58 terms

Chemistry: Atom Stucture


Terms in this set (...)

Basic unit of a chemical element
Atomic Number
Number of protons in the nucleus of an atom
Atomic Mass
Number of protons and neutrons in an atom. Mass of an atom measured in atomic mass units
Positively charged particles
Neutral charged particles
Negatively charged particles
Outermost electron
Quantum Theory
A theory of matter and energy based on the concept of quanta
Dalton Theory
All elements are composed of indivisible atoms. All atoms of a given element are identical. Atoms of different elements are different and have different masses. Compounds are formed by the combination of atoms or different elements
JJ Tompson Theory
Speculated they were randomly positioned within an atom. "Plum pudding model"
Rutherford Theory
Did the Gold Foil experiment explaining; an atom is mostly empty space, contains a small dense POSITIVELY charged nucleus
Bohr Theory
Protons and neutrons were held in the nucleus while electrons orbited around the nucleus
Bohr Model (planetary model)
Protons and electrons are held in the nucleus. Electrons are placed in shells that "orbit" around
Wave Mechanical Model (cloud)
Electrons move closer and farther from the nucleus making a cloud instead of a "fixed pathway". Energy is moves in areas called orbitals.
A mixture in which composition is not uniform. Consists of two or more phases
A mixture in which the composition is uniform throughout, also know as a solution. Consists of one phase
Atomic Mass Unit
A unit of mass used to measure atomic and molecular weights
Made up of one kind of atom and can not be summarized
Made up more than one kind of atom, chemically combined. Can be broken down into the elements that make it up
Excited State
Higher energy level of an atom or particle
Ground State
Lowest energy level of an atom or particle
Two or more forms from an element that have the same number of protons but different number of neutrons. Differ in atomic mass

Mass Number
Amount of protons and neutrons in a nucleus
A region in which an electron of a particular amount of energy is most likely to be located
A physical blend of two or more substances

Ex: Chicken Noodle Soup
Dense central core containing protons and neutrons
Pure Substance
A material that is composed of only one type of particle

Ex: Water Oxygen
Early Studies of an Atom
The Greek's view the nature of matter as being composed of fire, air, water, earth. This lasted until the 1600's. Robert Boyle later found gold and silver identifying them as element.
Used to describe any part of a sample with uniform composition and properties
Passing the mixture through a porous membrane. Powered by gravity. Particles larger than the pore a left behind.
Chromatography/ Electrophoresis
Both used to analyze and separate mixtures.
Capillary Action
Water or liquid travels through a matrix by virtue of the matrix being small and the liquid having adhesive properties (liquid travels up)
Separates liquids based on boiling points. Mixture is heated slowly. Lowest boiling point liquid boils first to a gas. Gas is cooled back to a liquid. Repeated if the mixture contains more than two liquids.
Melting Point
Solid --> Liquid
Boiling Point
Liquid --> Gas
Freezing Point
Solid --> Liquid
Condensation Point
Gas --> Liquid
Indivisible (unbreakable)
Subatomic Particles
a particle smaller than an atom or cluster of particles
Alpha Particle
Positively charged particles that are smaller than an atom
Principle Quantum Number
First number described the major energy level of a neutron
Kinetic Molecular Theory
A model or theory that is used to explain the behavior of gases. Gases contain particles that are constant, random, straight-line motion. Gas particles collide with each other and with the walls of the container. The collisions may result in a transfer of energy among particles but no loss of energy as a result of the collisions. Collisions are perfectly elastic. Gas particles are separated by relatively great distances. Gas particles do not attract each other
Relationship of Pressure and Numbers of Gas Particles
The collisions with the container wall exert a force over the surface area of a wall-the particles exert pressure on the wall. The more gas molecules the more pressure.
Relationships of Pressure and Volume of Gas
Increase in volume causes a decrease in pressure vice versa
Relationship of Temperature and Pressure of a Gas
Increase in temperature causes a increase in pressure vise versa
Relationship of Temperature and Volume of a Gas
Increase in temperature causes a increase in volume
Relationship of Temperature and Velocity
Increase in temperature causes a increase in velocity
A physical substance
How much matter the substance has
How much space it takes up
How much mass is contained in a given unit
Aufrau's Rule
Electrons fill staring at the lowest energy level
Hund's Rule
Electrons do not double up (arrows in boxes/orbitals)
Pauli Exclusion Principle
No more than 2 electrons per orbital or suborbital
Calculating Atomic Mass
(Isotope Mass x Percent) (Isotope Mass x Percent)
Shell/Energy Level
Row in which the element is in

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