Science Survey Chemical and Physical Properties of Matter

Matter Matter is anything that has mass and takes up space. Matter is anything that has mass and takes up space. Chemistry is the study of matter and how it changes. Chemistry is the study of matter and how it changes. An element is a substance that cannot be broken down into simpler substances (made of one kind of atom). An element is a substance that cannot be broken down into simpler substances (made of one kind of atom). The smallest particle that has the properties of an element is an atom. The smallest particle that has the properties of an element is an atom.

Matter: Compounds A substance made of atoms of more than one element bound together is a compound. Ex) water, NaCl A substance made of atoms of more than one element bound together is a compound. Ex) water, NaCl Every compound is unique, and is different from the elements it contains. Ex) hydrogen, oxygen, and nitrogen are colorless gases in nature. They combine to form the compound nylon, which is a flexible solid. Every compound is unique, and is different from the elements it contains. Ex) hydrogen, oxygen, and nitrogen are colorless gases in nature. They combine to form the compound nylon, which is a flexible solid.

Matter: Compounds, cont. The smallest unit of a compound that exhibits all of the properties of that substance is a molecule. The smallest unit of a compound that exhibits all of the properties of that substance is a molecule. Chemical formula- the chemical symbols and numbers indicating the atoms contained in a molecule of a substance. Chemical formula- the chemical symbols and numbers indicating the atoms contained in a molecule of a substance. Example: H 2 O is the formula for water. NaCl is the formula for sodium chloride (table salt). Example: H 2 O is the formula for water. NaCl is the formula for sodium chloride (table salt). Formulas show the identity (symbol) and number (represented by subscripts) of atoms in the molecule. Formulas show the identity (symbol) and number (represented by subscripts) of atoms in the molecule.

Pure Substances Pure substance-any matter that has a fixed composition and definite properties, such as a compound. Any sample would be identical to any other. Pure substance-any matter that has a fixed composition and definite properties, such as a compound. Any sample would be identical to any other. Mixture-a combination of more than one pure substance, not chemically combined. Mixture-a combination of more than one pure substance, not chemically combined.

Classifying Matter

Mixtures Heterogeneous mixture- substances that are not uniformly mixed, such as pond water. Heterogeneous mixture- substances that are not uniformly mixed, such as pond water. Homogeneous mixture- substances are evenly distributed throughout the mixture. Includes solutions such as Gatorade, and suspensions such as milk. Homogeneous mixture- substances are evenly distributed throughout the mixture. Includes solutions such as Gatorade, and suspensions such as milk.

Mixtures of Liquids Miscible- two or more liquids that are able to dissolve into each other in various proportions. Example: gasoline is a mixture of liquids that mix well Miscible- two or more liquids that are able to dissolve into each other in various proportions. Example: gasoline is a mixture of liquids that mix well Immiscible- describes two or more liquids that do not mix into each other such as oil and water. Immiscible- describes two or more liquids that do not mix into each other such as oil and water.

Suspensions Suspensions are homogenous mixtures in which the different parts are in different phases. Suspensions are homogenous mixtures in which the different parts are in different phases. Example: Milk is protein and fat dispersed in water. Blood is water containing blood cells, proteins, and other materials. Example: Milk is protein and fat dispersed in water. Blood is water containing blood cells, proteins, and other materials.

States of Matter l solid - definite shape and volume, particles are close together in fixed positions. l liquid - definite volume, indefinite shape. Particles are close together, but can still slide past each other. Liquids take the shape of their container. Viscosity is the resistance of a fluid to flow. For example, syrup is more viscous than water.

States of Matter, cont. gas - neither definite shape nor definite volume; particles are far apart. Gases are free to move in all directions, exerting pressure (force per unit area) on the walls of their containers. plasma- high temperature state of matter where atoms lose their electrons. Plasma is found in fluorescent bulbs, lightning, and stars. **The forces holding solids together are stronger than the forces holding liquids together. The forces holding gas particles together are the weakest.

Phase Model for Water

Kinetic Theory and States of Matter Energy of motion is kinetic energy. The kinetic theory says that all atoms are in motion. Energy of motion is kinetic energy. The kinetic theory says that all atoms are in motion. Increasing temperature causes particles to speed up. Decreasing temperature slows them down. Increasing temperature causes particles to speed up. Decreasing temperature slows them down. At the same temperature, heavier particles move slower than lighter particles. At the same temperature, heavier particles move slower than lighter particles. Matter can change states if the movement of the molecules changes. Matter can change states if the movement of the molecules changes.

Changes of State Energy is the ability to change or move matter. Energy is the ability to change or move matter. Energy is needed for matter to change state, such as from a solid to liquid, or from liquid to gas. Energy is needed for matter to change state, such as from a solid to liquid, or from liquid to gas. Endothermic processes require added energy, while exothermic process release energy to the environment. Endothermic processes require added energy, while exothermic process release energy to the environment.

Changes of state, cont. Evaporation is the change of a substance from a liquid to a gas. Evaporation is the change of a substance from a liquid to a gas. Condensation is the change of a gas to liquid form. Condensation is the change of a gas to liquid form. Sublimation is the change of a solid directly to a gas Sublimation is the change of a solid directly to a gas

Endothermic and Exothermic changes of State

Laws of Conservation Changing the state of matter does not change its composition or mass. Changing the state of matter does not change its composition or mass. Law of Conservation of Mass- Mass cannot be created or destroyed. Law of Conservation of Mass- Mass cannot be created or destroyed. Law of Conservation of Energy- Energy cannot be created or destroyed. Law of Conservation of Energy- Energy cannot be created or destroyed. Mass and energy can change forms. For example, when an ice cube melts, the mass of liquid water is the same as the mass of the ice cube. Mass and energy can change forms. For example, when an ice cube melts, the mass of liquid water is the same as the mass of the ice cube.

Physical properties Physical property- a characteristic of a substance that can be observed or measured without changing the composition of the substance. Physical property- a characteristic of a substance that can be observed or measured without changing the composition of the substance. Examples: shape, color, odor, texture, boiling point, density Examples: shape, color, odor, texture, boiling point, density

Comparison of Chemical and Physical properties

Chemical properties Chemical property- the way a substance reacts with others to form a new substance with different properties. Chemical property- the way a substance reacts with others to form a new substance with different properties. Examples: Gasoline is flammable. Examples: Gasoline is flammable. Sodium reacts easily with other elements, so it is in compounds in nature. Sodium reacts easily with other elements, so it is in compounds in nature.

Physical properties: Definitions Boiling point- temperature at which a liquid becomes a gas below the surface. Water boils at C and freezes at 0 0 C. Boiling point- temperature at which a liquid becomes a gas below the surface. Water boils at C and freezes at 0 0 C. Freezing point- the temperature at which a liquid becomes a solid. Freezing point- the temperature at which a liquid becomes a solid. Melting point- the temperature at which a solid becomes a liquid. Melting point- the temperature at which a solid becomes a liquid.

Density Density- physical property of a substance that describes its mass per unit of volume. Density- physical property of a substance that describes its mass per unit of volume. Density = Mass / Volume D=M/V Density = Mass / Volume D=M/V Units are g/ml of g/cm 3 Units are g/ml of g/cm 3 Why does ice float? It is less dense than water Why does ice float? It is less dense than water Buoyancy- the force with which a more dense fluid pushes a less dense substance upward. Buoyancy- the force with which a more dense fluid pushes a less dense substance upward.

Chemical Changes Chemical changes occur when a substance changes composition by forming one or more new substances. Chemical changes occur when a substance changes composition by forming one or more new substances. Examples: gasoline burns to release carbon dioxide and energy, egg white chemically changes to a solid when heated Examples: gasoline burns to release carbon dioxide and energy, egg white chemically changes to a solid when heated

Physical Changes Physical change- A change in the physical form or properties of a substance that occurs without a change in the identity of the substance. Physical change- A change in the physical form or properties of a substance that occurs without a change in the identity of the substance. Examples: Grinding peanuts into peanut butter, pounding a gold nugget into a ring, shredding paper Examples: Grinding peanuts into peanut butter, pounding a gold nugget into a ring, shredding paper

Physical changes, cont. Dissolving a substance in solution is a physical change, such as dissolving a solid in a liquid or a liquid in a liquid. Dissolving a substance in solution is a physical change, such as dissolving a solid in a liquid or a liquid in a liquid. Changes of state, such as melting, evaporating, boiling, condensing, and freezing are all physical changes. Changes of state, such as melting, evaporating, boiling, condensing, and freezing are all physical changes.