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Intermolecular forces
David Fowkes
Chemistry A Level
Intermolecular forces are responsible for holding together the two strands of a DNA molecule Before tackling this topic make sure you are able to: explain the difference between intermolecular and intramolecular forces. use electronegativity values to work out dipoles within moleculesuse ideas about molecular shapes and dipoles to predict whether or not a molecule is polar.  Hydrogen bonds in DNA&nbs...
Three questions:
David Fowkes
Chemistry A Level
water expands when it freezes and ice therefore floats 1. Why is water a liquid and not a gas ( between 0 and 100oC) ? Water has a Relative Molecular mass ( Mr) of 18 ... Oxygen's Mr is 32. If Mr was the only factor that affects the state of a substance then wouldn't you expect water to be a gas ? 2. Why does Ice float on water? Most liquids become more dense as they cool. This caus...
Energetics old
David Fowkes
IGCSE Chemistry
An Exothermic reaction. Acetylene (Ethyne) releases a lot of energy when it burns. Enter your text here ... Introduction ​Every chemical reaction has an accompanying change in energy. Some reactions release energy to the surroundings and are known as Exothermic. Reactions which take in energy from their surroundings are known as Endothermic  Enter your text here ... ​This shows a range of chemical changes - all of which rele...
1.14 - 1.17 Atomic structure
David Fowkes
IGCSE Chemistry
If a nucleus was the size of a raisin, the rest of the atom would be the size of a sports stadium
Atomic structure
David Fowkes
Principles of chemistry
If a nucleus was the size of a raisin, the rest of the atom would be the size of a sports stadium  Atomic models Atoms are the building blocks of matter. Atoms are the smallest possible particles into which an element can be subdivided, without changing its properties.  As building blocks, they can be thought of spheres.  However, to understand how and why atoms join up with one another, a more sophisticated model is needed....
1.17 Relative atomic mass
David Fowkes
Uncategorized
The mass spectrum of boron  1.17 Activity 2. Calculating relative atomic mass.  Students should: 1.17 be able to calculate the relative atomic mass of an element (Ar) from isotopicabundances.  Sorting by mass A mass spectrometer is an instrument which can separate and sort the particles in a sample of an element according to their mass. The output from a ...
1.16 Isotopes
David Fowkes
IGCSE Chemistry
 1.16 Activity 1. Three types of carbon atom  Students should: 1.16 know what is meant by the terms atomic number, mass number, isotopes and relative atomic mass (Ar). Use this animation to explore the number and type of sub atomic particles which make up the three isotopes of carbon. Use the information to complete a copy of th...
1.15 Subatomic particles
David Fowkes
IGCSE Chemistry
masses and charges of subatomic particles  1.15 Sub atomic particles  Students should: 1.15 know the structure of an atom in terms of the positions, relative masses and relativecharges of sub-atomic particles. Here we look at the particles inside the atom. Sub atomic particles are the particles found inside atoms. These include protons, neutrons and electrons: protons a...
1.14 Atoms and molecules
David Fowkes
IGCSE Chemistry
If a nucleus was the size of a raisin, the rest of the atom would be the size of a sports stadium
Your carbon footprint
David Fowkes
IGCSE Chemistry
reducing your carbon footprint Although this is aimed at students of the IB diploma - it is relevant to all .... Enter your text here ...

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