught in fourth year in most Scottish schools.

The notes available here are concise notes. They are NOT to be considered as material to learn from - they are for revision.

 The notes are arranged under the following topics

National 3 Unit 1
Unit 2
Unit 3

National 4 and 5 Unit 1 Rates of Reaction
Atomic Structure
Bonding and Properties
Acids and bases

National 4 and 5 Unit 2 Fuels and Homologous Series
Consumer Products
Carbohydrates

National 4 and 5 Unit 3 Metals
Plastics
Fertilisers
Nuclear Chemistry
Chemical analysis

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National 4 and 5 Rate of Reactions

National 4
Rate of Reactions

Chemical reactions can be identified by
  (i) a change in appearance of substance
  (ii) a detectable energy change
  (iii) the formation of at least one new substance

Examples of reactions: iodine clock decomposition x

There are about 100 elements (each has a name, a symbol and an Atomic Number).
    An element has only one type of atom while a compound has at least two different types of atoms.
When different elements react together a compound is produced.

Compounds ending in "ide" usually have two different elements present, while
compounds ending in "ite" or "ate" have oxygen as a third element present.

 

Following chemical reactions - information
  Chemical reactions can be speeded up by
  (i) increasing temperature
  (ii) decreasing particle size (increasing surface area)
  (iii) increasing concentration
  (iv) using a catalyst
Further explanation

 Catalysts are substances which speed up reactions and are not used up during the
reaction - they can be recovered chemically unchanged e.g., transition metals in car
exhausts to reduce pollutant gases changing to harmless gases.
Catalysts can enable reactions to occur at lower temperatures

The 100 plus elements can be classified as
(i) solids (s), liquids (1), or gases (g)
(ii) metals or non metals
(iii) man-made (synthetic) or occurring naturally
(iv) by chemical properties

 Chemists have classified elements by their chemical properties and arranged them
in the Periodic Table in groups (columns) of elements with similar chemical properties due to them having the same number of outer electrons

Group 7 = halogens; very reactive gases with 7 outer electrons
  Group 8 (or 0) = Noble (or Inert) Gases - UNREACTIVE - full outer orbital.
   Group 1  = Alkali metals - reactive metals - one outer electron.

  Transition Metals - middle box of Periodic Table.

 Every element is made up of very small particles called atoms each with a different number of protons called the Atomic Number.
 Atoms of different elements vary in size and in mass.
Atomic structure lecture
 
 
    particle mass charge position in nucleus
  proton 1 +1 nucleus at centre
  neutron 1 neutral nucleus at centre
  electron- 0 -1 spinning around the nucleus

Equal numbers of positive protons and negative electrons make the atom neutral

   mass number = number of +ve protons = number of neutral neutrons
 
  mass number = 27
  Al = symbol
  atomic number=13

thus number of protons = 13
  number of neutrons= mass number - protons = 27-13 = 14
  number of electrons = 13 same as protos in neutral atom (or look it up in data book where electron arrangement is 2,8,3 which add together to be 13

or for Sulphur
  mass number = 32
  S = symbol for sulphur
  atomic number=16

thus number of protons = 16
  number of neutrons= mass number - protons = 32-16 = 16
  number of electrons = 16 same as protons in neutral atom (or look it up in data book where electron arrangement is 2,8,6 which add together to be 16)

Atomic and mass number demo

Formation of ions
The only atoms that do not react are those of the nobel gases.
Most atoms are unstable and react to become stable. This invloves the atom obtaining a structure which has a full outer orbital; whuich is usually 8

(i) For aluminium with an electron arrangement of 2,8,3 this would become 2.8.

thus for Aluminium number of protons = 13
  number of neutrons= mass number - protons = 27-13 = 14
  number of electrons = where electron arrangement is 2,8 which add together to be 10
 
  This means that there are 13 positive protons and 10 negative electrons giving an
  overall charge of +ve 3
  mass number = 27 +3 = charge
  Al
  atomic number=13

(i) For sulphur with an electron arrangement of 2,8,6 this would become 2.8,8

thus for sulpur number of protons = 16
  number of neutrons= mass number - protons = 32-16 = 16 number of electrons = where electron arrangement is 2,8,8 which add together to be 18
 
  This means that there are 16 positive protons and 18 negative electrons giving an
  overall charge of -ve 2
  mass number = 32 -2 = charge
  S
  atomic number=16

 Isotopes are atoms of the same "element/ atomic number/ number of protons" but
different "mass number/ number of neutrons"

isotopes of chlorine

  mass number = 35 37
  Cl and Cl
  atomic number=17 17

atomic number ie number of protons the same (or they would be different elements).

mass number different - subtraction shows 18 neutron and 20 neutrons so neutrons different.

Isotopes of an atom have different abundances which results in the calculation of an average mass for each element called the relative atomic mass - rarely a whole number as it is an average.

Timeline of atomic theory
History of atomic theory

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