Unit 2 Review: Chemistry

1. Unit 2 Review: Chemistry

2. Matter that has Chemical and Physical Properties

3. Key Concepts • • Particle theory of matter • • States of matter • • Classifying matter • • Observing physical properties • • Observing chemical properties • • Usefulness and impact of substances’ properties

4. Matter has many forms • Matter – anything that has mass and volume. • Mass is a measure of the quantity of an object. (g, kg,) • Volume is a measure of space taken up (mL, L) • Matter can be found as a solid, liquid or gas. (or even a combination of these)

5. Changes of State • There are 3 states of matter • Solid • Liquid • gas

6. Terms for changes of state

7. The Particle Theory of Matter (4 points) • Way of describing matter. • All matter is composed of very tiny objects called particles. • Each Pure substance has its own kind of particles, different from the particles of other pure substances.

8. The Particle Theory of Matter (4 points) 3. Particles present in matter are always in motion. Theymay be vibrating back and forth, as in a solid, or moving inall directions, as in a gas. In a liquid, particles stay closetogether but can slide past one another. 4. The particles in a substance attract each other. Theamount of attraction is different for different kinds ofparticles. All particles have spaces between them.

9. The Particle Theory of Matter (4 points) • The distancesbetween the particles change for different states of matter.

10. Classification Of Matter

11. Pure Substances (2) A pure substance is made up of only one kind of matter • unique set of properties • colour, hardness, boiling point, and melting point. • A pure substance is either an element (gold) or a compound (sugar).

12. Element A pure substance that cannotbe broken down into any simplersubstance by chemical means. • Each element has its own name and symbol. Example: Gold (Au)

13. Compound • A pure substance that is made from two or more elements that are combined together chemically. • Example, water (H2O) is a compound containing the elements hydrogen and oxygen.

14. Mixtures (3) • A mixture is a combination of pure substances. • Each substance remains in its original, pure form, although each is not always easy to see distinctly once the mixture is made.

15. Mechanical Mixture (heterogeneous mixture) • Different substances that make up the mixture are visible • Hetero = different

16. Suspension • A cloudy mixture in which tiny particles of one substance are held within another. • Can be separated out when the mixture is poured through filter paper. • A suspension is also a heterogeneous mixture.

17. Solution (homogeneous mixture) • Different substances that make it up are not individually visible • One substance is dissolved in another • The prefix “homo-” means same, and all parts of a homogeneous mixture look the same.

18. Physical Properties • -A physical property describes a characteristic of a substance that can be observed or measured without changing the composition of matter. • Example: Melting Point, Boiling Point

19. Observing Physical Properties

20. Observing Physical Properties

21. Observing Physical Properties

22. Physical Change • In a physical change, the substance involved remains the same (chemically). The substance may change form or state, however. All changes of state are physical changes. • Examples: Dissolving a substance in a liquid, breaking something. • NOTE: Most physical changes can be reversed.

23. Observing Chemical Properties • A chemical property describes the ability of a substance to change into a new substance or substances. • In order to view a chemical property a chemical changemust occur. • Chemical change - the formation of a new substance or substances with new properties. • A chemical reaction is a process in which a chemical change occurs.

24. Chemical Properties 1. Combustibility is the ability of a substance to burn. In order to burn a substance requires Oxygen

25. Chemical Properties • Light sensitivity is a chemical property of that can cause new substances to form when light hits it.

26. Chemical Properties 3. Reacting with an acid is a chemical property where when acid is poured on a substance it produces a gas and bubbles.

27. Clues that a chemical change has occurred

28. Clues that a chemical change has occurred

29. Summary • • All matter is composed of moving particles that attract one another but have spaces between them. • • Matter can be solid, liquid, or gas, or a combination of states and can change from one state to another. • • Elements and compounds are pure substances. Mechanical mixtures, suspensions, and solutions are combinations of pure substances.

30. Summary • • Physical properties are characteristics of a substance that can be observed or measured without changing what the substance is. Physical properties include boiling point, colour, conductivity, viscosity, and adhesion, cohesion, and other special properties of water that are important in living systems. • • Chemical properties describe how substances react with other substances or to light or heat and can be observed when chemical changes occur.

31. Key Terms • Read each one and then try to define it, if you do not know the meaning of it look it up in your notes and write it down.

32. The Periodic Table Organizes Elements by Patterns in Properties and Atomic Structure

33. Key Concepts • • Atomic theory • • Atomic models • • Subatomic particles • • Element names and symbols • • Properties of common elements • • Periodic table • • Properties of chemical groups

34. Evolving Models of the Atom • Atomic theory is the study of the nature of atoms and how they combine to form all types of matter. Atomic theory helps us to understand why there are different kinds of atoms. It explains how atoms combine to form over 100 known elements and all other forms of matter, including compounds and mixtures.

35. John Dalton (1766–1844), • a scientist and teacher in England, reconsidered the ancient idea that each different kind of element is composed of a different kind of atom. Dalton thought that the atom would be like a featureless sphere.

36. John Dalton (1766–1844), He used the following theory to explain the nature of matter: • All matter is made of small, indivisible particles called atoms. • All the atoms of an element are identical in properties such as size and mass.

37. John Dalton (1766–1844), • Atoms of different elements have different properties. • Atoms of different elements can combine in specific ways to form new substances. • Atoms cannot be created, destroyed, or subdivided in a chemical change.

38. J. J. Thomson (1856–1940), • He found that the atom is not the smallest particle. There were particles within the atom. • He theorized that an atom was a positively charged sphere with negative charges embedded in it.

39. J. J. Thomson (1856–1940), • In 1897 he proposed a revolutionary new model for atoms. It is known as the raisin bun model. The dough would be the positively charged sphere and the raisins would be the negative charges. It is also known as the plum pudding model

40. Ernest Rutherford (1891–1937) • Rutherford had discovered the nucleus, the centre of the atom. • This tiny positively charged part of the atom also contains most of the atom’s mass.

41. Atoms are composed of three subatomic particles • Protons-Heavy positively charged found in the nucleus • Neutrons -are neutral particles that have the same mass as protons and are located in the nucleus • Electrons-Negatively charged particles with almost no mass. They circle the nucleus at different energy levels.

42. Atoms are composed of three subatomic particles • Atoms are electronically neutral so the number of electrons = the number of protons

43. Niels Bohr (1885–1962),

45. The Elements • Elements are pure substances that consist of atoms. • The periodic table consists of over 100 elements all of which have a certain spot on the table.

46. Non-Metals • Found on the Right side of the periodic table • Most of the remaining elements in the periodic table are non-metals (17 of them).

47. Non-Metals Non-metals generally have these properties: • Non-conductor of electricity in its solid form • At room temperature most are gasses (11) or solids (5) and only one is liquid. • Solids are brittle and lack the lustre of metals

48. Metalloids • Found in the middle-right of the periodic table • Some elements do not fit as metals or non-metals. These fit on either side of the staircase that divides the metals and the non-metals. • They have some properties of metals and some properties of non-metals. They are called semiconductors because they do not conduct electricity well.

49. Metalloids • It is easier to control the flow of electricity through semiconductors than it is conductors, which explains their wide use in electronics.

50. Metalloids • Silicon is the most common metalloid, in its pure form it is shiny, grey and very brittle. Around 40% of all rock is silicon.