Chemistry+Terms

Chemistry Terms to Know Chapter 1


 * **Hypothesis** : tentative explanation of certain facts that provides a basis for further experimentation
 * **Theory** : explanation of the general principles of certain phenomena
 * **Scientific law** : simple statements of natural phenomena to which no exceptions are known
 * **Matter** : anything that has mass and occupies space
 * **Solid** : has definite shape and volume
 * **Liquid** : has definite volume but not a definite shape
 * **Gas** : indefinite volume and no fixed shape
 * **Homogenous matter** : uniform in appearance and has the same properties throughout
 * **Heterogeneous** : matter consisting of two or more physically distinct phases
 * **Phase** : homogenous part of a system separated from other parts by physical boundaries
 * **Mixture** : material containing two or more substances

Chapter 2


 * **Measurement** : quantitative observation
 * **Mass** : amount of matter in the object
 * **Weight** : measure of the effect of gravity on the object
 * **Volume** : amount of space occupied by matter
 * **Heat** : form of energy associated with the motion of small particles of matter
 * **Temperature** : measure of the intensity of hear, or how hot a system is, regardless of its size
 * **Density** : ratio of the mass of a substance to the volume occupied by that mass
 * **Specific gravity** : ratio of the density of that substance to the density of another substance

Chapter 3


 * **Element** : substance that cannot be broken down by chemical means or simpler substance
 * **Atom** : smallest unit of an element that can enter into a chemical reaction
 * **Group** : columns of elements with similar chemical properties
 * **Noble gases** : all gases and non reactive
 * **Alkali metals** : group 1a
 * **Halogens** : group 7a
 * **Metals** : solid at room temperature; high luster, are good conductors of heat, are malleable and ductile, high melting point, high density
 * **Nonmetals** : not lustrous, low melting points, poor conductors of heat
 * **Metalloid** : have properties that are intermediate between those of metals and those of nonmetals
 * **Diatomic molecules** : contain exactly two atoms (HOFBrINCl)
 * **Compound** : distinct substance that contains two or more elements chemically combined in a definite proportion by mass
 * **Molecule** : smallest uncharged individual unit of a compounds formed by the union of two or more atoms
 * **Ion** : positively or negatively charged atom or group of atoms
 * **Cation** : positively charged ion
 * **Anion** : negatively charged ion

Chapter 4


 * **Physical properties** : inherent characteristics of a substance that can be determined without altering its composition they are associated with its physical existence
 * **Chemical properties** : ability of a substance to form new substances, either by reaction with other substances or by decomposition
 * **Physical change** : changes in physical properties or changes in the state of matter without an accompanying change in composition
 * **Chemical change** : new substances are formed that have different properties and composition from the original material
 * **Law of conservation of mass** : no change is observed in the total mass of the substances involved in a chemical change, basis for the quantitative mass relationship among reactant and products
 * **Energy** : capacity of matter to do work
 * **Potential Energy** : stored energy
 * **Kinetic Energy** : energy that matter possesses due to its motion
 * **Specific Heat** : quality of hear (lost of gained) required to change the temperature 1g of that substance by 1 ° C
 * **Law of conservation of energy** : energy can be neither created nor destroyed, though it can be transformed from one form to another

The Scientists __http://quizlet.com/1584615/chem istry-scientists-flash-cards/__
 * Joseph Priestly**:
 * ** discovered Oxygen
 * **Ernest Rutherford:**
 * established that there is a heavy, dense, positively charged nucleus (protons and neutrons) and most of an atom is empty space
 * the mass of an atom is the combined mass of its protons and neutrons
 * **Wolfgang Pauli:**
 * established the Pauli exclusion principal: only two electrons can occupy the same orbital, and they must have opposite spins
 * **Friedrich Hund**:
 * established Hund's Rule: electrons want to get as far apart as possible (like charges repel), so we put one electron in each orbital within a given sublevel before doubling them up [they fill with one in each orbital before doubling up]
 * **Werner Heisenburg**
 * you can never really know where an electron is in an atom at that exact moment (but you can make a guess)
 * **Neils Bohr**
 * established that electrons exist in specific regions at various distances from the nucleus (energy levels) - he called energy levels orbits (based off of planets)
 * established that an electron cannot exist between energy levels; energy levels are quantized
 * showed that spectral lines result form the radiation of small increments of energy
 * **Amadeo Avogodro**
 * Avogadro's number named after him (6.022x10^23)
 * he investigated quantitative aspects of chemistry
 * **Louis de Broglie**
 * all objects have wave properties:
 * the larger the object, the less noticeable the wave properties
 * the smaller the object, the more noticeable the wave properties (electrons)
 * **Erwin Schrodinger**
 * created a mathematical model based off of Broglie's idea: described electrons as waves
 * **John Dalton**
 * Dalton's Atomic Model:
 * 1) elements are composed of minute particles called atoms
 * 2) atoms of the same element are alike in mass and size
 * 3) atoms of different elements are different in mass and size
 * 4) chemical compounds are formed by the union of two or more atoms of different elements
 * 5) atoms combine to form compounds in simple numerical ratios, such as one to one, two to two, three to three, and so on
 * 6) atoms of two elements may combine in different ratios to form more than one compound
 * Modifications:
 * 1) atoms are composed of subatomic particles (atoms are not the smallest)
 * 2) not all the atoms of a specific element have the same mass
 * 3) atoms can be decomposed (under special circumstances)

(more will be added later)