IB Chemistry S1.1 Notes

To begin chemistry, it is important to understand that matter can appear as three types of substances: elements, compounds, and mixtures.

1. Elements are the simplest substances made of atoms that cannot be broken down.
2. Compounds are substances made up of two or more atoms chemically bonded in fixed ratios and have different properties than their components.
3. Mixtures are substances made up of more than one element or compound not chemically bonded together so that they retain their individual properties. There are two different types of mixtures:
   1. Homogeneous – the components of the mixture are uniformly distributed. They thus cannot be distinguished from one another. This often occurs when two components are in the same state (such as water & alcohol), but this may not always be the case (such as water & oil).
   2. Heterogeneous – the components of mixture are not uniformly distributed. They thus can be distinguished from one another. This often occurs when two components are in different states (such as water & sand), but again, this may not always be the case (such as water & sugar).