Term | Definition |
chemistry | The science that deals with the materials of the universe and the changes these materials undergo |
measurement | observations that involve a number and unit |
scientific method | a pattern of investigation procedures |
bias | occurs when a scientist's expectations change how the results are analyzed or how the conclusions are made |
theory | explanation based on repeated observations and investigations |
natural law | a statement about what happens that seems to be true all of the time |
experiment | a method of collecting data to test a hypothesis |
matter | the stuff that the universe is made of |
atom | a fundamental unit of which elements are made |
element | only one type of atom |
allotrope | the same element, but with a different physical form |
compound | atoms of different elements that form a new substance |
molecule | a collection of atoms bonded together that behave as a unit |
physical change | does no effect the composition |
chemical change | when a new substance is formed |
mixture | substances added together without chemical change |
alloy | a solid mixture with metallic properties |
pure substance | either a pure element or compound |
homogeneous mixture | a mixture that is the same throughout |
heterogeneous mixture | a mixture with regions of different properties |
distillation | separation process that depends on the different boiling points of the substances |
filtration | separating by using filter paper |
law of constant composition | a given compound always contains the same proportion of elements |
the Rutherford experiment | discovered that the atom is mostly empty space |
valance electrons | electrons in the outer level or sub level that are involved in reations |
atomic numer | the number of protons |
atomic mass | the number of protons and neutrons |
isotope | the same element but with a different number of nuetrons |
average atomic mass | the average mass of all the isotopes of an element |
half life | the amount of time it takes for half of a sample of an isotope to break down into other elements |
carbon dating | using the decay of C-14 to determine the age of organic substances |
families | columns on the Periodic table |
periods | rows on the Periodic table |
electron dot structure | a shorthand method of showing the number of valance electrons |
ion | an atom that has gained or lost electrons |
oxidation number | the charge of an ion |
chemical bond | the force that holds atoms together in a compound |
ionic bond | where electrons are transferred, creating opposite charges which attract |
chemical formula | indicates the elements in a compound and the ratio of the elements |
binary 1 compound | includes two elements, an A group metal and nonmetal |
binary 2 compound | includes a transition metal and nonmetal |
binary 3 compoud | includes two nonmetals |
polyatomic ion | a group of charged atoms that act as a single ion |
acid | a substance that donates a hydrogen ion |
standard | the exact quantity that people use to compare measurements |
length | straight line distance between two points |
mass | the amount of matter in an object |
volume | amount of space occupied by an object |
density | the mass per unit volume of a material |
temperature | the average kinetic energy of all particles in an object |
scientific notation | the shorthand method of reporting large and small numbers |
accuracy | the degree to which a measurement agrees with the actual value |
precision | the refinement in a measurement |
significant figures | those digits that carry meaning and contribute to precision |
molar mass | the mass of 1 mole of a sbustance |
percent composition (by mass) | the percent of the mass a compound makes up in an element |
empirical formula | the smallest whole number ratio of elements in a compound |
molecular formula | a formula of a compound that indicates the true number of the atoms of each element |
hydrate | a compound with water chemically attached to it |
chemical reaction | a well-defined example of a chemical change |
strong electrolyte | completely splits apart in a solution |
nonelectrolyte | has no ions and doesn't split in a solution |
molecular equation | equation where all species are listed as molecules |
complete ionic equation | equation where all ions are included before and after |
net ionic equation | equation that removes all spectator ions |
synthesis | a reaction where two or more substances combine to form a new, simpler substance |
combustion | a reaction where CO2 and H2O are formed |
decomposition | a reaction where one substance breaks into two or more simpler substances |
single-displacement | a reaction where one element replaces another in a compouund |
acid- base reactions | a reaction where H2O and a salt are formed |
oxidation-reduction | a reaction where electrons are transferred |
oxidized | becomes more positively charged |
reduced | becomes more negatively charged |
salt | an ionic compound whose cation comes from a base, and anion from an acid |
double-displacement | a reaction where a precipitate, water, or gas is formed when two ionic compounds in a solution are combined |
activity series | a list of metals arranged in decreasing ease of oxidation |