Matter and Properties Big idea: Atoms are building blocks of matter, all substances have specific properties, and matter can be a pure substance or a mixture.

Matter and Properties Demonstration: Inflated and deflated ball. pg. 10 in Ch. 1 Measure the mass of the ball when inflated and deflated. Matter does not have to be visible and can be made of particles we can’t see. However, all matter has specific properties.

Matter and Properties We pumped air into the ball. The air has volume and mass. Volume is the amount of 3-D space an object occupies. Mass is a measure of the amount of matter. So, Matter is defined as anything that has mass and takes up space.

Matter and Properties What makes up the air in the ball? Atoms, they are the building blocks of matter. Atoms make up elements and compounds An atom is the smallest unit of an element that maintains the chemical identity of that element.

Matter and Properties An element is a pure substance that cannot be broken down into smaller, stable substances and is made up of one type of atom. Hydrogen is an element that only contains one kind of atom (Hydrogen). Only elements are found on the Periodic Table.

Matter and Properties A compound is a substance that can be broken down (chemically) into simple stable substances. Each compound is made from the atoms of two or more elements that are chemically bonded. Example: Hydrogen (an element) and Oxygen (an element) chemically bond to form Water (a compound).

Matter and Properties Passing electricity through water will separate it into hydrogen and oxygen again. Electrolysis Demo All substances (elements or compounds) have characteristic properties which are used to separate them. These properties can be used to identify unknown substances into groups. Properties can either be extensive or intensive.

Matter and Properties Extensive properties depend on the amount of matter that is present. Volume, mass, energy, time, length, weight, electrical charge. Example: Diamonds are cut into certain shapes and sizes to be used for rings. One gallon of gasoline has less energy than 15 gallons of gasoline.

Matter and Properties Intensive properties do not depend on the amount of matter present. Examples: density, elasticity, conductivity, hardness, magnetism, temperature, ductility, boiling point etc. Example: Diamonds will all have the same hardness regardless of shape and size. Gasoline is always flammable whether it's 1 gallon or 15 gallons.

Matter and Properties Lets focus on density (D=m/V) Density is the ratio of mass to volume, or mass divided by volume. A sample of aluminum metal has a mass of 8.4 g. The volume of the sample is 3.1 cm 3. Calculate the density of the aluminum.

Matter and Properties Physical properties and Physical changes Physical property is a characteristic that can be observed or measured without changing the identity of the substance. Examples: Density, boiling point, melting point, freezing point, etc. Physical change does not involve a change in the identity of a substance. Example: Grinding, cutting, melting, freezing, etc.

Matter and Properties Phase change is a physical change of a substance from one state to another. Example: solid to a liquid by heating States of matter Solid - has definite volume and definite shape. Liquid - has definite volume but no or indefinite shape. Gas - has neither definite volume or shape.

Matter and Properties Modeling states of matter Solid Liquid Gas Be familiar with evaporation, condensation, fluid, & compressibility

Matter and Properties Chemical properties and Chemical changes Chemical property relates to a substance’s ability to undergo changes that transform it into different substances. This property is easiest to see during a chemical reaction. Example: Carbon burning, milk souring, iron rusting, etc.

Matter and Properties A change in which one or more substances are converted into different substances is called a chemical change. The carbon burning with oxygen produces carbon dioxide and water vapor. New substances with different properties. During a chemical change, new substances are produced with different properties.

Matter and Properties How do we know if a chemical change has occurred? Temperature change Production of gas Precipitate Color change (not the best indicator)

Matter and Properties Energy and changes in matter Physical and chemical changes always involve energy. The energy involved takes different forms, the most familiar to us are heat and light. The energy can be absorbed or released in a change but not destroyed or created. The last two statements describe the law of conservation of energy.

Matter and Properties Matter can be a mixture of a pure substance. A mixture is a blend of two or more kinds of matter, each of which retains its own identity and properties. The parts or components of a mixture are physically mixed and can usually be separated. Mixtures are usually classified in terms of percentage by mass or volume. Example: A salt water solution might be 5% salt and 95% water by mass.

Matter and Properties Homogeneous mixtures (solution) are uniform in composition (they have the same proportion of components throughout). Example: Salt water (10% salt and 90% water) Heterogeneous mixtures are not uniform throughout. Example: Pieces of clay in water. Lighter pieces stay on top and heavier pieces fall to the bottom

Matter and Properties A pure substance has a fixed composition. They are always homogeneous and are either elements or compounds. Every sample of a given pure substance has exactly the same characteristic properties and the same composition. Example: Water (compound) is always 11.2% hydrogen and 88.8% oxygen can be a solid, liquid or gas.

Formative Assessment 1.What is the main difference between physical and chemical properties? 2.Give three examples of physical and chemical changes. 3.How do you decide where a sample of matter is a solid, liquid or gas? 4.Contrast Mixtures with pure substances.