Chemistry IGCSE Edexcel

Chemistry IGCSE Edexcel

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  • Created on: 31-05-11 10:45
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(a) Atoms
All matter is made of tiny particles which constantly move around/vibrate. This
can be proven through the following experiments:
· Coloured solutions diffuse and become diluted
· Gases diffuse (prove by HCL fumes and ammonia forming white ammonium
· Brownian motion ­ smoke/dust particles in air/water get pushed around by
smaller air/gas particles, resulting in random movement.
· Atom ­ particles of which elements are composed of
· Molecules ­ is two or more atoms chemically bonded together
· Element ­ is a substance consisting of only one type of atom
· Compound ­ is a substance consisting of two or more types of atoms which are
chemically bonded together, in fixed proportions
· Mixture ­ is when two or more types of atoms are physically, but not chemically,
combined and will not be in fixed proportions
(b) Atomic structure
Atom consists of a nucleus (protons and neutrons) surrounded by orbiting electrons
Relative Mass Relative Charge
Proton 1 +1
Neutron 1 0
Electron 1/1837 -1
16 mass number ­ grams/mol : number of protons and neutrons
8 atomic number = number of protons = number of neutrons
Isotopes are atoms of the same elements which have same amount of protons and
electrons, but different amount of neutrons, thus a different mass number.

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Relative atomic mass (Ar) ­ is the average mass number of all the isotopes of an
element, weighted by the percentage, or relative abundance, of its isotope.
Electronic configuration ­ the arrangement of electrons in an atom
· First electron shell ­ 2 electrons
· Second/Third electron shell ­ 8 electrons
(c) Relative formula masses and molar volumes
Relative formula masses (Mr) ­ calculating the grams/mol of a compound
A mole of an substance = 6.…read more

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Li + Ca 2+ PO4
Na + Cu 2+ Al 3+
K+ O 2- Fe (III) 3+
H+ Mg 2+
Ag +
OH ­ Zn 2+
NO3 + Lead 2+
NH4+ Barium 2+
Iron (II) 2+
· use the dot and cross model to explain the formation of an ionic compound by
electron transfer, limited to combinations of Li+, Na+, Mg2+, F-, Cl- and O2-
· use dot and cross diagrams to represent single covalent bonds in
hydrogen chloride
nitrogen…read more

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Boiling/ Giant Ionic Simple Giant Giant Metallic:
melting Structures: Covalent: Covalent: High melting
points High melting points Lower melting High melting points because
because there are points because points because lots of energy is
strong although there many these required break
intermolecular are strong structures the electrostatic
forces of attraction intramolecular contain many forces of
throughout the ionic forces of atoms joined attraction
structure.…read more

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Uses lubricant cutting
Section C2: Chemistry of the elements
(a) The Periodic Table
Periodic Table ­ elements are arranged in order of atomic number
Periods: the rows on the table. Elements going across a period:
· Increase in number of electrons on outer energy level/shell
· Change gradually from metal to non-metal
· Giant metallic > giant covalent > simple molecular
Groups: the columns on the table.…read more

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More dense
· Lower boiling point
· Softer
Group 7: Halogens ­ seven electrons on outer shell, forms -1 anion when reacted
· Low boiling/melting point
· Exists as diatomic molecules
· Brittle when solid
· Non-metal
· Poor conductor of heat/electricity
· Coloured fumes
· Iodine used as antiseptic for wounds, chlorine for killing microorganisms in pool
· A more reactive halogen will displace a less reactive one from its compound
Trends in reactivity (as you go down the group):
· Less reactive (when…read more

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Group 0: Noble Gases
· Full outer shell
· Inert gases (very un-reactive)
· Single atom gases
· Low melting point
· Low density
· Colourless
Trends in reactivity (as you go down the group):
· Higher density
· Higher boiling/melting point
Helium Less dense than air, helium ballons
Neon Produce light when electricity passes
through (neon lights)
Argon Fill light bulbs as it is not reactive and
won't react with the filament
(d) A transition metal ­ copper
· Transition metals are harder than…read more

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Redox reaction ­ more reactive metal takes the oxygen from the less reactive
· Displacement reaction (of aqueous solutions)
recall the reactions with oxygen, water and dilute acids used to establish reactivity
Metal + Oxygen Metal Oxide
Metal + Water Metal Hydroxide + Hydrogen
Metal + Acid Salt + Hydrogen
Metal Oxide + Acid Salt + Water
Metal Hydroxide +Acid salt + water
Metal Carbonate + Acid Salt + water + Carbon dioxide
Rust ­ is when iron or steel becomes oxidized (lose electrons)…read more

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White precipitate of silver chloride
Test for metal ions (cations) (metal ions in compounds)
Lithium Li+ Flame Test for metal Red
Sodium Na+ cations Yellow
Potassium K+ Lilac
Calcium Ca+ Brick Red
Ammonium Sodium Hydroxide NH4+(aq) + NaOH NH3(g) + H20(l) +
ions (NH4 - ) Na+(aq)
The NH3 (ammonia gas) is tested as above
Copper 2+ Sodium hydroxide NaOH(aq) + Cu+ CuOH (s) + Na+
Blue precipitate (clear excess NaOH)
Ammonia Solution Blue precipitate (dark blue excess ­ the
NH3 + H2O NH4+ excess…read more

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They are "saturated" means that they only have single covalent bonds, so no
more atoms can be added
Homologous Series: a family of compounds which have similar structure and chemical
properties. A family of compounds can be represented by a general formula. Members
of the same homologous series may show a gradual trend in their physical properties.
General Formula: is the chemical formula used for compounds belonging to the same
homologous series.…read more


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