Section 4.2 of the textbook pp. 149 -155 Properties of Matter Section 4.2 of the textbook pp. 149 -155

Physical Properties Physical properties are characteristics or descriptions of a substance that may be observed or measured. The substance remains the same, it is not made into a new substance, when you observe physical properties.

Physical Properties In determining the properties of a substance, you make qualitative or quantitative observations.

Quantitative Observations Quantitative observations – observations made using tools to measure various properties of a substance numerically. e.g. temperature, volume, mass, length, density

Qualitative Observations Qualitative observations – observations that are descriptive and require no measurement. They are usually determined through the use of your senses (sight, smell, taste, touch or hearing). **Using the senses of taste, touch and smell may be hazardous!! WHY?

Physical Properties of Matter Colour – is observed with your sense of sight, and is related to the reflection of different wavelengths of light off of the surface of an object. E.g. a green object is reflecting green light which reaches your eye. For more info, go to this website: http://www.artsparx.com/seeingcolor.html

Colour vision When you see colour, you are seeing the light that reflects from an object. The lemon reflects yellow light and absorbs the other colours of light.

Physical Properties of Matter Texture – observed using your sense of touch. It is how a substance feels. Examples of textures are scratchy, rough, bumpy, smooth. If the substance being observed is sharp, poisonous or corrosive, it will be dangerous to observe this property. Check with your teacher first

Physical Properties of Matter Lustre – the visual property of how well a substance shines with reflected light. There are 2 descriptors for this property: Shiny – the substance reflects light well Dull – the substance does not shine with reflected light.

Physical Properties of Matter Clarity – the ability to see an object or light through another object. There are three degrees of clarity:

Clarity Transparent – able to see an object and light through the object without obstruction. May be described as clear.

Clarity Translucent - allowing light to pass through but diffusing it so that objects on the opposite side are not clearly visible, but are still slightly visible. The circle shown here is translucent.

Clarity 3. Opaque – not allowing light or an image to be seen though. The grey side of this oval is opaque.

Physical Properties of Matter State of Matter – this property relates to the shape and volume occupied by substances. The state is related to how the particles in an object are connected together.

State of Matter Solids – maintains its shape and volume, no matter what type of container they are placed in. The particles pack together tightly.

State of Matter Liquids – maintain their volume but will change to take the shape of their container

State of Matter Gases – take on the shape and volume of (will fill up) their container. The particles move quickly and randomly.

State of Matter

Physical Properties of Matter Hardness – the ability of an object to resist being scratched. This property is observed by comparing two substances.

Hardness Objects may be hard (can scratch another substance) or soft (able to be scratched). E.g. If a diamond is rubbed on a mirror with enough force it may scratch the mirror. The diamond is hard, and the mirror is soft.

Physical Properties of Matter Malleability – the ability of metals to be hammered into thin sheets, or to be shaped (bent) without breaking. Objects may be malleable (bendable, e.g. aluminum) or brittle (will break on bending, e.g. chalk)

Physical Properties of Matter Ductility – the ability of a metal to be stretched into a long wire. The most ductile metals are gold, silver, aluminum and copper.

Physical Properties of Matter Melting Point – the temperature at which a solid will become a liquid. E.g. The melting point of gold is 1064 degrees Celcius

Physical Properties of Matter Boiling Point – the temperature at which a liquid becomes a gas. E.g. the boiling point of gold is 2856 degrees Celcius

Physical Properties of Matter Crystal Form – a description of the shape of solid crystal substances. There are a number of different shapes, but in this course we are concerned with only 4 crystal forms:

Crystal Form Cubic

Crystal Form Granular (irregular)

Crystal Form Powder

Crystal Form Hexagonal

Physical Properties of Matter Solubility – the ability of a substance (called a solute) to dissolve in another substance (called a solvent). Substances that dissolve are soluble. Substances that do not dissolve are insoluble.

Physical Properties of Matter Viscosity – the resistance of a liquid to flow or pour. High viscosity liquids pour very slowly (with high resistance to flow). Low viscosity liquids pour very easily (with low resistance to flow).

Viscosity Low High

Physical Properties of Matter Density –compares the mass to the volume of a substance (mass by comparison to size). Density is important in determining buoyancy of one substance in another. An object must be less dense than other to float.

Density The green liquid is less dense than the blue liquid. Which liquid is the most dense?

Physical Properties of Matter Conductivity – the ability of an object to carry electricity or heat. Most metals are good conductors. A conductor carries heat or electricity well. An insulator does not carry heat or electricity well.

Chemical Properties of Matter Chemical properties are characteristics or descriptions of an object determined by reacting the substance with another substance. To determine chemical properties, the original substance may be changed into a new substance with different properties.

Chemical Properties of Matter Combustion – the ability of an object to burn. In combustion reactions, a substance burns in the presence of oxygen (the substance reacts with oxygen in the air).

Combustion

Chemical Properties of Matter Reaction with Acid – an object may change its form or react (e.g. dissolve, bubble, explode, release heat) in the presence of acid. Not all substances react with acid.

Light Sensitivity Some chemicals are so unstable, that they will get enough energy from light to make them break down into other substances. Hydrogen peroxide and some prescription drugs will do this. If the label says keep in a dark place, it is for this reason.

Light Sensitivity

Reaction with Other Chemicals When different chemicals react, they will produce new substances with obviously different properties e.g. new gas new colour energy is released (heat, sound, light) energy is absorbed (feels cold) new solid produced (precipitate)