Syllabus Edition

First teaching 2014

Last exams 2024

|

Elements, Compounds & Mixtures (DP IB Chemistry: SL)

Revision Note

Test yourself
Stewart

Author

Stewart

Last updated

Elements & Compounds

  • Elements are substances made from one kind of atom
  • Compounds are made from two or more elements chemically combined
  • Elements take part in chemical reactions in which new substances are made in processes that most often involve an energy change
  • In these reactions, atoms combine together in fixed ratios that will give them full outer shells of electrons, producing compounds
  • The properties of compounds can be quite different from the elements that form them

The properties of sodium chloride are quite different from sodium and chlorine

Mixtures

  • In a mixture, elements and compounds are interspersed with each other, but are not chemically combined
  • This means the components of a mixture retain the same characteristic properties as when they are in their pure form
  • So, for example, the gases nitrogen and oxygen when mixed in air, retain the same characteristic properties as they would have if they were separate
  • Substances will burn in air because the oxygen present in the air supports combustion

Mixtures at the molecular level

Homogeneous or heterogeneous

  • homogeneous mixture has uniform composition and properties throughout
  • heterogeneous mixture has non-uniform composition, so its properties are not the same throughout
  • It is often possible to see the separate components in a heterogeneous mixture, but not in a homogeneous mixture

Types of Mixtures

Separating Mixtures

  • The components retain their individual properties in a mixture and we can often separate them relatively easily. The technique we choose to achieve this will take advantage of a suitable difference in the physical properties of the components

Mixtures & Separation Techniques

You've read 0 of your 10 free revision notes

Unlock more, it's free!

Join the 100,000+ Students that ❤️ Save My Exams

the (exam) results speak for themselves:

Did this page help you?

Stewart

Author: Stewart

Expertise: Chemistry Lead

Stewart has been an enthusiastic GCSE, IGCSE, A Level and IB teacher for more than 30 years in the UK as well as overseas, and has also been an examiner for IB and A Level. As a long-standing Head of Science, Stewart brings a wealth of experience to creating Exam Questions and revision materials for Save My Exams. Stewart specialises in Chemistry, but has also taught Physics and Environmental Systems and Societies.