Unit 1 Measurement & Matter

1. Unit 1 Measurement & Matter Ms. Randall Regents Chemistry

2. Lesson 2: Matter

3. In the past…. Early Chemists describe the first DIRT MOLECULE. (from the Far Side)

7. What is Matter? • Matter is anything that has volume and mass. • Mass is the amount of matter in an object. • Volume is the amount of space an object occupies.

8. Matter is classified as a pure substance or as a mixture of substances.

9. Elements are substances that are composed of atoms that have the same atomic number. Elements cannot be broken down by chemical change. There are more than 100 different elements Elements are represented by chemical symbols The first letter of the symbol is always a capital letter the rest are lower case Nitrogen Neon A temporary symbol

10. Some elements are diatomic. They come in pairs when not combined with other elements. • Diatomic Elements • Hydrogen • Oxygen • Nitrogen • Chlorine • Bromine • Iodine • Fluorine H O N Cl Br I F Neon is a monatomic element Ne Nitrogen is a diatomic element N2

11. Compounds are substances that are composed of two or more different elements chemically combined. • The elements in a compound are in fixed proportions • A compound can only be decomposed by chemical means • Compounds are represented by chemical formulas • Compounds are electrically neutral

12. Mixtures are composed of two or more different substances that can be separated by physical means.

13. When different substances are mixed together, a homogeneous or heterogeneous mixture is formed. A homogeneous mixture is called a solution A solution in which something is dissolved in water is called an aqueous solution NaCl (aq) means that sodium chloride (table salt) is dissolved in water and is therefore a homogenous mixture. (aq) stands for aqueous An alloy is a mixture of metals eg. brass, bronze

14. The proportions of components in a mixture can be varied. Each component in a mixture retains its original properties. Two mixtures of Hydrogen (H2) and Neon (Ne)

15. Check your understanding and practice

16. Lesson 4: Particle Diagrams

17. Particle diagrams represent elements, compounds and mixtures. Element Compound Diatomic element Mixture

21. Check your understanding and practice

22. Lesson 5: Methods of Separating a Mixture

23. Lesson 15: Methods of Separating a Mixture

24. Physical separation of a mixture Mixtures are made by physicallycombining 2 or more pure substances together; we use physicaltechniques to separate them.

25. Separation of Matter

26. Separate solute (dissolved solid) from solvent (liquid) by boiling solution • Solvent escapes • Very limited precision

29. On the other hand  Chemical Separation requires reacting a sample with something else in order to turn it into a completely different compound

30. Check your understanding and practice

31. Lesson 6: Properties and Changes of Matter

32. Properties of Matter Physical Properties- can be observed and measured without changing the substance. • Example: melting point, color, texture Chemical Properties- can only be observed by changing the type of substance. • Examples: reacting hydrogen with oxygen gas results in a combustion reaction, very reactive when in the presence of nonmetals, pH

33. Physical Changes Vs Chemical Changes • Matter is always changing. Ice in your drink melts. Wood in your fire burns. Glass breaks.

34. Physical Change – a change that does NOT alter the chemical properties of a substance (example: cutting paper, phase change); change in size or shape; same material, but different form; looks different butcan go back to original state; no energy produced as a product

35. Chemical Change – a reaction in which the composition of a substance is changed (example: rusting); properties not the same as the original matter; energy is produced (in the form of light, fire, heat etc)

36. Check your understanding and practice

37. Chemical Reactions • Another name for chemical change • When one or more substances are changed into new substances. • Reactants- stuff you start with • Products- What you make • NEW PROPERTIES • Because each substance has its own properties

38. Indications of a chemical reaction • Energy absorbed or released • Color change • Odor change • Precipitate-solid that separates from solution • Not easily reversed • Only clues not certainty

39. Check your understanding and practice

40. Lesson 7: STP and States of Matter

41. States of Matter

43. How can we compare matter? “Under the same conditions!” Table A

44. We can use Table S to determine the State of an element at Room Temperature or at “Standard” Temperature .

45. Check your understanding and practice

46. Lesson 8: Changes Written as Equations

47. Chemical formulas are used in chemical equations to describe matter. Asubscript in a formula tells how many atoms of each kind are in a molecule. Examples: H2O 2 H’s and 1 O in each molecule C2H6 2 H’s and 6H’s in each molecule Na2SO4 2 Na, 1 S and 4 O in each molecule

48. A number before the formula is called a coefficient. This number tells how many molecules we are dealing with or describing. Examples: 2H2O is 2 molecules of the compound H2O 5H2O is 5 molecules of H2O 1Na is 1 atom of the element Na 3Na is 3 atoms of Na

49. An equationdescribes a chemical change or reaction. The equation shows substances which react with each other once mixed to form other substances. Reactants (the substances that we start with, or in other words that react) are on the left side of the equation. Products (thesubstances that we end with, or in other words are produced) are on the right side of the equation. Reactants and products are separated by an arrow. It shows the direction of the equation. System is another word for reaction that is often used by chemists.

50. Conservation of Mass • Mass can not be created or destroyed in ordinary (not nuclear) changes. • All the mass can be accounted for. • Mass at the start = mass at end