Chemistry Mrs. Ramos

Matter and Energy Mass is the amount of matter Matter is anything that has mass and takes up space. Volume is the amount of space, measured in cubic units, that an object or substance occupies. Density is the ratio of mass to volume, or mass divided by volume (D=m/v express in g/cm³)

Extensive properties depend on the amount of matter that is present Extensive properties depend on the amount of matter that is present. Examples are mass, volume, length and total charge. Intensive properties do not depend on the amount of matter present. Examples are density, melting point, boiling point, specific heat.

Physical changes and properties Physical change is a change in a substance that does not involve a change in the identity of the substance. Like the change of water in water vapor. Physical property is a characteristic that can be observed or measured without changing the identity of the substance. (color, odor, density, taste)

State of matter

State of matter

Relationship between energy and state of matter

Relationship between energy and state of matter Energy is absorbed when matter goes from solid liquid gas plasma Energy is released when matter goes from plasma gas liquid solid

Chemical changes and chemical properties A chemical change takes place when one or more substances are combined to form a different one. That is also called a chemical reaction Reactants ----------------- Products substances that substances that are react formed Example: When charcoal is burned the chemical reactions can be described with the following chemical reaction Carbon + Oxygen ------- Carbon dioxide

Chemical changes and chemical properties A chemical change relates to a substance’s ability to undergo changes that transform it into different substances Examples : the ability of iron to rust when combining with the oxygen to form an oxide or the ability metals has to form a salt when combining with a non-metal. In both examples the reactants were transformed into another substances (product)

Classification of matter Mixtures: A blend of two or more kinds of matter, each of which retains its own identity. Example: When you mix milk and cereal in a bowl Mixtures can be classified in homogeneous or heterogeneous. Homogeneous mixtures are uniform in composition and they also can be called solutions. A salt-water solution is an example of homogeneous mixture. (unable to see the salt in the solution) Heterogeneous mixtures are not uniform like oil and vinegar. The more dense liquid will go to the bottom while the less dense stays on top. In an heterogeneous mixture, the difference substances can be seen.

Pure substances are homogeneous and has always a fixed composition and they differ from a mixtures in the following ways: Every sample of a given pure substance has exactly the same characteristic properties Every sample of a given pure substance has exactly the same composition. Examples of pure substances: Water, oxygen, hydrogen, carbon dioxide. Pure substances can be classified in : Compounds are substances composed of atoms of two or more elements chemically united in fixed proportions. Examples : H2O, NaCl, FeCl2 Elements are substances that cannot be separated into simpler substances by chemical means. Examples: O2, Fe, Li, Na.

Methods used to separate matter Chromatography is the separation of a mixture by passing it in solution or suspension or as a vapor (as in gas chromatography) through a medium in which the components move at different rates.

Methods used to separate matter Distillation is the evaporation and subsequent collection of a liquid by condensation as a means of purification: the distillation of water. The extraction of the volatile components of a mixture by the condensation and collection of the vapors that are produced as the mixture is heated: petroleum distillation. What is the property used in the distillation process?

Methods used to separate matter Filtration is the process of separating suspended solid matter from a liquid, by causing the latter to pass through the pores of some substance, called a filter. The liquid which has passed through the filter is called the filtrate. The filter may be paper, cloth, cotton-wool, asbestos, slag- or glass-wool, unglazed earthenware, sand, or other porous material. What is the property used in the filtration process?

How elements are arranged? Elements are organized into groups based on similar chemical properties The organization of elements is The vertical columns of the periodic table are called groups or families The horizontal rows of elements in the periodic table are called periods

Classification of elements Metals are elements that are good conductors of electricity and heat. Most metals are solids at room temperature and also have the property of malleability, that is that they can be hammered or rolled into thin sheets. They also tend to be ductile, which means they can be drawn into fine wire. Metals behave this way because they have a high tensile strength. Most metals have a silvery or grayish white luster with the exception of copper and gold that are reddish and yellow respectively

Classification of elements Non- metal are gases at room temperature with the exception of Bromine that is liquid. The solids nonmetals include carbon, phosphorous, selenium, sulfur, and iodine. These solids tend to be breakable rather than malleable and ductile. They have low conductivity; consequently, they are poor conductors of electricity and heat

Classification of elements Metalloids are elements that have some characteristics of metals and some characteristics of nonmetals. All metalloids are solids at room temperature. They tend to be less malleable than metals but not as brittle as nonmetals. Metalloids are semiconductors of electricity that is why they are used to build computer circuitry, digital watches, televisions, and radios.

Classification of elements Noble Gases are located in the last column of the periodic table. They are gases that have low reactivity which make them different from other groups of families. Neon, Argon, Krypton, and Xenon are all used in lighting. Helium is used in party balloons and weather balloons because it is less dense than air.

State of matter

The Kinetic-Molecular Theory of Matter The kinetic-molecular theory is based on the idea that particles of matter are always in motion

The kinetic-molecular theory of Gases The kinetic-molecular theory of gases is based on the following five assumptions: Gases consist of large numbers of tiny particles that are far apart relative to their size. Collision between gas particles and between particles and container walls are elastic collisions. An elastic collision is one in which there is no net loss of total kinetic energy Gas particles are in continuous, rapid, random motion. They therefore possess kinetic energy, which is energy of motion There are no forces of attraction between gas particles The temperature of a gas depends on the average kinetic energy of the particles of the gas

An ideal gas is a hypothetical gas that perfectly fits all the assumptions of the kinetic-molecular theory. The noble gases as helium (He) and neon (Ne) show essentially ideal gas behavior because their particles have little attraction for each other A real gas is a gas that does not behave completely according to the assumptions of the kinetic-molecular theory. The more polar the molecules of a gas are, the greater the attractive force s between them and the more the gas will deviate from behaving like an ideal gas. NH3 (ammonia) and water vapor are examples of real gases

Comparing solids, liquids, and gases Expansion and Compressibility Fluidity Density Diffusion and Effusion Gases They expand to fill any container. Also can be compressed by applying pressure reducing the volume occupied Yes, they are fluids Low density Due to the rapidly motion of the molecules, they diffuse and effuse quickly Liquids They do not expand because they have a definite shape and they are much less compressible than gases yes, they are fluids More dense than gases, but less dense than solids Diffusion is slower in liquids than in gases Solids They can be classified as incompressible - Slightly denser than liquid and more denser than gases Low rate of diffusion

Vocabulary Words Phase: It is any part of a system that has uniform composition and properties. Equilibrium : It is a dynamic condition in which two opposing changes occur at equal rates in a closed system. Equilibrium vapor pressure: It is the pressure exerted by a vapor in equilibrium with its corresponding liquid at a given temperature Volatile liquids: They are liquids that evaporate readily Boiling point of a liquid: It is the temperature at which the equilibrium vapor pressure of the liquid equals the atmospheric pressure (1 atm=101.3 kPa)

Vocabulary Words Molar enthalpy of vaporization (ΔHv): It is the amount of energy as heat that is needed to vaporize one mole of liquid at the liquid’s boiling point at constant pressure ( Freezing point: It is the temperature at which the solid and liquid are in equilibrium at 1 atm(101.3 kPa). Molar enthalpy of fusion (ΔHf): The amount of energy as heat required to melt one mole of solid at the solid’s melting point at constant pressure (1 atm) Phase diagram: It is a graph of pressure versus temperature that shows the conditions under which the phases of a substance exist.

Vocabulary Words The tripe point of a substance indicates the temperature and pressure conditions at which the solid, liquid, and vapor of a substance can coexist at equilibrium. The critical point of a substance indicates the critical temperature and critical pressure The critical temperature is the temperature above which the substance cannot exist in the liquid state The critical pressure is the lowest pressure at which the substance can exist as a liquid at the critical temperature

Phase Diagram for water