Physical & Chemical Properties & Changes Miss Sauer’s 7 th Grade Science

Do Now: 1. What is an observation? 2. Are measurements observations? 3. What is matter? Changes in the Properties of Matter Physical and Chemical: (29:53 mins) Information collected using our five senses. Yes, they are extensions of our observations. Anything that takes up space and has mass.

Physical and Chemical Properties

Properties of Matter-Words to Know…

Anything that has mass and takes up space! Matter

Mass A measure of how much matter is in an object.

Weight A measure of the force of gravity on an object.

Volume The amount of space that matter occupies.

Density The measurement of how much mass of a substance is contained in a given volume. Mass/Volume I Density

States of Matter There are different “states” of matter. No, not like Texas, Oklahoma, New Mexico. States of matter are also known as phases (a physical state of matter). Elements and compounds can move from one phase to another phase when special physical forces are present. Solid Liquid Gas

Freezing point The temperature at which a liquid changes into a solid.

Boiling point The boiling point of an element or compound means the temperature at which the liquid form of an element or compound is at equilibrium with the gaseous form. the boiling point of water is 100 degrees Celsius.

Melting point The temperatures at which the solid form of the element or compound is at equilibrium with the liquid form. Basically the range at which the solid changes its state into a liquid. The melting point of water is 0 degrees Celsius

Compound A substance made of two or more elements chemically combined in a set ratio. Water and salt are 2 examples of compounds.

All substances have properties… Including people! Example: People can be identified by their … Face ( shape, expressions ) VoiceHeightFinger prints Eye colorHair colorTeethDNA

Physical Properties Physical properties are used to identify matter. Thermal ConductivityThe ability to transfer (heat) thermal energy from one area to another. Plastic foam is a poor conductor, but good for hot beverages. StateSolids, Liquids, GasesIce, Water, Steam MalleabilityAbility to be pounded into thin sheets.Aluminum Foil DuctilityThe ability to be pulled into wire.Copper used for wiring SolubilityThe ability to dissolve in another substance. Sugar dissolves in water DensityMass per unit volume. D=m/vLead is used for sinkers, they are more dense than water

What are properties? Matter has observable and measurable qualities. We can use general properties to identify substances. Two basic types of properties of matter: Physical properties and Chemical properties:

Physical Properties Physical properties are used to identify, describe and classify matter. Characteristic of a substance that can be observed (using your senses) without changing the substance into something else. HardnessTextureColor OdorTasteTemperature

A. Physical Property A characteristic of matter that can be observed or measured without changing the identity of its matter. can be used to separate mixtures EX: density, color, odor, mass and volume

Physical Properties Physical properties can be extensive or intensive: Extensive properties depend on the amount of a substance that you have. Intensive properties don’t depend on how much you have.

Physical Properties - Examples Examples of extensive physical properties include: Volume Mass Weight Size

Physical Properties - Examples Examples of intensive physical properties include: Density Melting point Boiling point

Physical Properties - Examples Other physical properties include: Color Hardness Odor Taste State of matter Texture Luster (shine) Flexibility Heat conductivity Electrical conductivity Solubility (ability to dissolve in water.) Shape Viscosity Ductility Malleability

Physical properties List as many physical properties as you can for this item:

More EXAMPLES - Physical size, shape, freezing point, boiling point, melting point, magnetism, viscosity, density, luster and many more. Viscosity - The resistance of a liquid to flowing. Examples: Low viscosity-water, rubbing alcohol High viscosity-honey

Chemical Property A characteristic that indicates whether a substance can undergo a specific chemical change. EX: flammability, reactivity

Chemical Properties Chemical properties are characteristics involved when a substance interacts with another substance to change its chemical make-up. FlammabilityRustingCreating gas bubbles Creating a new chemical product Reactivity with water pH

Chemical properties A Chemical property is a characteristic of a substance that can only be observed by changing it into a different substance.

Chemical properties - Examples Examples of chemical properties include: The ability to burn Ability to tarnish Ability to rust Ability to decompose Ability to react with other chemicals Instability Ability to do acid/base reactions

Chemical properties List as many chemical properties as you can for this item:

Alike? Different? Draw a double bubble map in your notes to compare and contrast physical and chemical properties.

Chemical and Physical Changes

Physical Change Physical changes occur when matter changes its property but not its chemical nature. Physical changes could include a change in: texture, shape, size, color, odor, volume, mass, weight, and density.

Physical Change Remember! properties remain the same reversible can be used to separate mixtures

Physical Change

A Physical change is a change in a substance that does not change what the substance is.

Physical Change - Examples Examples of physical change include: Change in shape Change in size Change in phase Melting (solid to liquid) Boiling (liquid to gas) Evaporation (liquid to gas) Condensation (gas to liquid) Freezing (liquid to solid) Sublimation (solid to gas) Deposition (gas to solid)

Physical Change Physical changes might be caused by: Grinding Cutting Crushing Bending Breaking Heating/cooling (change in phase) squishing

Physical Change Evidence that a physical change has occurred might include: Change in shape Change in form Change in size Change in phase (This is always a physical change!) Physical changes are usually reversible

Physical change What could you do to these items to cause a physical change to occur?

Chemical Change Chemical changes are changes matter undergoes when it becomes new or different matter. To identify a chemical change look for signs such as color change, bubbling and fizzing, light production, smoke, and presence of heat.

Chemical Change Remember! properties change irreversible Signs: color change, formation of a gas/solid, release of light/heat

Chemical Change A chemical change occurs when fireworks are used. Fireworks are made of metals such as magnesium and copper. These change chemically as they light up the sky.

Chemical Change A chemical change is a change in which a substance is changed into a different substance. (You’ve changed what it is.)

Chemical Change Examples of chemical changes include: Burning Rusting Tarnishing Decomposing Polymerization

Chemical Change Chemical changes occur when a chemical reaction causes bonds between atoms to break or to form.

Chemical Change – Chemical Reactions There are 5 types of chemical reactions that cause chemical changes to occur.

Chemical Change – Chemical Reactions 1- Composition reactions Two things come together to form something new A + B = AB 2H 2 + O 2  2H 2 O

Chemical Change – Chemical Reactions 2- Decomposition reactions 1 thing breaks apart to form 2 or more things. AB = A + B 2H 2 O  2H 2 + O 2

Chemical Change – Chemical Reactions 3- Single replacement reactions One atom replaces another atom A + BC = AC + B or A + BC = AB + C Mg + 2HCl  H 2 + MgCl 2

Chemical Change – Chemical Reactions 4 - Double replacement reactions Two chemicals switch places AX + BY = AY + BX 2KI + Pb(NO 3 ) 2  PbI 2 + 2KNO 3

Chemical Change – Chemical Reactions 5 - Combustion reaction A substance combines with oxygen and releases energy. C 3 H 8 (propane) + 5O 2  3CO 2 + 4H 2 O

Chemical Change: Evidence Evidence that a chemical change has occurred might include: A color change An odor change Formation of a precipitate (you mix two liquids and make a solid) Gas is formed (bubbles) Changes in physical properties.

Physical and Chemical Change During a chemical change energy can be released in the form of: Heat Light

Chemical Change – Chemical Reactions When a chemical change occurs, energy is either released or absorbed.

Physical and Chemical Change - Heat A chemical reaction that releases energy in the form of heat is called exothermic. Heat comes OUT Exo = out Thermic = heat It will feel HOT.

Physical and Chemical Change - Heat A chemical reaction that absorbs energy in the form of heat is called endothermic. Heat goes IN Endo = in Thermic = heat It will feel COLD

Evidence of Chemical Change Bubbles of gas appear A precipitate forms A color change occurs The temperature changes Light is emitted

Common examples of chemical changes that you may be somewhat familiar with are; digestion, respiration, photosynthesis, burning, and decomposition.

Physical or Chemical Change? Painting Wood PHYSICAL

Physical or Chemical Change? Burning Paper CHEMICAL

Physical or Chemical Change? Digestion of food CHEMICAL

Physical or Chemical Change? Sugar dissolving in water PHYSICAL

Physical or Chemical Change? Iron turning red when heated PHYSICAL

Physical or Chemical Change? Evaporation PHYSICAL

Physical or Chemical Change? A pond freezing in winter PHYSICAL

Physical or Chemical Change? Melting ice PHYSICAL

Physical or Chemical Change? Cutting wire PHYSICAL

Physical or Chemical Change? Painting fingernails PHYSICAL

Physical or Chemical Change? Cutting fabric PHYSICAL

Physical or Chemical Change? Baking muffins CHEMICAL

Physical or Chemical Change? Shattering glass PHYSICAL

Physical or Chemical Change? Decomposition of old leaves CHEMICAL

Physical or Chemical Change? Wrinkling a shirt PHYSICAL

Physical or Chemical Change? An old nail rusting CHEMICAL

Closure Questions Differences between physical and chemical properties. Examples of physical properties. Examples of chemical properties. Differences between physical and chemical changes. Examples of physical changes. Examples of chemical changes.