Physical Properties Density

Changes of State: solid Definite shape and volume Do not expand or contract too much when heated or cooled. Particles are held closely together by strong attractive forces

Changes of State: liquid Take the shape of the container they are in, definite volume Pressure is exerted equally in all directions Held together by attractive forces Particles are not so close together so they are more mobile

Changes of State: gas No definite shape or volume, take shape and volume of the container they are in Temperature and Pressure affect gases: dramatically alters them Particles are very far apart, weak attractive forces between molecules allowing great mobility

density Mass per unit volume of a material Physics – kg/m3 Chemistry – g/mL or g/cm3 𝐷= 𝑚 𝑉 where D is density, m is mass and V is Volume Note: the Greek letter ρ is used for density as well.

applications Density determines the use of an element Aluminum (Al) is very light so is used for foil, aircrafts, boats, spacecraft, windmills, cars, tools, cans…

Calculations Silver in a lab has a mass of 42.0 g and occupies a volume of 4.00 cm3. Find the density of silver in this lab! D = m/V D = 42.0 g/4.00 cm3 D = 10.5 g/cm3

Numbers with units substituted in Answer rounded to match question Marking system Marks given for: Formula stated Numbers with units substituted in Answer rounded to match question Answer with units

Summary YOU CAN IDENTIFY UNKNOWN MATERIALS BASED ON DENSITY, MELTING POINT, BOILING POINT, FREEZING POINT. These are called Characteristic Physical Properties as they can be used to identify certain materials.

pg. 193 - define FP, MP, BP, read about Salt and Water Class/home work pg. 193 - define FP, MP, BP, read about Salt and Water pg. 198 #1-12. (use charts on page 193, 195)