chemistry semester test Flashcards
in an experiment, the standard that is used for comparison
control
in an experiment, the variable whose value depends on the independent variable
dependent variable
a set of controlled observations that test a hypothesis
experiment
in an experiment, the variable that the experimenter plans to change
independent variable
information describes color, odor, shape, or some other physical characteristics
Qualitative data
numerical information, describes how much, how little, how big, how tall, or how fast
Quantitative data
the amount of mass per unit volume; a physical property
density
a systematic approach to problem solving that uses conversation factors to move from one unit to another
dimensional analysis
expresses any number as a number between 1 and 10 (known as a coefficient) multiplied by 10 raised to a power (known as an exponent)
scientific notation
the number of all known digits reported in measurements plus one estimated digit
Significant figure (or digit)
the ability or inability of a substance to combine with or change into one or more new substances
chemical property
a characteristic of matter that can be observed or measured without changing the sample’s composition– for example, density, color, taste, hardness, and melting point
physical property
a process involving one or more substances changing into new substances; also called a chemical reaction
chemical change
states that mass is neither created nor destroyed during a chemical reaction but is conserved
law of conservation of mass
a transition of matter from one state to another
phase change
a type of change that alters the physical properties of a substance but does not change its composition
physical change
a percentage determined by the ratio of the mass of each element to the total mass of the compound
percent by mass
a chart that organizes all known elements into a grid of horizontal rows (periods) and vertical columns (group or families) arranged by increasing atomic number
periodic table
the smallest particle of an element that retains all the properties of that element; is electrically neutral, spherically shaped, and composed electrons, protons, and neutrons
atom
a negatively charged, fast-moving particle with an extremely small mass that is found in all forms of matter and moves through the empty space surrounding an atom’s nucleus
electron
a subatomic particle in an atom’s nucleus that has a positive charge of 1+
proton
a neutral, subatomic particle is an atom’s nucleus that has a mass nearly equal to that of a proton
neutron
The extremely small, positively charged, dense center of an atom that contains positively charged protons and neutral neutrons
nucleus
the weighted average mass of the isotopes of that element
atomic mass
the number of protons in an atom
atomic number
atoms of the same element with different numbers of neutrons
isotope
states that each electron occupies the lowest energy orbital available
aufbau principle
the arrangement of electrons in an atom, which is prescribed by three rules— the Aufbau Principle, the Pauli exclusion principle ,and Hund’s rule
electron configuration
Consists of an element’s symbol, representing the atomic nucleus and inner-level electrons, that is surrounded by sots, representing the atom’s valence electrons
electron-dot structure (lewis structure)
states that single electrons with the same spin must occupy each equal-energy orbital before additional electrons with opposite spins can occupy the same orbitals
Hund’s rule
States that a maximum of two electrons can occupy a single atomic orbital but only if the electrons have opposite spins
pauli exclusion principle
the electrons in an atom’s outermost orbitals; determine the chemical properties if an element
Valence electrons
in the periodic table, the f-block elements from period 7 that follow the element actinium
actinide series
Group 1 elements, except for hydrogen, they are reactive and usually exist as compounds with other elements
alkali metals
group 2 elements in the modern periodic table and are highly reactive
alkaline earth metals
a vertical column of elements in the periodic table arranged in order of increasing atomic number; also called a family
Group
a highly reactive group 17 element
halogens
in the periodic table, the f-block elements from period 6 that follow the element lanthanum
lanthanide series
an element that is solid at room temperature, a good conductor, of heat and electricity, and generally is shiny; most are ductile and malleable
metal
an element that has physical and chemical properties of both metals and nonmetals
metalloid
an extremely unreactive group 18 element
noble gas
elements that are generally gasses or dull, brittle solids that are poor conductors of heat and electricity
nonmetal
a horizontal row of elements in the modern periodic table
period
an element in groups 3-12 that is contained in the d-block of the periodic table, and with some exceptions, is characterized by a filled d orbitals of energy level n-1
transitional metal
an atom or bonded group of atoms with a positive or negative charge
ion
states that atoms lose, gain, or share electrons in order to acquire the stable electron configuration of a noble gas
octet rule
