IGCSE Chemistry

IGCSE Chemistry

By Karen Lewis

 Names of compounds:

For compounds consisting of 2 atoms:

• If one is a metal and the other a nonmetal, then the name of the metal atom comes first and the ending of the second atom is replaced by adding -ide

  • Eg. NaCl which contains sodium and chlorine thus becomes sodium chloride

Some text here about the topic of discussion

• If both atoms are nonmetals and one of those is hydrogen, then hydrogen comes first

  • Eg. hydrogen and chlorine combined is called hydrogen chloride

Subject | Subject

Some text here about the topic of discussion

For other combinations of nonmetals as a general rule, the element that has a lower Group number comes first in the name

​

• Eg. carbon and oxygen combine to form CO₂ which is carbon dioxide since carbon is in Group 4 and oxygen in Group 6

Some text here about the topic of discussion

 For compounds that contain certain groups of atoms:

​There are common groups of atoms which occur regularly in chemistry:

• Examples include the carbonate ion(CO₃^2-), sulfate ion (SO₄^2-), hydroxide ion (OH^-) and the nitrate ion (NO₃^-)

• When these ions form a compound with a metal atom, the name of the metal comes first

• Eg. KOH is potassium hydroxide, CaCO₃ is calcium carbonate

Some text here about the topic of discussion

Multiple Choice

What is the formula of the molecule

• C2H6O

• C2H4O2

• C4H8O2

• C2H2O2

Multiple Choice

Theobromine is a stimulant found in chocolate and tea leaves and is closely related to caffeine. What is the formula of Theobromine?

• C6H5N402

• C7H8N402

• C7H8N402

• C7H7N402

Multiple Choice

What is the correct equation for this reaction?

• 2H + 2F >> 2HF

• H2 + F2 >> H2F2

• 2H + 2F >> H2F2

• H2 + F2 >> 2HF

ReplaChemical formulaece this with a header

​Replace with sub-header

Replace this with your body text. Duplicate this text as many times as you would like. All provided templates can be reused multiple times. Wish you a good day.

Happy teaching!

Some text here about the topic of discussion

• The structural formula tells you the way in which the atoms in a particular molecule are bonded. This can be done by either a diagram (displayed formula) or written (simplified structural formula)

• The empirical formula tells you the simplest whole-number ratio of atoms in a compound

• The molecular formula tells you the actual number of atoms of each element in one molecule of the compound or element e.g. H₂ has 2 hydrogen atoms, HCl has 1 hydrogen atom and 1 chlorine atom

Chemical formulae

​Valency

​

• The concept of valency is used to wok out the formulae of compounds

• Valency or combing power tells you how many bonds an atom can make with another atom

• Eg. carbon is in Group IV so a single carbon atom can make 4 single bonds or 2 double bonds

Subject | Subject

Some text here about the topic of discussion

• We can use the combining power of each atom to work out a formula

• Example: what is the formula of aluminium sulfide?

  • Write out the symbols of each element and write their combining powers underneath:

  • Al         S

    3          2

• The formula is then calculated by cross multiplying each atom with the number opposite, hence the formula for aluminium sulfide is Al₂S₃

​Deducing Formulae of Ionic Compounds:

The formulae of these compounds can be calculated if you know the charge on the ions.

Balance the charges by multiplying them out:

​

​

Al³⁺ x 2 = +6

SO₄^2- x 3 = -6

so,

+6 - 6 = 0

​

• So the formula is Al₂(SO₄)₃

​

​

​

• For ionic compounds you have to balance the charge of each part by multiplying each ion until the sum of the charges = 0

• Example: what is the formula of aluminium sulphate?

  • Write out the formulae of each ion, including their charges

  • Al³⁺ SO₄^2-

Multiple Choice

A compound contains 2 atoms of oxygen and one atom of Calcium. It also contains Hydrogen in sufficient amounts that the overall charge of the molecule is neutral.

What is the molecular formula of the Compound?

• Ca(OH)4

• Ca(OH)2

• H4CaO2

• CaO2H2

Multiple Choice

Which was the balanced equation from the previous slide?

• A

• B

• C

• D

Multiple Choice

6g of Hydrogen reacts with 48g of Oxygen to form water. You perform the same experiment using 23g of Hydrogen. How much Oxygen did you use?

• 24g

• 12g

• 16g

• 18g

Multiple Choice

Which is not correct

• Li2S

• Fe2F3

• Al2(SO4)3

• Mg(NO3)2

Multiple Choice

3CuO = 2NH3>>

What are the products of this equation?

• 3Cu +2N + 3H2O

• 3Cu + 3HNO3

• 3Cu + N2 + H20

• 3Cu + N2 + 3H20