the atomic model developed by J. J. Thomson that views atoms as spheres of positively charged material with embedded electrons
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Democritus' thoughts
atoms are indivisible particles shape and texture varies on the type of matter
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aristotle thought
matter is continuous, not made of discrete particles can be subdivided an unlimited number of times
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John Dalton thought
elements are made of atoms atoms are indivisible, cannot be destroyed atoms of an element are all alike combine chemically in small whole number ratios
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law of electrostatic charges
states that opposite electrical charges attract each other, while like charges repel each other
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JJ Thompson thought
tiny, negatively-charged particles, electrons electrons are part of the atom so atoms are divisible
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Rutherford thought
atom's mass and positive charge are packed into a small space called the nucleus
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nuclear model
an atom is made up of a tiny, dense, positively charged central nucleus surrounded by negatively charged electrons
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Modern Atomic Model
quantum mechanics explore the behavior of matter and energy at the atomic and subatomic levels
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Robert Boyle
Began the transition from alchemy to chemistry
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Antoine Lavoisier
Made one of the first lists of known elements, which included 33 elements known in his day and explained that fire is not an element
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Jacob Berzelius
Developed a system of symbols for naming the elements, using 1–2 letters of each element’s Latin name
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Johann Döbereiner
Created triads and discovered periodicity.
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John Newlands
Arranged elements in order by atomic mass and developed the law of octaves
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Dmitri Mendeleev
Arranged elements in columns by increasing atomic masses
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Henry Moseley
Discovered a way to determine the atomic number
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Bohr thought
when at high temperatures each element produces an emission spectrum that produced oly certain wavelengths of light
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Bohr model
electrons travel in distinct spherical regions called energy levels at fixed distances from the nucleus
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quantum-mechanical model
the currently accepted atomic model in which electrons are found in orbitals that are positioned around a nucleus that contains protons and (usually) neutrons
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energy level
in the Bohr model of the atom, the regions located at fixed distances from the nucleus of an atom in which electrons are found
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quantum mechanics
the branch of physics that explores the behavior of matter and energy at the atomic and subatomic level
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alpha particle
a helium nucleus that is emitted from a nucleus when a radioactive isotope experiences alpha decay
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nucleus
the dense, central portion of an atom
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photon
a wave bundle, or particle, of electromagnetic energy
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orbital
the region within an atom where an electron will most probably be located; part of the quantum-mechanical model of an atom
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workability
the basis upon which a model is assessed, taking into account how well it explains or describes a set of observations and how well the model makes predictions
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periodic table
a table that organizes essential information about elements in a manageable format
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element
a pure substance that consists of only one kind of atom
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triad
a group of three elements with similar characteristics that demonstrates periodicity
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periodicity
a repeating pattern in a characteristicla
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law of octaves
early form of the periodic law devised by John Newlands as he noticed that every eighth known element had similar properties when ordered by increasing atomic mass
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periodic law
states that the properties of elements vary periodically with their atomic numberst
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transuranium elements
an element with an atomic number greater than 92, the atomic number of uraniumg
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group
a column of the periodic table that includes elements that have similar properties because they have similar electron configurations; also called a family
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period
a row in the periodic table that includes elements that have their valence electrons in the same energy level. The period number represents the valence shell; also known as a series
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metal
one of a general group of elements with similar characteristics, such as being solid at room temperature, lustrous, malleable, ductile, and a good conductor of heat and electricity
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nonmetal
one of a general group of elements with similar characteristics, such as generally being a gas or a soft, crumbly solid at room temperature, and being a poor conductor of heat and electricity
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metalloid
one of a general group of elements with characteristics that are between those of metals and nonmetals; also know as a semiconductor
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atomic radius
the distance from the center of an atom's nucleus to its outermost electron
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ionization energy
the amount of energy required to remove an electron from an atomf
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first ionization energy
the minimum energy required to remove the first electron from its outermost shell
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electron affinity
the change in energy when an electron is added to a neutral atom to from an anion (the opposite of ionization energy)
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electronegativity
the measure of the attraction between the nucleus and the shared valence electronsd
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descriptive chemistry
the study of elements and the compounds they form
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alkali metals
element in group 1 on the periodic table; a soft, highly reactive metal that has one valence electron that it easily loses to form a 1+ cation
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transition metal
an element from the d block of the periodic table (groups 3-12); a metal that typically has one or two valence electrons that it easily loses to form a 1+ or 2+ cation
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alkaline-earth metal
an element of group 2 on the periodic table; a reactive metal, having tow valence electrons that it easily loses to form a 2+ cation
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inner transition metal
an element from the f block of the periodic table (lanthanoid and actinoid series)
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actanoid series
a set of elements typically placed at the bottom of the periodic table that consists of the f-block elements form period 7l
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lanthanoid series
A set of elements typically placed at the bottom of the periodic table that consists of the f-block elements from period 6
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oxide
a compound that contains oxygen, oxygen combined with one other element
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sulfide
a compound that contains sulfur, often combined with another element
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halogen
an element of group 17 on the periodic table; highly reactive nonmetal with seven valence electrons
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noble gas
an element of group 18 on the periodic table; nonreactive (inert) nonmetallic gas with a full valence shell
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continuous theory of matter
the theory that matter can be continuously subdivided without end
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atomism
the theory that matter was made of separate, discrete particles that cannot be divided infinitely without losing its properties
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atom
the smallest particle that makes up an element and is capable of chemical interactionsl
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law of definite proportions
states that every compound is formed of elements combined in specific ratios by mass that are unique for that compound
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law of multiple proportions
states that whenever a fixed amount of one element can combine with different masses of a second element, the ratio of masses can be reduced to small, whole numbers
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electron
a subatomic particle that has a negative charge and very little massal
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alpha particle
a particle consisting of two protons and two neutrons; a positively charged ion
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nucleus
the extremely small and dense center of an atom
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proton
a subatomic particle located in the nucleus of every atom; has a positive charge
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atomic number
the number of protons in the nucleus of an atom
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neutron
a subatomic particle located in the nucleus of most atoms; has no charge and a mass of approximately 1 u isotope
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mass number
the sum of the protons and neutrons in the nucleus of an atom i
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isotope notation
a special notation, used to identify important information about an isotope, consisting of a chemical symbol, atomic number, and mass number
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unidentified atomic
the unit used to measure the mass of an atom; also known as a dalton (Da)
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atomic mass
the weighted average (an average that gives more importance to certain values than to others) of the masses of the element's isotopes
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ion
a charged atom or group of atoms that has gained or lost electrons, producing an unequal number of protons and electrons
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Flashcard (110)