Properties of Matter

1. Properties of Matter 2.1 Classifying Matter

2. Section 2.1: Classifying Matter • Scientists like to classify things. • One way that scientists classify matter is by its composition. • Ultimately, all matter can be classified as mixtures, elements and compounds.

3. Section 2.1: Classifying Matter • Pure Substances • What is Matter? Anything that has mass and takes up space (volume) • Based on matter’s composition, it can be divided into Pure Substances and Mixtures.

4. MIXTURE PURE SUBSTANCE yes no yes no Is the composition uniform? Can it be decomposed by chemical means? Matter Flowchart MATTER yes no Can it be separated by physical means? Homogeneous Mixture (solution) Heterogeneous Mixture Compound Element

5. Section 2.1: Classifying Matter • Pure Substances • Def.-matter that always has exactly the same composition (ex. Table salt, table sugar) • Key Concept: Every sample of a given substance has the same properties because a substance has a fixed, uniform composition. • 2 Categories of substances: elements and compounds

6. Section 2.1: Classifying Matter • Elements • Def.-a substance that cannot be broken down into simpler substances • Key Concept: An element has a fixed composition because it contains only one type of atom.

7. Section 2.1: Classifying Matter • Elements: Examples of Elements • Carbon (C), Aluminum (Al)- solid at RT • Oxygen (O), Nitrogen (N)- gases at RT • Bromine (Br), Mercury (Hg)- liquid at RT

8. Section 2.1: Classifying Matter • Elements: Symbols for Elements • Developed in 1813 by Swedish chemist Jons Berzelius • Symbols contain 1 or 2 letters • Symbols based on Latin names of the elements • Gold is Au • Aluminum is Al

9. Section 2.1: Classifying Matter • Compounds • Def.-a substance that is made from two or more simpler substances and can be broken down into those simpler substances (elements or other compounds) • H2O→2H + O

10. Section 2.1: Classifying Matter • Compounds • Properties of a compound differ from the properties of the substances from which it is made. • Ex. H and O are gases at room temp.; H2O is liquid at room temp.

11. Section 2.1: Classifying Matter • Compounds • Key Concept: A compound always contains two or more elements joined in a fixed proportion. • Ex. SiO2- 2 (O) atoms for every 1 (Si) atom • Ex. H2O-2 (H) atoms for every 1 (O) atom

12. Section 2.1: Classifying Matter • Mixtures • 2 types: heterogeneous and homogeneous • Retain some of the properties of their individual substances • Properties of a mixture are less constant (vary) than the properties of a substance.

13. Section 2.1: Classifying Matter • Mixtures • Key Concept: The properties of a mixture can vary because the composition of a mixture is not fixed. • **Mixtures can be classified by how well the parts of the mixture are distributed throughout the mixture.

14. Section 2.1 Classifying Matter • Mixtures: Heterogeneous and Homogeneous Mixtures • Heterogeneous- the parts of the mixture are noticeably different from one another • Ex. Sand • Homogeneous-the substances are so evenly distributed that it is difficult to distinguish one substance in the mixture from another • Ex. Water, steel

15. Section 2.1 Classifying Matter • Is the mixture uniform throughout? • If the answer is NO, the matter is a heterogeneous mixture. • Considered the “least mixed.” • Does not appear to be the same throughout. • Particles are large enough to be seen and to be separated from the mixture.

16. Section 2.1 Classifying Matter • Is the mixture uniform throughout? • If the answer is YES, the matter is a Homogenous mixture.

17. MIXTURE PURE SUBSTANCE yes no yes no Is the composition uniform? Can it be decomposed by chemical means? Matter Flowchart MATTER yes no Can it be separated by physical means? Homogeneous Mixture (solution) Heterogeneous Mixture Compound Element

18. Section 2.1 Classifying Matter • Solutions, Suspensions, and Colloids • The size of the particles in a mixture has an effect on the properties of the mixture. • Key Concept: Based on the size of its largest particles, a mixture can be classified as asolution, a suspension, or a colloid.

19. Section 2.1 Classifying Matter • Solutions • Def.-the mixture that forms when substances dissolve and form ahomogeneous mixture • Ex. Sugar water, salt water, lemonade

20. Section 2.1 Classifying Matter • Solutions • *They do not separate into distinct layers over time. • *They cannot be filtered. • *Light passes through them. • The particles in a solution are too small to settle out of the solution, be trapped by a filter, or scatter light.

21. Section 2.1 Classifying Matter • Suspensions • Def.-a heterogeneous mixture that separates into layers over time • Ex. Amoxicillin, Muddy water, Flour suspended in water

22. Section 2.1 Classifying Matter • Suspensions • *Suspended particles settle out of a mixture or are trapped by a filter • They scatter light in all directions because the particles are large; suspensions are cloudy.

23. Section 2.1: Classifying Matter • Colloids • Def.-a mixture that contains some particles that are intermediate in size between the small particles in solution and larger particles in a suspension • Ex. Milk, fog

24. Section 2.1 Classifying Matter • Colloids • Do not separate into layers • Cannot be filtered • Since they also contain larger particles, they scatter light

25. MIXTURE PURE SUBSTANCE yes no yes no Is the composition uniform? Can it be decomposed by chemical means? Matter Flowchart MATTER yes no Can it be separated by physical means? Homogeneous Mixture (solution) Heterogeneous Mixture Compound Element