8 th grade Science

1. 8th grade Science Post 2 Review

2. Anything that has volume or mass Matter

3. Volume The amount of space taken up measured in a measuring cylinder read it at the bottom of meniscus SI unit = cm3

4. Matter is not created or destroyed Law of conservation of matter

5. Mass Amount of matter in a substance SI unit = kg

6. Weight Measure of the gravitational force SI unit= Newton’s Will change if gravity changes

7. Density The amount of matter in a given amount of space SI Unit= g/cm3

8. The smallest particle into which an element can be divided and still be the same substance. Atoms

9. A neutral group of atoms held together by bonds. Molecule

10. A pure substance that cannot be broken down into anything smaller. Can be found in the periodic table. Ex. oxygen Element

11. A pure substance that is made up of 2 or more elements that are chemically combined. Ex salt Compound

12. Consist of 2 or more elements or compounds that are not chemically combined. Ex salt and pepper, oil and vinegar. Mixture

13. Particles are close together and only vibrate. Fixed volume and shape. Solid

14. Liquid Particles are close together and can slide over one another. Fixed volume but can take the shape of the container.

15. Gases Particles are far apart and have a lot of energy and movements. Changeable volume and shape.

16. Plasma Particles have broken apart, composed of electrons and positively charged ions. Changeable volume and shape.

17. Table containing more than 100 elements Periodic Table

18. How is the Periodic Table arranged? It is arranged in order of increasing atomic number.

19. What does the atomic number tell you? The number of protons in an atom.

20. Columns These are the groups on the periodic table they contain elements that are similar. Each element has similar characteristics Ex: Group 1 all reactive with water, metals, and can cut easily.

21. Rows = Periods

22. This person saw that the properties were periodic, they were in a regular pattern. Mendeleev

23. Name the element • C= Carbon • Na= Sodium • H= Hydrogen • O= Oxygen

24. Name the element • Fe= Iron • He= Helium • Cl= Chlorine

25. Zigzag • The _______________ line separates the metal from non metals and metalloids. • Metals are on the left of the line.

26. Metals • These elements are to the left of the line, most are solid at room temperature, except mercury. Malleable, good conductors, ductile, shiny.

27. Nonmetals • These elements are to the right of the line. They are not shiny, not malleable or ductile.

28. Metalloids • These elements border the zigzag line. Some properties of metals and some are nonmetals.

29. What elements are in Group 1? Alkali metals

30. What elements are in Group 2? Alkaline-earth metals

31. What elements are in Groups 3-12? Transition metals

32. What elements are in the last group 8/16? Nobel Gases

33. What is special about the noble gases? • They do not react, and have a full valance shell (outer shell).

34. Nucleus • The _____________ contains protons (positive) and neutrons (neutral) of the atom, and is your atomic mass in the periodic table.

35. Electrons • __________ are found on the shells or clouds of the atom and are negative.

36. Valance electrons • The are electrons found in the outer shell of the atom.

37. How many electrons are in the first shell of an atom? 2

38. How many electrons are in the other shells of an atom? 8

39. Physical properties Properties that can be observed or measured- weight, mass, volume, density, color, state of matter, malleability, ductility, solubility, thermal conductivity.

40. Chemical Properties Describes a substance based on its ability to change into a new substance- flammability, how it reacts with different substances.

41. Physical change Change that affects one or more of the physical properties- examples- state changes. Sanding wood, breaking something, cutting your hair, mixing oil and water, dissolving anything.

42. Chemical Change Change that happens when the substance changes into something new. Forms something new! Ex: souring milk, oxidation (Statue of Liberty rusting), hot gas forming when oxygen and hydrogen combine. Clues to when it has happened= bubbles or fizzing, change of color, production of heat, light, sound, smell, or formation precipitate and are difficult to get back.

43. Motion When an object changes position over time when compared to a reference point. Reference points can be Earth, buildings, ect.

44. Speed The rate at which an object moves. SI unit= meters per second. m/s= average speed= total distance divide by total time.

45. Velocity The speed of an object in a particular direction. Combining velocities is called resultant velocity.

46. Acceleration The rate at which velocity changes= final velocity minus starting velocity divided by time. Expressed in m/s/s.

47. Force A pull or push and is measured in Newtons.

48. Net force If two forces act on the same object you will get a ___________ __________.

49. zero If net force is ________ then the forces are balanced, object remains at a constant speed or stationary.

50. unbalanced If the net force is greater than zero, the forces are _____________ then it will accelerate.