What is Chemistry?

1. What is Chemistry?

2. Chemistry – the study of the composition of matter and the changes that matter undergoes • Matter – the ‘stuff’ that things are made of • Everything is made of matter • Examples of things containing matter:

3. Divisions of Chemistry • Practical – applications to everyday life • Example: teflon, computer chips • Theoretical – Does not apply to everyday life (at least not yet) • Example: force fields, light speed travel

4. Divisions of Chemistry • 5 major areas of study: • Organic – study of carbon containing substances • Inorganic – substances without carbon • Analytical – composition of substances • Physical – behavior of chemicals • Biochemistry – chemistry of living organisms • These areas overlap

5. Why Study Chemistry? • Come up with an aspect of life that does not involve chemistry:

6. How do these pictures relate to chemistry?

7. The Scientific Method • A logical approach to the solution of scientific problems • Closely related to common sense: • Example: When you turn on a flashlight and it does not light – you made an observation • You guess that the batteries are dead – this is a hypothesis • You put new batteries in the flashlight – experiment

8. The Scientific Method • Observation – Observe something about the world around you • Hypothesis – propose an explanation for what you observed • Experiment – Test your hypothesis with a controlled experiment • Collect and Analyze data – look for a correlation between data and hypothesis • Theory – accepted explanation of why the experiment gave the results it did

9. Scientific Law • Statement summarizing results of many observations and experiments • Describes a natural phenomenon without attempting to explain it. • Example: Law of Gravity: no accepted explanation exists, we just know it happens

10. How is a scientific theory different than a scientific law? Do scientists always follow the scientific method? Give an example of when a scientist cannot use the scientific method:

11. Matter Matter is anything that occupies space and has mass. Mass – tha amount of matter in an object (measured in grams) Volume – the amount of space an object occupies (mL or L or cm3) Weight – the amount of pull of gravity on an object (measured in Newtons)

12. States of Matter Solid (s) 1. Definite shape and definite volume 2. Particles stick rigidly together and vibrate – they don’t move position 3. Often crystalline structure – fixed, repeating internal structure 4. Amorphous solids – do NOT have a crystalline structure 5. Melting point – temperature at which a solid turns into a liquid (solid and liquid are in equilibrium 6. Sublimation – change from a solid to a gas ( skips the liquid stage

13. States of Matter Liquid (l) 1. No definite shape but has definite volume 2. Particles stick together but NOT rigidly and do NOT have a pattern. (more random) 3. Evaporation – when liquid changes into a gas 4. Vapor pressure – in closed containers some liquid changes to a gas which exerts pressure on the container walls a. Table H in reference tables.

14. States of Matter 5. Boiling Point – when vapor pressure equals atmospheric pressure A. the atmospheric exerts a pressure on everything B. at the boiling point of water the vapor pressure is 101.3Kpa,(1atm.) and is equal to the atmospheric pressure

15. States of Matter Gas (g) 1. No fixed volume and no definite shape 2. Gas pressure is caused by particles move and collide with the walls of a container 3. Particles are far apart and move in all directions 4. Can be compressed or expanded Aqueous (aq) Something dissolved in water, example NaCl(aq)

16. States of Matter Plasma 1. Composed of electrically charged atomic particles 2. Examples: Stars including the our Sun 3. Made by heating gas to extremely high temperatures or or by passing a current though it

17. States of Matter Entropy 1. As matter goes from a solid to a liquid and then a gas the entropy increases Note: Entropy is the randomness of a particle's energy and position

18. Physical Properties Properties - characteristics that identify an object: Physical properties: observed and measured without changing to something else Ex: State, Color, solubility and melting point Physical Change: Alters 1 or more physical properties without changing the chemical composition

19. Chemical Properties Chemical Properties: formed when a substance reacts with another substance to form a different chemical composition Chemical Changes: cannot be observed without altering the chemical composition Ex: Na + Cl NaCl (Sodium Metal) + (Chlorine gas ) produces(Table Salt) Poisonous

20. Elements The basic building blocks of matter: Elements are pure substance that can NOT be broken into simpler substances. Found on the Periodic Table. Ex: C, N, O… Each element has their own unique physical and chemical properties

21. Compounds Compounds can be broken down into single elements by chemical changes Ex: H20 into 2 Hydrogens and 1 Oxygen NaCl into Sodium and Chlorine Binary compounds have only two elements. Ternary – compounds that have 2+ elements Diatomic compounds have only two elements that are the same. Diatomic elements include – H, N, O, F, Cl, Br and I

22. Pure Substances and Mixtures Pure substances • Matter with fixed composition (can be elements or compounds) • Cannot be separated into any other form of matter by physical change (for compounds) Ex: He is an element (look on the Periodic Table) O2 (g) is a diatomic gas, Oxygen NaCl is table salt

23. Pure Substances and Mixtures Mixtures 1. Combined 2 or more pure substances Ex: salt and sugar 2. Composition can vary 3. Can separate by physical means 4. Can be heterogeneous OR homogeneous

24. Classification of Matter Homogenous matter • Same parts with same properties throughout Ex: Teaspoon of sugar, any element

25. Classification of Matter Homogeneous mixture 1. Uniform blend of 2 or more substances 2. Can vary in proportion (like concentration) 3. Every part is exactly like every other part (think Kool-Aid) Ex: salt dissolved in water (a solution)

26. Classification of Matter Heterogeneous matter 1. Different parts with different properties Ex: Salt and Pepper

27. Classification of Matter Heterogeneous mixture 1. Different parts with different properties 2. Made of 2 or more substances with each retaining their unique properties (boiling point, solubility, etc.) 3. NOT the same composition or properties throughout 4. Composition can vary 5. Does NOT make a solution Ex: Salt and sand

28. Separating Mixtures • With a magnet 1. Mixture of iron and sulfur 2. Separated by their physical properties • Distillation 1. Process in which a mixture can be separated by its boiling points 2. Ex: Petroleum (mixture of gas, kerosene and oil) when it boils the liquids separate with gas boiling first

29. Separating Mixtures C. Filtration 1. Process that separates the solid and liquid parts 2. Use filter paper, funnel – the liquid part goes through the filter a. If solid is dissolved in liquid it will also go through paper Ex: Soda has carbon dioxide gas

30. Separating Mixtures D. Chromatography 1. Way to separate different molecules in a mixture 2. Put drop from mixture near one end of chromatography paper – then put paper into the solvent and the mixture will move up so that molecules move different distances http://www.wooster.edu/chemistry/analytical/gc/default.html