Foundations of Chemistry Chapter 7

Physical Properties In Lesson 1, we learned the arrangement of atoms determines whether matter is a substance or a mixture. The arrangement of atoms also determines the properties of different types of matter. Each element and compound has a unique set of properties. When substances mix together and form mixtures, the properties of the substances that make up the mixture are still present. You can observe some properties of matter. For example, you can see that gold is shiny. You can measure other properties of matter. For example, you can measure the mass of a sample of iron. physical property- a characteristic of matter that you can observe or measure without changing the identity of the matter.

States of Matter How do aluminum, water, and air differ? Recall that aluminum is an element, water is a compound, and air is a mixture. How else do these three types of matter differ? At room temperature, aluminum is a solid, water is a liquid, and air is a gas. Solids, liquids, and gases are called states of matter. The state of matter is a physical property of matter. Substances and mixtures can be solids, liquids, or gases. For example, water in the ocean is a liquid, but water in an iceberg is a solid. In addition, water vapor in the air above the ocean is a gas. The particles (atoms or groups of atoms) that make up all matter move constantly and attract each other. Your pencil is made up of trillions of moving particles. Every solid, liquid, and gas is made up of moving particles that attract one another. The state of matter depends on how close together the particles are and how fast they move.

States of Matter SOLID The particles in a solid are very close together. They can move only by vibrating back and forth. This is why solids cannot easily change shape. LIQUID The particles in a liquid are slightly farther apart than in a solid. Therefore, the particles can move past one another. This is why you can pour a liquid. GAS The particles in a gas are farther apart. They move quickly and spread out to fill their container.

States of Matter OuTDOOR ACTIVITY Moving like a state

States of Matter Notebook ACTIVITY Create a thinking map similar to the sample to the right using your own examples. Examples must be written as well as drawn. Include a minimum of 6 examples for each state. NEATNESS COUNTS

Size-Dependent Properties State is only one of many physical properties of matter. Some physical properties depend on the size or the amount of matter. Measurements of these properties vary depending on how much matter is in a sample.

Size-Dependent Properties MASS is the amount of matter in an object. Mass is a size dependent property of a given substance because its value depends on the size of a sample. WEIGHT is the pull of gravity on that matter. An object’s mass and weight are not the same. Weight changes with location, but mass does not. VOLUME is the amount of space something takes up. A unit often used to measure volume is the milliliter (mL). Volume is a size dependent property of a given substance because its value depends on the size of a sample.

Size-INDependent Properties Some physical properties of a substance do not depend on the amount of matter present. These properties are the same for small samples and large samples. They are called size independent properties. Size-independent properties conductivity, boiling and melting points, state, density, solubility, and magnetism

Size-INDependent Properties the ability of matter to conduct, or carry along, electricity or heat Metals tend to have high electrical and thermal conductivity CONDUCTIVITY melting point temperature at which a substance changes from a solid to a liquid boiling point temperature at which a substance changes from a liquid to a gas MELTING AND BOILING POINTS is the ability of one substance to dissolve in another does not change for different volumes of a substance. SOLUBILITY attractive force for some metals, especially iron Magnetism is the mass per unit volume of a substance. DENSITY

Separating Mixtures In Lesson 1, we learned about different types of mixtures. Remember: the substances that make up mixtures are not held together by chemical bonds. When substances form a mixture, the properties of the individual substances do not change. the individual substances can be separated out of most mixtures by using differences in their physical properties. For example, when salt and water form a solution, the salt and the water do not lose any of their individual properties. Therefore, you can separate the salt from the water by using differences in their physical properties. Water has a lower boiling point than salt. When you boil salt water, the water evaporates, and the salt remains. You cannot use physical properties to separate a compound into the elements it contains. The atoms that make up a compound are bonded together and cannot be separated by physical means. For example, you cannot separate the hydrogen atoms from the oxygen atoms in water by boiling water.

PHYSICAL PROPERTY Separating Mixtures MASS VOLUME WEIGHT CONDUCTIVITY BOILING/ MELTING POINT DENSITY SOLUBILITY MAGNETISM STATE How the property is used to separate a mixture Mass typically is not used to separate a mixture. Volume could be used to separate mixtures whose parts can be separated by filtration. Weight typically is not used Conductivity typically is not used to separate a mixture. Each part of a mixture will boil or melt at a different temperature. Objects with greater density sink in objects with less density. Dissolve a soluble material to separate it from a material with less solubility. Use a magnet to attract iron shavings from a mixture of metals. A liquid can be poured off a solid.

QUIZ Tomorrow

Lesson 2 - summary A physical property is a characteristic of matter that can be observed or measured without changing the identity of the matter. Examples of physical properties include mass, density, volume, melting point, boiling point, state of matter, and solubility.

Lesson 2 - summary Many physical properties can be used to separate the components of a mixture.

Which term refers to properties that are the same for both small samples and large samples? A. size-dependent properties B. size-independent properties C. physical properties D. density

Lesson 2 – LR2 Which is the ability of one substance to dissolve in water? A. solubility B. mass C. density D. boiling point

Lesson 2 – LR3 Which refers to the amount of space something takes up? A. density B. mass C. physical property D. volume

7.3 Physical Changes How can a change in energy affect the state of matter? What happens when something dissolves? What is meant by conservation of mass?

Physical Changes physical change Create a 1-tab vocabulary foldable

Physical Changes (cont.) A physical change is a change in size, shape, form, or state of matter in which the matter’s identity stays the same. physical from Greek physika, means “natural things” change from Latin cambire, means “to exchange”

Physical change During a physical change, the matter does not become something different even though physical properties change.

How can a change in energy affect the state of matter? When thermal energy is added to a solid, the particles in the solid move faster and faster, and the temperature increases. When the particles are moving too fast for attractive forces to hold them tightly together, the solid reaches its melting point.

Physical Changes (cont.) When the particles in a liquid are moving so fast that attractive forces cannot hold them close together, the liquid reaches its boiling point. Sublimation occurs when a solid changes directly to a gas without first becoming a liquid.

As thermal energy is added to a material, temperature increases when the state of the material is not changing. Temperature stays the same during a change of state. Lesson 3-1

How can a change in energy affect the state of matter? When thermal energy is removed from a gas, particles in the gas move more slowly and the temperature decreases. Condensation occurs when the particles are moving slowly enough for attractive forces to pull the particles close together. After the gas has completely changed to a liquid, removing more thermal energy from the liquid causes particles move even more slowly.

How can a change in energy affect the state of matter? Freezing occurs when the particles are moving so slowly that attractive forces between the particles hold them tightly together. Deposition is the change from a gas directly to a solid. Deposition

Physical Changes (cont.) How can removing thermal energy affect the state of matter?

Activity- Make Ice Cream in a Baggie Freezing Point Depression and Colligative Properties Procedure Add 1/4 cup sugar, 1/2 cup milk, 1/2 cup whipping cream, and 1/4 teaspoon vanilla to the quart ziplocTM bag. Seal the bag securely. Put 2 cups of ice into the gallon ziplocTM bag. Use a thermometer to measure and record the temperature of the ice in the gallon bag. Add 1/2 to 3/4 cup salt (sodium chloride) to the bag of ice. Place the sealed quart bag inside the gallon bag of ice and salt. Seal the gallon bag securely. Gently rock the gallon bag from side to side. It's best to hold it by the top seal or to have gloves or a cloth between the bag and your hands because the bag will be cold enough to damage your skin. Continue to rock the bag for 10-15 minutes or until the contents of the quart bag have solidified into ice cream. Open the gallon bag and use the thermometer to measure and record the temperature of the ice/salt mixture. Remove the quart bag, open it, serve the contents into cups with spoons and ENJOY! Materials 1/2 cup milk 1/2 cup whipping cream (heavy cream) 1/4 cup sugar 1/4 teaspoon vanilla or vanilla flavoring (vanillin) 1/2 to 3/4 cup sodium chloride (NaCl) as table salt or rock salt 2 cups ice 1-quart ZiplocTM bag 1-gallon ZiplocTM bag themometer measuring cups and spoons cups and spoons for eating your treat!

Activity while we are mixing our ice cream Worksheets 55, 56

Activity- Make Ice Cream in a Baggie: Freezing Point Depression and Colligative Properties Explanation Ice has to absorb energy in order to melt, changing the phase of water from a solid to a liquid. When you use ice to cool the ingredients for ice cream, the energy is absorbed from the ingredients and from the outside environment (like your hands, if you are holding the baggie of ice!). When you add salt to the ice, it lowers the freezing point of the ice, so even more energy has to be absorbed from the environment in order for the ice to melt. This makes the ice colder than it was before, which is how your ice cream freezes. Ideally, you would make your ice cream using 'ice cream salt', which is just salt sold as large crystals instead of the small crystals you see in table salt. The larger crystals take more time to dissolve in the water around the ice, which allows for even cooling of the ice cream. You could use other types of salt instead of sodium chloride, but you couldn't substitute sugar for the salt because (a) sugar doesn't dissolve well in cold water and (b) sugar doesn't dissolve into multiple particles, like an ionic material such as salt. Compounds that break into two pieces upon dissolving, like NaCl breaks into Na+ and Cl-, are better at lowering the freezing point than substances that don't separate into particles because the added particles disrupt the ability of the water to form crystalline ice. The more particles there are, the greater the disruption and the greater the impact on particle-dependent properties (colligative properties) like freezing point depresssion, boiling point elevation, and osmotic pressure. The salt causes the ice to absorb more energy from the environment (becoming colder), so although it lowers the point at which water will re-freeze into ice, you can't add salt to very cold ice and expect it to freeze your ice cream or de-ice a snowy sidewalk (water has to be present!). This is why NaCl isn't used to de-ice sidewalks in areas that are very cold.

Physical Changes (cont.) Dissolving, or evenly mixing, is a physical change because the identities of the substances involved do not change. What happens when something dissolves?

Lab- Where did it go? When you dissolve sugar in water, where does the sugar go? One way to find out is to measure the mass of the water and sugar before and after mixing. Procedure 4. Use a balance to find the mass of the flask-balloon assembly. Record the mass in the Data and Observations section below. 5. Lift the end of the balloon, and empty the sugar into the flask. Swirl until the sugar dissolves. Measure and record the mass of the flask-and-balloon assembly again. 1. Read and complete a lab safety form. 2. Add sugar to a small paper cup until the cup is approximately half full. Using a funnel inserted into a balloon, pour the sugar into the balloon. Remove the funnel from the balloon. 3. With the balloon hanging over the side, stretch the neck of the balloon over a flask half full of water.

Conservation of mass Conservation of mass refers to the fact that the total mass before and after a physical change is the same.

Conservation of Mass activity

Conservation of Mass (cont.) What is meant by conservation of mass?

Lesson 3 - Summary During a physical change, matter can change form, shape, size, or state, but the identity of the matter does not change.

Lesson 3 - Summary Matter either changes temperature or changes state when enough thermal energy is added or removed. Mass is conserved during physical changes, which means that mass is the same before and after the changes occur.

Lesson 3 – Review Which term describes what occurs when a solid changes directly to a gas without first becoming a liquid? A. sublimation B. dissolving C. deposition D. condensation

Lesson 3 – Review When thermal energy is added to a solid, what happens to the particles in the solid? A. They move faster. B. They move slower. C. They stop moving. D. Nothing happens.

Lesson 3 – Review Conservation of mass means that the total mass before and after a physical change is which of these? A. different B. greater C. smaller D. the same

Chemical Properties and Changes Lesson 4 Chemical Properties and Changes What is a chemical property? What are some signs of chemical change? Why are chemical equations useful? What are some factors that affect the rate of chemical reactions?

Chemical Properties and Changes Lesson 4 - Vocab Chemical Properties and Changes chemical property chemical change concentration Create a 3-tab vocabulary foldable

Chemical Properties A chemical property is a characteristic of matter that can be observed as it changes to a different type of matter. Chemical properties include ability to burn, acidity, and ability to rust.

Comparing Properties All matter can be described using both physical and chemical properties. The ability of a substance to burn or rot is a chemical property. What are some chemical properties of matter?

Chemical Changes A chemical change is a change in matter in which the substances that make up the matter change into other substances with new physical and chemical properties. The substances that undergo a chemical change no longer have the same properties because they no longer have the same identity.

Signs of Chemical Change Lesson 4-4 Signs of chemical changes include the formation of bubbles or a change in odor, color, or energy. These signs do not always mean a chemical change occurred. The only proof of chemical change is the formation of a new substance. A burnt log or rotted garbage an example of a chemical change

Activity Is it a chemical change? Explain.

Signs of Chemical Change (cont.) What are signs of a chemical change?

Explaining Chemical Reactions Chemical changes often are called chemical reactions. A useful way to understand what happens during a chemical reaction is to write a chemical equation. A chemical equation shows the chemical formula of each substance in the reaction.

Explaining Chemical Reactions (cont.) The formulas to the left of the arrow represent the reactants—the substances present before the reaction takes place. The formulas to the right of the arrow represent the products—the new substances present after the reaction. The arrow indicates that a reaction has taken place.

Explaining Chemical Reactions (cont.) Chemical formulas and other symbols are parts of a chemical equation.

Recreate & Complete the chart on Activity Page Parts of a CHEMICAL Equation Name Meaning Formulas to the left Formulas to the right ---------------------- + (s) State is a solid (l) (g) gas

Explaining Chemical Reactions (cont.) In a chemical equation, the number of atoms of each element before a reaction must equal the number of atoms of each element after the reaction. This is called a balanced chemical equation, and it illustrates the conservation of mass. When balancing an equation, you cannot change the chemical formula of any reactants or products.

Lesson 4-5

increasing the rate of chemical reaction. The Rate of Chemical Reactions Different factors can make particles move faster and collide harder and more frequently, increasing the rate of chemical reaction.

The Rate of Chemical Reactions (cont.) A higher temperature usually increases the rate of reaction because when the temperature is higher, the particles move faster. Concentration is the amount of substance in a certain volume. A reaction occurs faster if the concentration of at least one reactant increases. Surface area also affects reaction rate if at least one reactant is a solid.

The Rate of Chemical Reactions (cont.) List three factors that affect the rate of a chemical reaction.

Chemistry To understand chemistry, you need to understand matter and how the arrangement of atoms results in different types of matter. You also need to be able to distinguish physical properties from chemical properties and describe ways these properties can change.

Lesson 4 - Summary A chemical property is observed only as a material undergoes chemical change and changes identity. Signs of possible chemical change include bubbles, energy change, and change in odor or color. Chemical equations show the reactants and products of a chemical reaction and that mass is conserved.

Lesson 4 – Review Which term refers to a change in matter in which the substances that make up the matter change into other substances with new physical and chemical properties? A. chemical change B. chemical equation C. chemical formula D. physical change

Lesson 4 – REVIEW What must a balanced chemical equation have on both sides of the equation? A. same number of atoms B. same number of compounds C. same number of molecules D. same number of reactants

Which is a chemical change? Lesson 4 – Review Which is a chemical change? A. Paper is shredded. B. Liquid wax turns solid. C. A raw egg is broken. D. A wood log is burning.

The BIG Idea Matter is anything that has mass and takes up space. Its physical properties and its chemical properties can change.

Atoms of different elements have different numbers of protons. Key Concepts 1 Lesson 1: Classifying Matter A substance is a type of matter that always is made of atoms in the same combination. Atoms of different elements have different numbers of protons. The composition of a substance cannot vary. The composition of a mixture can vary. Matter can be classified as either a substance or a mixture.

Physical properties of matter include size, shape, texture, and state. Key Concepts 2 Lesson 2: Physical Properties Physical properties of matter include size, shape, texture, and state. Physical properties such as density, melting point, boiling point, and size can be used to separate mixtures.

A change in energy can change the state of matter. Key Concepts 3 Lesson 3: Physical Changes A change in energy can change the state of matter. When something dissolves, it mixes evenly in a substance. The masses before and after a change in matter are equal.

Key Concepts 4 Lesson 4: Chemical Properties and Changes Chemical properties include ability to burn, acidity and ability to rust. Some signs that might indicate chemical changes are the formation of bubbles and a change in odor, color, or energy. Chemical equations are useful because they show what happens during a chemical reaction. Some factors that affect the rate of chemical reactions are temperature, concentration, and surface area.

Chapter Review – MC1 Which term describes a type of mixture in which the individual substances are not evenly mixed? A. homogeneous mixture B. heterogeneous mixture C. compound D. solution

Chapter Review – MC2 Which is a small particle that is a building block of matter? A. atom B. compound C. element D. substance

Chapter Review – MC3 Which term refers to the amount of matter in an object? A. volume B. solubility C. mass D. density

Chapter Review – MC4 What happens when thermal energy is added to a solid? A. The particles move faster and the temperature increases. B. The particles move slower and the temperature increases. C. The particles move faster and the temperature decreases. D. The particles move slower and the temperature decreases.

Chapter Review – MC5 Which term describes a characteristic of matter that can be observed as it changes to a different type of matter? A. chemical change B. chemical property C. physical change D. physical property

Chapter Review – STP1 Which term refers to a type of mixture in which the individual substances are evenly mixed? A. homogeneous mixture B. heterogeneous mixture C. compound D. matter

Chapter Review – STP2 Which term describes a substance that consists of just one type of atom? A. compound B. element C. matter D. mixture

Chapter Review – STP3 States of matter include solid, liquid, and which of these? A. particles B. mass C. density D. gas

Chapter Review – STP4 Which term refers to the change from a gas directly to a solid? A. condensation B. deposition C. dissolving D. sublimation

Chapter Review – STP5 Which refers to the amount of substance in a certain volume? A. mass B. concentration C. chemical equation D. surface area