Chapter 2: Matter and change

What is the difference between an Extensive and an Intensive property?

● Extensive Property: Property that depends on the amount of matter in a sample

○ Examples: Mass (the amount of matter in an object)○ Volume (The measure or space that an object takes up)

● Intensive Properties: Property that depends on the type of matter in a sample, NOT the amount of matter

○ Example: colour, hardness

How can you identify a substance? ● A substance is any matter that has a uniform and

definite composition○ Sometimes referred to as a pure substance:○ Copper watering can and copper wire have same intensive

properties

● Physical properties can be used to identify a substance

○ A physical property is a quality or condition of a substance that can be observed or measured without changing the substance’s composition

○ Examples include melting point, boiling point, color

● Every sample of a given substance has identical intensive properties because every sample has the same composition

What are three states of matter? What are the characteristics of each state?

What is a vapor? What is the difference between a gas and a vapor?

● A gas is a substance that exists in a gaseous state at room temperature (eg. oxygen)

● A vapor describes the gaseous state of a substance that is usually solid or liquid at room temperature - for example, water

What is a physical change? What does it do? ● A physical change alters some of the properties of a material, but it does not

change the composition of the material ○ Example - Ice melting into water

● Physical changes can be reversible or irreversible ○ Freeze, melt and condense all refer to physical changes○ Tear, break, cut, crush describe irreversible changes

What is a the difference between a homogenous and a heterogenous mixture?● A mixture: A physical blend of two or more

components or parts● Heterogenous mixture: Does not have a

uniform composition throughout● Homogenous mixture: A mixture that does

have a uniform composition throughout○ A solution is another name for a homogenous mixture○ A solution does not have to be a solid!

How can mixtures be separated? ● Filtration: Example coffee filter - solid particles are too big to pass

through the filter● Distillation: Process to separate water from other substances

What is the difference between an element and a compound?● An element is the simplest form of matter that has a unique set of properties● An element cannot be broken down into a simple substance● Compounds can be broken down into a simpler substance - example: sugar,

composed of carbon, hydrogen and oxygen○ The properties of compounds are often very different than their constituent elements

What is a chemical change? ● A chemical change is a change that

produces matter with a different composition than that of the original matter

● Cannot be accomplished through physical methods

● Heating can break down some compounds into simpler substances (but not all)

How can you distinguish between a substance and a mixture? ● If the composition of a material is fixed then the material is a substance● If the composition of a material may vary, the material is a mixture

Why do chemists use chemical symbols and formulas?

● Chemical symbols are used to show the elements that make up matter● Each element has a chemical symbol made of one or 2 letters

○ First letter is always capitalized

● Many symbols are based on latin names (blame Jons Jacob Berzellius - 1779 - 1848)

What is so great about chemical symbols? ● Chemical Symbols are a quick way to write the chemical formulas of

compounds● The symbols for Carbon, Hydrogen, and Oxygen are C, H & O● C12H22O11 = Sucrose

What is special about the periodic table?

● Period = Rows● Groups = Columns

What is the difference between a physical and a chemical change? Physical change: No change in coomposition of matter

Chemical change: change in chemical compositon

What is a chemical reaction? ● Another name for a chemical change ● Reactant - Substance present at the start of a reaction● Products - Substance that is produced

How can you tell that a chemical reaction has taken place?● Energy transfer

○ Every chemical reaction involves a transfer of energy

● Colour change● Formation of a precipitate● Production of a gas● Just because you see one of these

clues, does not mean that a reaction has definitely taken place!

What is the law of conservation of mass?

● The total mass of the products is always the same as the total mass of the reactants - the law of conservation of mass

● During any chemical reaction, the mass of the products is always equal to the mass or the reactants