Structure 1.1—Introduction to the particulate nature of matter

What are elements made of?

atoms that all have the same number of protons

Key properties of elements:

1. made of one type of atomhave distinct physical and chemical properties.

2. represented by chemical symbols (e.g., H for hydrogen)

3. cannot be broken down into simpler substances.

Element

the simplest form of matter that cannot be broken down into simpler substances

Compound

a substance formed when two or more elements chemically bond together in fixed proportions

Difference between compounds and mixtures

In compounds, elements are chemically bonded to create a new substance. In mixtures, substances are only physically mixed.

Key properties of compounds:

1. have a fixed formula (e.g., H2O)

2. their properties ‍differ from the elements they are made of

3. can only be separated into their elements through chemical reactions

Mixture

two or more substances mixed together physically but not chemically bonded

What are the two types of mixtures?

homogenous- uniform composition throughout (saltwater, air)

heterogenous- non-uniform composition (oil and water)

Key properties of mixtures

1. components are not chemically bonded

1. they can be separated by physical methods (e.g., filtration, distillation).

2. the composition can vary (e.g., different concentrations of sugar in tea).

Pure substance

consists of only one type of particle with a fixed composition and uniform properties throughout.

What are the separation techniques of separating compounds of mixtures?

1. filtration

2. recrystalization

3. evaporation

4. distilation

5. paper chromatochraphy