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Formulae - Coggle Diagram
Formulae
Important prefixes
Penta- 5
Hexa- 6
Tetra- 4
Hepta- 7
Tri-3
Octa- 8
Di- 2
Nona- 9
Mono- 1
Deca- 10
Key information:ions
Group 4 metals do not tend to form ions, as they would have to lose or gain 4 electrons, and that takes up too much energy
Group 5 non-metals need to gain 3 electrons to have a full outer shell. They form ions with a 3- charge e.g P 3- and N 3-
Group 3 metals need to lose 3 electron to have a full outer shell. they form ions with a 3+ charge, e.g. Al 3+ an Ga 3+
Group 6 non-metals need to gain 2 electrons to have a full outer shell. They form ions with a 2- charge e.g O 2- and S 2-
Group 2 metals need to lose 2 electrons to have a full outer shell. they form ions with a 2+ charge, e.g. Mg 2+ and Ca 2+
Group 7 non-metals need to gain 1 electron to have a full outer shell. They form ions with a 1- charge e.g F- and Cl-
Group 1 metals(and hydrogen) need to lose 1 electron to have a full outer shell. they form ions with a 1+ charge, e.g. Na+ and Li+
Group 8 non-metals do not tend to form ions: they already have a full outer shell of electrons, sop are stable
COMPOUND IONS TO REMEMBER
Nitrate NO₃ (1-)
Ammonium NH₄ (1+)
Carbonate CO₃ (2-)
Hydroxide OH (1-)
Sulphate SO₄ (2-)
Writing chemical equations
Count how many atoms of each element are on each side
remember that some formulae are 'known' - e.g. the diatomic molecules (H, N, O, F, Br , Cl, I) - (I Have No Bright or Clever Friends), water (H₂O), ammonia (NH₃), methane (CH₄)
2.Work out the formulae involved either using prefixes (for molecules) or valencies (for ionic compounds)
start off by writing out the word equation.
Use 'big numbers' to balance any atoms if they are not the same
Atom, molecule or compound?
F- atom - it is a single atom, not joined to anything else
F₂- Molecule - 2 x non- metal atoms chemically joined(not a compound as not two different elements)
F₂O - Compound and a molecule-
compound as 2 x different elements joined together
molecule as 2 x non- metal atoms chemically joined
KF- compound- 2 x different elements joined together (not a molecule as K is a metal)
atom , ion, valency
Noble gases
have a full outer shell
The shells are COMPLETELY full
this makes them very stable (unreactive)
When combining with another element (forming a bond) atoms try to achieve a FULL OUTER SHELL like the noble gases
They achieve a full outer shell by gaining, losing, or sharing electrons
Molecules are formed when two or more non-metal atoms are chemically joined, in a fixed ratio
The atoms can be from the same element , or different elements
E.g a H₂O Molecule- (also a compound as two different elements chemically joines
E.g. an O₂ molecule (not a compound as the two atoms are from the same element
Brackets are used when you need MORE THAN ONE of the following in your formula: Nitrate, Ammonium, Carbonate, Hydroxide and sulphate