Edexcel IGCSE Chemistry
notes:
Topic 1 – States of Matter
SOLID: LIQUID: GAS:
Propertie Difficult to Difficult to Easily
s: compress compress compressible
Has its own shape Takes shape of No fixed shape
container
Moveme Vibrating around Free flowing (slowly) Moves randomly
nt: fixed position
Energy: LOW MORE energy HIGH
Diagram:
Topic 2 – Elements, Compounds and
Mixtures
Atom – the smallest unit of matter that forms a chemical element
Element – a substance containing only 1 type of atom
Compound – a substance containing 2 or more elements, chemically
combined
Mixture – 2 or more substances that are physically combined
Methods for Separating mixtures:
1. Filtration:
Separates an insoluble solid from a liquid
, e.g., water from a mixture of sand and
water
2. Evaporation:
Obtain a soluble solid from a liquid
e.g., salt from water
3. Simple Distillation:
Separate the solvent from a solution
e.g., ethanol from water
4. Fractional Distillation:
Separates mixtures of miscible
liquids with different boiling
points
e.g., fractional distillation of
crude oil
, Topic 3 – Atomic Structure
Structure of the Atom:
Proton – charge +1, mass 1
Neutron – charge 0, mass 1
Electron – charge -1, mass 1/1840
Nucleus – contains protons and neutrons (most of the mass)
Electrons – arranged in shells around the nucleus
Atoms are neutral – same number of protons and electrons; mostly empty
space
Atomic and Mass Numbers:
Atomic number (Z) – number of protons in the nucleus
Mass number (A) – total number of protons and neutrons
Isotopes – atoms of the same element with the same number of protons
but different numbers of neutrons; same chemical properties (same
electron arrangement) but different physical properties (different masses)
E.g., Carbon-12 and Carbon-14 are isotopes of carbon
Relative Atomic Mass (Ar):
Weighted average of the masses of the isotopes of an element (compared
with mass of carbon-12 atom)
R.A.M = (mass₁ × abundance₁ + mass₂ × abundance₂) ÷ 100
Electronic configurations and the periodic table:
Electronic configuration – way in which an atom’s electrons are
arranged
Rules (for first 20 elements):
1. 1st shell holds up to 2 electrons
2. 2nd and 3rd shell holds up to 8 electrons each
3. Electrons fill shells from the innermost, outwards
E.g., Sodium (Na): 11 electrons → 2,8,1 = 2e- in shell 1, 8e- in shell 2, 1e-
in shell 3
– Group number = number of electrons in outer shell
– Period number = number of shells
Ions:
Formed when atoms lose or gain electrons to achieve a full outer shell
Metal atoms lose electrons → form positive ions (cations)
Non-metal atoms gain electrons → form negative ions (anions)
Topic 4 – Bonding
notes:
Topic 1 – States of Matter
SOLID: LIQUID: GAS:
Propertie Difficult to Difficult to Easily
s: compress compress compressible
Has its own shape Takes shape of No fixed shape
container
Moveme Vibrating around Free flowing (slowly) Moves randomly
nt: fixed position
Energy: LOW MORE energy HIGH
Diagram:
Topic 2 – Elements, Compounds and
Mixtures
Atom – the smallest unit of matter that forms a chemical element
Element – a substance containing only 1 type of atom
Compound – a substance containing 2 or more elements, chemically
combined
Mixture – 2 or more substances that are physically combined
Methods for Separating mixtures:
1. Filtration:
Separates an insoluble solid from a liquid
, e.g., water from a mixture of sand and
water
2. Evaporation:
Obtain a soluble solid from a liquid
e.g., salt from water
3. Simple Distillation:
Separate the solvent from a solution
e.g., ethanol from water
4. Fractional Distillation:
Separates mixtures of miscible
liquids with different boiling
points
e.g., fractional distillation of
crude oil
, Topic 3 – Atomic Structure
Structure of the Atom:
Proton – charge +1, mass 1
Neutron – charge 0, mass 1
Electron – charge -1, mass 1/1840
Nucleus – contains protons and neutrons (most of the mass)
Electrons – arranged in shells around the nucleus
Atoms are neutral – same number of protons and electrons; mostly empty
space
Atomic and Mass Numbers:
Atomic number (Z) – number of protons in the nucleus
Mass number (A) – total number of protons and neutrons
Isotopes – atoms of the same element with the same number of protons
but different numbers of neutrons; same chemical properties (same
electron arrangement) but different physical properties (different masses)
E.g., Carbon-12 and Carbon-14 are isotopes of carbon
Relative Atomic Mass (Ar):
Weighted average of the masses of the isotopes of an element (compared
with mass of carbon-12 atom)
R.A.M = (mass₁ × abundance₁ + mass₂ × abundance₂) ÷ 100
Electronic configurations and the periodic table:
Electronic configuration – way in which an atom’s electrons are
arranged
Rules (for first 20 elements):
1. 1st shell holds up to 2 electrons
2. 2nd and 3rd shell holds up to 8 electrons each
3. Electrons fill shells from the innermost, outwards
E.g., Sodium (Na): 11 electrons → 2,8,1 = 2e- in shell 1, 8e- in shell 2, 1e-
in shell 3
– Group number = number of electrons in outer shell
– Period number = number of shells
Ions:
Formed when atoms lose or gain electrons to achieve a full outer shell
Metal atoms lose electrons → form positive ions (cations)
Non-metal atoms gain electrons → form negative ions (anions)
Topic 4 – Bonding
