Matter
1.2 Investigating Matter Matter is anything that has mass and volume. Mass is the amount of matter in a substance or object. Mass is often measured in grams or kilograms. Volume is the amount of space a substance or an object occupies. Volume is often measured in litres. See page 16
Chemical Change A chemical change is a change in matter that occurs when substances combine to form new substances. For example, fireworks See page 17
Physical Change and Changes of State When a physical change occurs, there may be a change in appearance, but no new substances are formed. For example, when ice or snow melts to water, this physical change is a change of state. No new substances are formed. See page 18
The Particle Model of Matter Describes the behaviour of matter Matter is made of small particles. There are spaces between the particles. Gases have more space than liquids. Liquids have more space than solids. Particles are always moving. Particles are attracted to each other. The strength of attraction depends on the type of particle. See page 18
Energy Kinetic vs potential energy Kinetic energy is the energy of movement Potential energy is the stored energy See page 16
Temperature and Changes of State See page 21 (c) McGraw Hill Ryerson 2007
Describing Matter Physical Properties Qualitative – properties that can be described but not measured. Ex. state, colour, malleability Quantitative – properties that can be measured numerically. Ex. conductivity, viscosity, density Pure Substances – made of only one type of matter. Element - a pure substance that cannot be broken down or separated into simpler substances (e.g., gold) Compound - a pure substance composed of at least two elements (e.g., water) Take the Section 1.2 Quiz See pages 22 - 23 (c) McGraw Hill Ryerson 2007
Heating Curve of Water Heating Curve of Water Activity Water molecules have a strong attraction to one another. Because of this property, water has high melting and boiling points and a high specific heat. In this activity, you will plot the heating curve of water and explain what each part of the curve represents at the molecular level. Procedure Use the data in the table to plot a heating curve of temperature versus time for a 180-g sample of water as it is heated at a constant rate from -20°C to 120°C. Draw a best-fit line through the points. Note the time required for water to pass through each segment of the graph.
Time and Temperature Data for Water Was there a control group used in this experiment? What is the dependent variable? What axis will it be graphed on? What is the independent variable? Why? What axis is it graphed on? What information is important to include in the graph’s title?
Dependent vs independent Independent variable: -YOU CONTROL THIS (time) Dependent variable: -IT IS WHAT YOU MEASURE (temperature) The dependent variable depends on the controlled (independent) variable! Its easier if you make a sentence: the temperature depends on the amount of time it has been on the hot- plate.
So which goes where??? This is what you measure= Dependent variable (in this experiment it was temperature) Y-axis X-axis: THIS IS THE VARIABLE YOU CONTROL = independent variable – here it was time
Water’s heating curve Time on hotplate (min)
The Kinetic Molecular Theory Describes what happens to matter when the kinetic energy of particles changes. The main points in the theory are: Matter is made of small particles. There is empty space between particles. Particles are constantly moving. Solid particles are packed together and cannot move freely. They can only vibrate. Liquid particles are farther apart and can slide past each other. Gas particles are far apart and move around quickly. Energy makes particles move. See page 19
The Kinetic Molecular Theory and Changes of State Solid Particles are close together, fixed in position and vibrating. Melting As temperature increases, particles’ kinetic energy increases. Liquid Particles are still close, but slide past one another. Boiling As temperature increases, particles’ kinetic energy continues to increase, creating more space. Gas Particles are highly energetic and moving freely. See page 20
As temperature increases, particles’ kinetic energy increases. As temperature increases, particles’ kinetic energy continues to increase, creating more space. Gas particles are far apart and move around quickly. Liquid particles are farther apart and can slide past each other. Particles are close together, fixed in position and vibrating.