12.1 Properties of Solids

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 changeis 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.

3. 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.

4. 2.2 Density • Density describes how much mass is in a given volume of a material.

5. 12.1 Properties of Solids The density of a solid material depends on two things: • the individual mass of each atom or molecule, • how closely the atoms or molecules are packed together. Carbon atoms in diamond are packed very tightly.

6. 12.1 Properties of Solids • Paraffin wax is also mostly carbon, but its density is only 0.87 g/cm3. • 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

7. 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.

8. 2.2 Density of common materials • Density is a property of material independent of quantity or shape.

9. 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/cm3 or kg/m3.

11. 2.2 Density of common materials • Liquids tend to be less dense than solids of the same material. • Ex. solder (“sodder)

12. 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.

13. 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. • Mass is measured with a balance or scale. • Use the displacement method or calculate the volume.

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

16. 12.1 Mechanical properties • “Strength” describes the ability of a solid object to maintain its shape even when force is applied.

17. 12.1 Mechanical properties • Tensile strength is a measure of how much stress a material can withstand before breaking.

18. 12.1 Mechanical properties • Hardness measures a solid’s resistance to scratching. How might you compare the hardness of these two metals?

19. 12.1 Mechanical properties • Elasticitydescribes a solid’s ability to be stretched and then return to its original size. • Brittlenessis defined as the tendency of a solid to crack or break before stretching very much.

20. 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.

21. 12.1 Mechanical properties • Malleability measures a solid’s ability to be pounded into thin sheets. • Aluminum is a highly malleable metal.