1. 12.1 Properties of Solids  Different kinds of matter have different characteristics.  Characteristics that can you observe directly are called physical properties.  Physical properties include color, texture, density, brittleness, and state (solid, liquid, or gas). Ex. Iron is solid at room temp.

2. 12.1 Properties of Solids  A physical change is any change in the size, shape, or phase of matter in which the identity of a substance does not change.  For example, when water is frozen, it changes from a liquid to a solid.

4. 12.1 Properties of Solids  Properties that can only be observed when one substance changes into a different substance are called chemical properties.  Any change that transforms one substance into a different substance is called a chemical change. Ex. If you leave a nail outside, it rusts.

5. 2.2 Density  Density describes how much mass is in a given volume of a material.

6. 12.1 Properties of Solids The density of a solid material depends on two things: 1.the individual mass of each atom or molecule, 2.how closely the atoms or molecules are packed together. Carbon atoms in diamond are packed very tightly.

7. 12.1 Properties of Solids  Paraffin wax is also mostly carbon, but its density is only 0.87 g/cm 3.  Paraffin’s carbon atoms are mixed with hydrogen atoms in long molecules that take up more space. The density of paraffin is low compared to diamond

8. 2.2 Density  Solids, liquids and gases are matter, so they all have density.  The density of water is about one gram per cubic centimeter.

9. 2.2 Density of common materials  Density is a property of material independent of quantity or shape.

10. Two units of density are g/mL and g/cm 3. 1 ml = 1 cm 3

11. 2.2 Density  The units used for density depend on whether the substance is solid or liquid.  For liquids use units of grams per milliliter (g/mL)  For solids use density in units of g/cm 3 or kg/m 3.

13. 2.2 Density of common materials  Liquids tend to be less dense than solids of the same material.  Ex. solder (“sodder)

14. 2.2 Density of common materials  Water is an exception to this rule.  The density of solid water (ice) is less than the density of liquid water.

17. 2.2 Determining Density  To find the density of a material, you need to know the mass and volume of a solid sample of the material. 1.Mass is measured with a balance or scale. 2.Use the displacement method or calculate the volume.

19. Calculating Density 1.Looking for:  …the density of the candle 2.Given:  …mass = 15.0 g; volume = 17.0 mL 3.Relationship:  D = m/V # Sig. fig =.882 g/mL Solving Problems 4.Solution:  15.0 g ÷ 17.0 mL = 0.8823529 g/mL

20. 12.1 Mechanical properties  “Strength” describes the ability of a solid object to maintain its shape even when force is applied.

21. 12.1 Mechanical properties  Tensile strength is a measure of how much stress a material can withstand before breaking.

22. 12.1 Mechanical properties  Hardness measures a solid’s resistance to scratching. How might you compare the hardness of these two metals?

23. 12.1 Mechanical properties  Elasticity describes a solid’s ability to be stretched and then return to its original size.  Brittleness is defined as the tendency of a solid to crack or break before stretching very much.

24. 12.1 Mechanical properties  A ductile material can be bent a relatively large amount without breaking.  The ductility of many metals, like copper, allow then to be drawn into wire.

25. 12.1 Mechanical properties  Malleability measures a solid’s ability to be pounded into thin sheets.  Aluminum is a highly malleable metal.