Terms for chapter 3-4 ☆

plum pudding model

the atomic model developed by J. J. Thomson that views atoms as spheres of positively charged material with embedded electrons

Democritus' thoughts

atoms are indivisible particles
shape and texture varies on the type of matter

aristotle thought

matter is continuous, not made of discrete particles
can be subdivided an unlimited number of times

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

law of electrostatic charges

states that opposite electrical charges attract each other, while like charges repel each other

JJ Thompson thought

tiny, negatively-charged particles, electrons
electrons are part of the atom so atoms are divisible

Rutherford thought

atom's mass and positive charge are packed into a small space called the nucleus

nuclear model

an atom is made up of a tiny, dense, positively charged central nucleus surrounded by negatively charged electrons

Modern Atomic Model

quantum mechanics explore the behavior of matter and energy at the atomic and subatomic levels

Robert Boyle

Began the transition from alchemy to
chemistry

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

Jacob Berzelius

Developed a system of symbols for
naming the elements, using
1–2 letters of each element’s Latin
name

Johann Döbereiner

Created triads and discovered periodicity.

John Newlands

Arranged elements in order by atomic
mass and developed the law of octaves

Dmitri Mendeleev

Arranged elements in columns by
increasing atomic masses

Henry Moseley

Discovered a way to determine the
atomic number

Bohr thought

when at high temperatures each element produces an emission spectrum that produced oly certain wavelengths of light

Bohr model

electrons travel in distinct spherical regions called energy levels at fixed distances from the nucleus

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

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

quantum mechanics

the branch of physics that explores the behavior of matter and energy at the atomic and subatomic level

alpha particle

a helium nucleus that is emitted from a nucleus when a radioactive isotope experiences alpha decay

nucleus

the dense, central portion of an atom

photon

a wave bundle, or particle, of electromagnetic energy

orbital

the region within an atom where an electron will most probably be located; part of the quantum-mechanical model of an atom

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

periodic table

a table that organizes essential information about elements in a manageable format

element

a pure substance that consists of only one kind of atom

triad

a group of three elements with similar characteristics that demonstrates periodicity

periodicity

a repeating pattern in a characteristicla

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

periodic law

states that the properties of elements vary periodically with their atomic numberst

transuranium elements

an element with an atomic number greater than 92, the atomic number of uraniumg

group

a column of the periodic table that includes elements that have similar properties because they have similar electron configurations; also called a family

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

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

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

metalloid

one of a general group of elements with characteristics that are between those of metals and nonmetals; also know as a semiconductor

atomic radius

the distance from the center of an atom's nucleus to its outermost electron

ionization energy

the amount of energy required to remove an electron from an atomf

first ionization energy

the minimum energy required to remove the first electron from its outermost shell

electron affinity

the change in energy when an electron is added to a neutral atom to from an anion (the opposite of ionization energy)

electronegativity

the measure of the attraction between the nucleus and the shared valence electronsd

descriptive chemistry

the study of elements and the compounds they form

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

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

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

inner transition metal

an element from the f block of the periodic table (lanthanoid and actinoid series)

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

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

oxide

a compound that contains oxygen, oxygen combined with one other element

sulfide

a compound that contains sulfur, often combined with another element

halogen

an element of group 17 on the periodic table; highly reactive nonmetal with seven valence electrons

noble gas

an element of group 18 on the periodic table; nonreactive (inert) nonmetallic gas with a full valence shell

continuous theory of matter

the theory that matter can be continuously subdivided without end

atomism

the theory that matter was made of separate, discrete particles that cannot be divided infinitely without losing its properties

atom

the smallest particle that makes up an element and is capable of chemical interactionsl

law of definite proportions

states that every compound is formed of elements combined in specific ratios by mass that are unique for that compound

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

electron

a subatomic particle that has a negative charge and very little massal

alpha particle

a particle consisting of two protons and two neutrons; a positively charged ion

nucleus

the extremely small and dense center of an atom

proton

a subatomic particle located in the nucleus of every atom; has a positive charge

atomic number

the number of protons in the nucleus of an atom

neutron

a subatomic particle located in the nucleus of most atoms; has no charge and a mass of approximately 1 u isotope

mass number

the sum of the protons and neutrons in the nucleus of an atom i

isotope notation

a special notation, used to identify important information about an isotope, consisting of a chemical symbol, atomic number, and mass number

unidentified atomic

the unit used to measure the mass of an atom; also known as a dalton (Da)

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

ion

a charged atom or group of atoms that has gained or lost electrons, producing an unequal number of protons and electrons

anion

a negatively charged ion

cation

a positively charged ion