chem reviewer

Matter is anything that occupies space and has mass.

atom is the smallest unit of matter that is composed of three sub-atomic particles: the proton, the neutron, and the electron. 

SUBSTANCE is a matter that has a definite or constant composition and distinct properties.

MIXTURE is a combination of two or more substances in which the substances retain their distinct identities.

HOMOGENEOUS MIXTURE The mixing together of these separate pure substances which will be uniform in composition throughout.

HETEROGENEOUS MIXTURE Not uniform in composition throughout.

ELEMENT is a substance that cannot be separated into simpler substances by chemical means.

Dmitri Mendeleev has his own element (Mendelevium, Md), because the most common way of arranging the elements—the periodic table—reflects the system he developed.

NONMETALS This is an orderly arrangement of all the elements based on similarities in their reactivities and properties.

METALLOIDS  Elements that lie between metals and nonmetals in the periodic table.

COMPOUND combination of two or more elements. Reconsidering a sugar solution, water (H2O) is a compound consisting of oxygen and hydrogen atoms.

PHYSICAL PROPERTY A trait of matter that can be observed or measured without changing the chemical composition of the matter.

Color – how the object absorbs and reflects light.

Texture – how the substance looks and feels.

Temperature- A measure of the average kinetic energy (energy of motion) of particles in a substance.

Mass- The amount of matter in an object (in g or kg).

Volume- The amount of space an object occupies (in mL, L, cm3, m3, etc.)

  Density – the ratio of mass to volume; reflects the degree of packing of particles in matter. (D = m/v)

Luster - The way that a substance reflects light (metallic, non-metallic, glassy, pearly, dull).

  Ductility- Ability of a substance to be stretched into a wire.

Malleability - Ability of a substance to be hammered flat and to retain the new shape.

CHEMICAL PROPERTY In the process of testing the chemical property, the substance changes composition if it has that property.

EXTENSIVE PROPERTY Properties that are dependent on the amount of substance present in the material sample. The ratio of mass and volume yields density.

INTENSIVE PROPERTY Properties that are independent of the amount of substance present in a material sample. These properties exit at the molecular level and are inherent to the chemical composition.

·        Melting - changing from solid to liquid.

·        Freezing – changing from a liquid to a solid.

·        Vaporization - changing from liquid to gas.

·        Evaporation – changing from liquid into vapor.

·        Condensation – changing from gas to a liquid.

·        Deposition – changing from gas to a solid.

·        Sublimation – changing from a solid to gas.

ENERGY is known and recognized by its effects. It cannot be seen, touched, smelled, or weighed.

Nonrenewable Energy Sources Comes from sources that will run out or  will not be replenished in our lifetimes—or even in many, many lifetimes.

Kinetic energy the energy produced by a moving object.

Radiant energy, or solar energy comes from the sun and is Earth’s primary energy source. heats the atmosphere and Earth’s surface, stimulates the growth of vegetation through the process known as photosynthesis, and influences global climate patterns.

Thermal energy is the energy associated with the random motion of atoms and molecules. can be calculated from temperature measurements.

Chemical energy stored within the structural units of chemical substances; its quantity is determined by the type and arrangement of constituent atoms.

Potential energy  energy available by virtue of an object’s position.

CHEMICAL REACTIONS form new substances by breaking and making chemical bonds. -       the way the atoms are arranged.

ENERGY CHANGES Almost all chemical reactions absorb or produce (release) energy, generally in the form of heat.

THERMOCHEMISTRY is the study of heat change in chemical reactions.

HEAT CAPACITY A solid material, when heated, experiences an increase in temperature, signifying that some energy has been absorbed.

CALORIMETRY an instrument that measures the gain or loss of heat. -       term used to describe the measurement of heat flow.

ENTHALPY the measurement of energy in a thermodynamic system. The quantity of enthalpy equals to the total content of heat of a system, equivalent to the system's internal energy plus the product of volume and pressure.

EXOTHERMIC REACTION When heat evolves from a system, the process is said to be exothermic and the value of ΔE is less than zero.

ENDOTHERMIC REACTION When heat is absorbed by the system, the process is said to be endothermic, and the value of ΔE is greater than zero.

spontaneous process is capable of proceeding in a given direction without needing to be driven by an outside source of energy.

nonspontaneous reaction is a chemical reaction in which the standard change in free energy is positive and energy is absorbed.

ENTROPY the measure of a system’s thermal energy per unit temperature that is unavailable for doing useful work.

THERMODYNAMICS involves situations in which the temperature or state of a system changes due to energy transfers.

Classical thermodynamics concerns the relationships between bulk properties of matter. Nothing is examined at the atomic or molecular level.

Statistical thermodynamics seeks to explain those bulk properties in terms of constituent atoms. The statistical part treats the aggregation of atoms.

ISOLATED SYSTEM is one that does not interact with its surroundings.

A cyclic process is one that starts and ends in the same state.

adiabatic process is one during which no energy enters or leaves the system by heat.

An isobaric process is one that occurs at a constant pressure.

 isothermal process is one that occurs at a constant temperature.

William Thomson (Lord Kelvin) First to propose the use of an absolute scale of temperature. His work in thermodynamics led to the idea that energy cannot pass spontaneously from a colder object to a hotter object.

WALTHER NERNST -       As per the third law of thermodynamics, the entropy of such a system is exactly zero.

ELECTROCHEMISTRY electricity and chemistry the relationship between a chemical reaction and electricity.

OXIDATION – REDUCTION Electrons move between atoms.

OXIDATION Is the loss of electrons from some chemical species.

REDUCTION Whereas reduction is the gain of electrons.

Galvanic cell AKA Voltaic cell – devices that use chemical reaction to create reaction electricity (oxidation reduction process)

 ELECTROLYSIS Is the process of using electricity to split water into hydrogen and oxygen. This reaction takes place in a unit called an electrolytic cell of electrolyzer.

 COSMIC RAYS are high-energy particles originating from space that travel through the universe, including our solar system, at nearly the speed of light.

SOLAR FLARES Some cosmic rays emanate from the sun, where solar flares can accelerate highly charged cations until they approach the speed of light.

Gamma rays are typically produced during certain nuclear processes and radioactive decay.

Fission is the process of splitting a heavy nucleus into two or more lighter nuclei, along with the release of a large amount of energy

Fusion releases energy when light nuclei come together to form a heavier nucleus. The energy release in fusion is even more substantial than in fission and powers the sun and other stars.

FUELS is any solid, liquid, or gaseous substance that may be combusted (burned) to produce heat or work. Sources of fuel date back to prehistoric times, where solids such as grass and straw were burned for heat.