1. DENSITY How dense is dense?

2. What’s the matter? Matter exists in 3 main forms: solid liquid and gas. Density is the concentration of matter (atoms) in a substance. Silicon atoms

4. Density is a ratio The density of an object is the ratio of its mass (g) to its volume (cm 3 or ml). ABC

5. Density calculations convert to metric 7 X 3.625 X 1.75in. 2.54cm = 1 inch Length = ? Width = ? Height = ? Volume = ? 454g = 1lb Mass = 30.98lb Mass = ?

6. Density equation Density = Mass Volume D = M V D M V

7. Density calculations 7 X 3.625 X 1.75in. 2.54cm = 1 inch Length = 17.78cm Width = 9.21cm Height = 4.45cm Volume = ? 454g = 1lb Mass = 30.98lb Mass = 14,064.9g

8. Work Volume 17.78cm X 9.21cm X 4.45cm = 728.7 cm 3 Volume = 728.7 cm 3 Mass 30.98lb X 454g = 14,064.9g 1lb Mass = 14,064.9g

9. More work D = M V D = 14,064.9g 728.7 cm 3 D = ?

10. More work D = M V D = 14,063.9 g 728.7 cm 3 D = 19.3 g/cm 3

11. Are we correct? Densities of Common Elements and Compounds Substance Density (g/cm 3 ) Water1.00 Aluminum, Al 2.70 Iron, Fe 7.80 Gold, Au 19.30 Mercury, Hg 13.50

13. Effect of phase of matter on density Most substances increase in density as they change from gas to liquid to solid. Quite simply, the atoms are closest together in the solid phase. gas  liquid  solid increasing density decreasing density

14. Water is an exception ice liquid water water vapor Water is densest as a liquid at 3.98 o C. That’s why ice floats.

16. Size or shape does not affect the density of a substance = same density

17. Even when cut, the density of a substance remains the same.

18. Factors that affect density Temperature –Heat - pushes molecules apart –Cold - pushes molecules together Pressure –Low - allows molecules to spread apart –High - pushes molecules together It’s the volume that changes and density is dependent on the ratio d=m v

19. Float? If the density of an object is less than the liquid it will float. The lower the density of an object the higher it will float in the liquid.

20. Sink? If the density of an object is greater than that of the liquid, it will sink.

21. ??? If an object and a liquid have the same density, the object can remain stationary anywhere in the liquid.

22. Layering Liquids of different densities will form layers. http://www.youtube.com/watch?v=-CDkJuo_LYs